Compilation and evaluation of historical data and samples

Compilation and evaluation of historical data and samples
Compilation and evaluation of historical data and samples
to support assessment of phytoplankton and zooplankton
populations in Great Lakes Areas of Concern
W.J.S. Currie, K.L. Bowen, H.A. Niblock and M.A. Koops.
Great Lakes Laboratory for Fisheries and Aquatic Sciences,
Central and Arctic Region, Fisheries and Oceans Canada,
867 Lakeshore Road, Burlington, ON, L7S 1A1
2015
Canadian Technical Report of
Fisheries and Aquatic Sciences 3150
Canadian Technical Report of Fisheries and Aquatic Sciences
Technical reports contain scientific and technical information that contributes to existing knowledge
but which is not normally appropriate for primary literature. Technical reports are directed primarily
toward a worldwide audience and have an international distribution. No restriction is placed on subject
matter and the series reflects the broad interests and policies of Fisheries and Oceans Canada, namely,
fisheries and aquatic sciences.
Technical reports may be cited as full publications. The correct citation appears above the abstract
of each report. Each report is abstracted in the data base Aquatic Sciences and Fisheries Abstracts.
Technical reports are produced regionally but are numbered nationally. Requests for individual
reports will be filled by the issuing establishment listed on the front cover and title page.
Numbers 1-456 in this series were issued as Technical Reports of the Fisheries Research Board of
Canada. Numbers 457-714 were issued as Department of the Environment, Fisheries and Marine Service,
Research and Development Directorate Technical Reports. Numbers 715-924 were issued as Department
of Fisheries and Environment, Fisheries and Marine Service Technical Reports. The current series name
was changed with report number 925.
Rapport technique canadien des sciences halieutiques et aquatiques
Les rapports techniques contiennent des renseignements scientifiques et techniques qui constituent
une contribution aux connaissances actuelles, mais qui ne sont pas normalement appropriés pour la
publication dans un journal scientifique. Les rapports techniques sont destinés essentiellement à un
public international et ils sont distribués à cet échelon. II n'y a aucune restriction quant au sujet; de fait,
la série reflète la vaste gamme des intérêts et des politiques de Pêches et Océans Canada, c'est-à-dire les
sciences halieutiques et aquatiques.
Les rapports techniques peuvent être cités comme des publications à part entière. Le titre exact
figure au-dessus du résumé de chaque rapport. Les rapports techniques sont résumés dans la base de
données Résumés des sciences aquatiques et halieutiques.
Les rapports techniques sont produits à l'échelon régional, mais numérotés à l'échelon national. Les
demandes de rapports seront satisfaites par l'établissement auteur dont le nom figure sur la couverture et
la page du titre.
Les numéros 1 à 456 de cette série ont été publiés à titre de Rapports techniques de l'Office des
recherches sur les pêcheries du Canada. Les numéros 457 à 714 sont parus à titre de Rapports techniques
de la Direction générale de la recherche et du développement, Service des pêches et de la mer, ministère
de l'Environnement. Les numéros 715 à 924 ont été publiés à titre de Rapports techniques du Service des
pêches et de la mer, ministère des Pêches et de l'Environnement. Le nom actuel de la série a été établi
lors de la parution du numéro 925.
Canadian Technical Report of
Fisheries and Aquatic Sciences 3150
2015
Compilation and evaluation of historical data and samples to support assessment of
phytoplankton and zooplankton populations in Great Lakes Areas of Concern.
By
W.J.S. Currie, K.L. Bowen, H.A. Niblock and M.A. Koops
Great Lakes Laboratory for Fisheries and Aquatic Sciences,
Central and Arctic Region, Fisheries and Oceans Canada,
867 Lakeshore Road, Burlington, ON, L7S 1A1
i
© Her Majesty the Queen in Right of Canada, 2015.
Cat. No. Fs97-6/3150E-PDF ISBN 978-0-660-04038-7 ISSN 1488-5379
Correct citation for this publication:
Currie, W.J.S. Bowen, K.L., Niblock, H.A. and Koops. M.A. 2015. Compilation and
evaluation of historical data and samples to support assessment of
phytoplankton and zooplankton populations in Great Lakes Areas of Concern.
Can. Tech. Rep. Fish. Aquat. Sci. 3150: v + 152p.
ii
Table of Contents
ABSTRACT ................................................................................................................................. v
PHYTOPLANKTON AND ZOOPLANKTON POPULATIONS: AN INTRODUCTION .................. 1
SECTION 1: A SPATIAL SURVEY OF TORONTO REGION AOC............................................. 3
Executive Summary................................................................................................................ 3
Section 1.1: A Planktonic Survey of the Toronto Region AOC Using the Towed SHRIMP
Sensor Array. ......................................................................................................................... 5
Rationale............................................................................................................................. 5
Results ................................................................................................................................ 5
Physical-Chemical Measures .......................................................................................... 5
Zooplankton Particle Counts............................................................................................ 6
Tow-Yos .......................................................................................................................... 8
CSMI Western Basin Transect ........................................................................................ 9
Other Surveys ................................................................................................................11
Summary and Conclusions ................................................................................................11
Section 1.2: Toronto Harbour Zooplankton Sampling ............................................................13
Introduction: .......................................................................................................................13
Methods .............................................................................................................................13
Results and Discussion: .....................................................................................................15
Physical Parameters - August 2010: ...............................................................................15
Physical Parameters - September 2013 .........................................................................15
Zooplankton August 2010 Density, Biomass and Community Composition ....................15
Late August 2012 - Density, Biomass and Community Composition...............................17
2013 Toronto Area Surveys - Density, Biomass and Community Composition ...............17
Seasonal and Temporal Trends .....................................................................................18
Cladoceran Mean Size ...................................................................................................19
Rotifers ...........................................................................................................................20
Summary and Conclusions: ...............................................................................................21
Section 1.3: Toronto Harbour Water Chemistry, Physical Conditions, Phytoplankton and
Microbial Loop .......................................................................................................................22
Background: Toronto and Region AOC ..............................................................................22
Historical study of phytoplankton and microbial loop.......................................................22
MOE dataset ..................................................................................................................24
Current Study: Methods .....................................................................................................24
Results ...............................................................................................................................25
Physical parameters: Thermal structure .........................................................................25
Physical parameters: Light Attenuation ..........................................................................26
Water Chemistry and extracted chlorophyll ....................................................................27
FluoroProbe Chlorophyll and Pigment Groups................................................................27
Biological Parameters: Phytoplankton Biomass and Composition ..................................28
Biological Parameters: Size Fractionated Primary Productivity .......................................29
Biological Parameters: Microbial Loop Biomass .............................................................29
Biological Parameters: Bacterial growth rates.................................................................30
Summary and Conclusions ................................................................................................30
Acknowledgements ...............................................................................................................32
References ............................................................................................................................33
Tables ...................................................................................................................................37
Figures ..................................................................................................................................47
iii
SECTION 2: REPORT ON THE VIABILITY OF USING MOE INDEX PLANKTON SAMPLES TO
EVALUATE BUI 13: DEGRADATION OF PHYTOPLANKTON AND ZOOPLANKTON
POPULATIONS FOR TORONTO REGION AREA OF CONCERN ...........................................85
Background ...........................................................................................................................85
Methods and Results .............................................................................................................86
Zooplankton .......................................................................................................................87
Phytoplankton ....................................................................................................................90
Statistical Analysis .............................................................................................................92
Hamilton Harbour Case Study ...............................................................................................96
Summary ...............................................................................................................................99
References ..........................................................................................................................100
Appendix 1: Zooplankton taxonomist comments regarding sample viability/composition .....101
Appendix 2: Phytoplankton taxonomist comments regarding sample viability. .....................102
SECTION 3: REPORT ON PLANKTON SURVEYS RELATED TO THE THUNDER BAY AOC
...............................................................................................................................................104
Introduction .........................................................................................................................104
Survey Procedures ..............................................................................................................105
1971 and 1973 Great Lakes Biological Laboratory Surveys .............................................105
USGS June Surveys ........................................................................................................106
OMOE Index Survey ........................................................................................................106
OMNR 2005 Embayment Surveys ...................................................................................106
2001 Surveillance Survey ................................................................................................107
2011 CSMI Survey ...........................................................................................................107
Results and Discussion .......................................................................................................107
Physical / Chemical Parameters: Temperature ................................................................107
Secchi Depth ................................................................................................................108
Water Chemistry...........................................................................................................108
Phytoplankton ..................................................................................................................109
Biomass and Community Composition .........................................................................109
Phytoplankton productivity ............................................................................................110
Zooplankton .....................................................................................................................111
Zooplankton Density, Biomass and Community Composition .......................................111
Summary of Existing Zooplankton Data ...............................................................................113
Conclusions .........................................................................................................................114
Acknowledgements .............................................................................................................115
References ..........................................................................................................................116
Tables .................................................................................................................................118
Figures ................................................................................................................................135
PHYTOPLANKTON AND ZOOPLANKTON POPULATIONS: CONCLUSIONS ......................151
iv
ABSTRACT
Currie, W.J.S. Bowen, K.L., Niblock, H.A. and Koops. M.A. 2015. Compilation and evaluation of
historical data and samples to support assessment of phytoplankton and zooplankton
populations in Great Lakes Areas of Concern. Can. Tech. Rep. Fish. Aquat. Sci. 3150: v
+ 152p.
This report collects all available data from past literature and unpublished DFO surveys, in three
sub-reports, on two Areas of Concern (AOC) designated requires further assessment for the
Beneficial Use Impairment (BUI 13): “degradation of phytoplankton and zooplankton
populations”. Toronto Region and Thunder Bay AOC are data-poor, with no active plankton
sampling programs. A single 2013 Toronto survey coincided with a large upwelling, with
plankton densities lower than expected within Toronto Harbour, matching results from past
surveys. MOECC Index archived plankton samples were counted, but were insufficient to
evaluate BUI 13 due to high variability and sparse sampling. A minimum six samples annually
are required to determine species composition. Plankton data are documented for Thunder Bay
and Superior, but no samples were available for impacted areas near the Kaministiquia River
and inner Thunder Bay Harbour.
RÉSUMÉ
Currie, W.J.S. Bowen, K.L., Niblock, H.A. and Koops. M.A. 2015. La compilation et l’évaluation
des données historiques et des échantillons à l’appui de l'évaluation des populations de
phytoplancton et zooplancton dans les secteurs préoccupants des Grands Lacs. Can.
Tech. Rep. Fish. Aquat. Sci. 3150: v + 152p.
Ce rapport compile toutes les données trouvées dans trois sous rapports, compris de la
littérature précédemment publiée, aussi bien que des enquêtes de MPO non publiées, sur le
sujet de deux secteurs préoccupants (SP) qui ont été désignés comme exigeant une évaluation
plus approfondie d’utilisations bénéfiques altérées (UBA 13): "la dégradation des populations de
phytoplancton et de zooplancton". Les SP de la région de Toronto et de Thunder Bay ont une
pauvreté de données, n’ayant aucun programme d'échantillonnage actif. Une seule enquête de
Toronto, en 2013, a coïncidé avec une grande remontée d’eau, durant laquelle les densités de
plancton dans le port de Toronto ont été plus faibles que prévu. Ces résultats étaient
semblables à ceux d'enquêtes passées. Les échantillons de plancton archivés par l'indice de
MEACC ont été comptés. À cause de la haute variabilité et l'échantillonnage peu fréquent, il n'y
avait pas un nombre suffisant d'échantillons pour évaluer UBA 13. Un nombre minimum de six
échantillons, annuellement, est exigé pour déterminer la composition en espèces. Les données
de plancton sont documentées pour Thunder Bay et pour le lac Supérieur, mais aucun
échantillon n'était disponible pour les zones affectées situés près de la rivière Kaministiquia et
le port intérieur de Thunder Bay.
v
PHYTOPLANKTON AND ZOOPLANKTON POPULATIONS: AN INTRODUCTION
Surveys of plankton populations have always been fraught with difficulties due to the inherent
patchiness of plankton in space along with rapid growth rates and ecological dynamics (e.g.
predation) in time (Folt and Burns 1999, Lovejoy et al. 2001, Mackas et al. 1985). This is a
major difference for plankton communities compared to benthos or fish, where organisms are
generally longer-lived and have slower reproductive rates. Wide deviations from randomness
make analysis of plankton data difficult and amplify uncertainties. This underlying variability has,
to some degree, created challenges in many Great Lakes Areas of Concerns (AOC) in
managing the “requires further assessment” (RFA) status of the Beneficial Use Impairment (BUI
#13) Degradation of phytoplankton and zooplankton populations. These RFA sites need to be
categorized as impaired or unimpaired. The current delisting guidelines for this BUI states:
“When phytoplankton and zooplankton community structure does not significantly
diverge from unimpacted control sites of comparable physical and chemical
characteristics. Further, in the absence of community structure data, this use will be
considered restored when phytoplankton and zooplankton bioassays confirm no
significant toxicity in ambient waters” (IJC, 1991).
Unimpacted control sites rarely exist for AOCs since embayments are generally densely settled
and most have similar urban impacts. As a result, an approach that compares the AOC to a
nearby coastal site is often chosen. However, these sites generally have very different
hydrological conditions so this approach often is of little utility because the ecological
communities and the scales of patchiness are different. This is an example of using spatial data
inside and outside the AOC for comparative purposes, which generally requires large numbers
of samples to distinguish them. Another approach is to look at changes over time (temporal
argument) but many AOCs have even less plankton sampling data over time.
While most AOCs lack extensive plankton surveys done over time (the exception is the Bay of
Quinte), most of them have had periodic surveys that take place due to sampling for other
programs, so some information on community structure is generally available. However, many
of these datasets are unpublished, difficult to track down, and in some cases, require analysis of
archived physical samples of plankton. Taxonomic identification of “lower trophic level” plankton,
particularly for phytoplankton, is limited to a relatively small community of individuals, and the
capacity to evaluate the data is in equally short supply. The Great Lakes Laboratory for
Fisheries and Aquatic Sciences (GLLFAS) of Fisheries and Oceans Canada (DFO) has a long
history of expertise in the study of lower food-web dynamics, so has been asked to tackle this
BUI for many locations. This report documents a comprehensive review of the available data
from previous surveys of plankton populations within two historically under-sampled Great
Lakes AOCs: Toronto Region, Lake Ontario and Thunder Bay, Lake Superior. These findings
will be useful to support future analyses to evaluate the status of BUI #13 for these sites.
The first section of this report documents a spatial survey, commissioned by Environment
Canada, of the Toronto Region AOC using DFO’s towed instrument technology (Section 1, “A
Planktonic Survey of the Toronto Region AOC”). This section centers on a single survey of the
entire coastal extent of the Toronto Region AOC from Etobicoke Creek to the Rouge River that
took place over a single week in September 2013 (Sept. 9,11,13), which coincided with a major
coastal upwelling in the Toronto area. Since this study was an opportunity to sample the entire
planktonic ecosystem for the Coordinated Science Monitoring Initiative (CSMI) Lake Ontario
year, zooplankton, phytoplankton, microbial plankton and primary production measures were
also taken, which are included in this section to support future analysis. Past findings from the
1
literature on plankton surveys and a summary of unpublished data in the Toronto region are
also compiled here.
The second section documents an evaluation of the use of archived plankton samples from the
Ontario Ministry of the Environment (now OMOECC) Nearshore Index sampling program to
assess the status of BUI #13 for Toronto AOC (Section 2: “Report on the Viability of Using MOE
Index Plankton Samples to Evaluate BUI 13 for Toronto Harbour AOC”). The Index program
samples nearshore sites, including several AOCs, 3 times per year, every 3 years in the lower
lakes, and every 6 years in the upper lakes, beginning in 1994. Even if the Index samples, in
and of themselves, are insufficient for an evaluation of plankton populations at a single AOC,
they can provide a piece of evidence, which can be used in combination with other data
collected from the site. Based on a comparison to the more intensive sampling in Hamilton
Harbour by DFO, sampling frequency recommendations are made for future plankton sampling
programs to adequately capture community composition.
Compared to the lower lakes, there is meagre published information on phytoplankton and
zooplankton populations in Lake Superior. The third section presents and summarizes the
plankton data that is available to date for the Thunder Bay area (Section 3: “A Report on
Plankton Surveys Relating to the Thunder Bay AOC BUI 13”). All data that could be found for
other, relatively more numerous, coastal, offshore and embayment areas in Lake Superior are
made available for comparative purposes. This includes available published literature, Canadian
government databases and compiled data from several unpublished studies conducted by
federal and provincial agencies in Canada and the United States, including some previously
uncounted archived zooplankton samples which we taxonomically enumerated. Though no data
were found for locations within the directly impacted area of Thunder Bay Harbour, data
contained in this report could be used to evaluate the status of BUI 13 following future surveys
of this AOC.
2
SECTION 1: A SPATIAL SURVEY OF TORONTO REGION AOC
Executive Summary
This report documents the results of a plankton survey of the Toronto Region Area of Concern
(AOC) by Fisheries and Oceans Canada (DFO) that took place on three days over a single
week of September 9-13, 2013 in support of the evaluation of the degradation of phytoplankton
and zooplankton communities Biological Use Impairment (BUI #13). The survey encompassed
the entire spatial extent of the AOC from Etobicoke Creek to Rouge River with more spatial
detail in and around Toronto Harbour. Though the primary intent of this study was to generate
spatial information on the plankton distributions around Toronto Harbour using a towed device,
an effort was extended to sample the entire planktonic ecosystem. The principal investigation
involved a survey using towed sensors, which included optical measures of chlorophyll-a
(phytoplankton), turbidity (suspended solids) and physical water characteristics such as
temperature, pH, conductivity and oxygen (Section 1: “A Planktonic Survey of the Toronto
Region AOC Using the Towed SHRIMP Sensor Array”). The towed array included a Laser
Optical Plankton Counter which counted and sized particles (zooplankton) down to ~80-100 µm
in size. To obtain taxonomy and not just size from the LOPC, depth-stratified zooplankton net
samples were collected at a number of stations inside and outside the harbour (Section 2,
“Toronto Harbour Zooplankton Sampling”). Since this study coincided with the 2013
Coordinated Science Monitoring Initiative (CSMI) Lake Ontario year, phytoplankton, microbial
plankton and primary production measures were also taken at matching stations which are
included in this report (Section 3, “Water chemistry, physical conditions, phytoplankton and
microbial loop”).
During the first week of September 2013, the entire Toronto coastline experienced a strong,
widespread upwelling of cold hypolimnetic water as shown by the survey results in the
distribution of physical characteristics (temperature), chlorophyll, and zooplankton densities. In
particular, the area in Ashbridges Bay and along the scarp, where the main Toronto sewage
treatment outflow is located, was highly affected by the upwelling. Elevated values of SRP and
DOC are likely sourced from the outfall. The low zooplankton densities here are certainly related
to the upwelling, so this confounds an examination of the effect of the sewage treatment outfall
on plankton community structure.
Sampling in 2013 and in recent years suggests that Humber Bay experiences deep mixing and
weak stratification, likely due to its orientation to the northwest, which faces into the dominant
prevailing wind direction. Upwelling forces combined with the internal seiche of the lake is likely
to create very specific physical mixing conditions in Humber Bay that are unlikely to be found in
any other location within Lake Ontario, so comparisons to other embayments is difficult. Since
the dominant circulation within Toronto Harbour is from Humber Bay through the western gap
any assessment of the pelagic ecosystem should include stations within Humber Bay.
During the previous limited sampling of the Toronto Harbour area, eutrophic conditions were
routinely found, but during the upwelling low phytoplankton biomass was found at all area
stations, though highest and with lowest diversity in the inner harbour. Primary production was
low within Toronto Harbour, being only slightly elevated from stations outside, the one exception
at the Don River mouth where primary production values were >3 times larger. Stations in and
around Toronto had a dominance of more tolerant, flagellated forms of phytoplankton and
green-algae were a significant portion at inner harbour stations. Bacterial production was
elevated in nearshore stations in Humber Bay and at the Western Gap of Toronto Harbour. LO8
(Humber Bay), which was sampled seasonally for the CSMI, had the highest primary production
and bacterial production values of the season in the Sept survey during the upwelling.
3
Zooplankton populations have not been well studied around Toronto Harbour, but the few
studies available from the coastal region around Toronto suggest that there is both annual and
seasonal variability that include some trends in community composition over time. The existing
historical data and results from this study suggest that Humber Bay and the inner harbour of
Toronto, unlike other embayments in Lake Ontario, have much lower zooplankton densities than
the surrounding region.
Inner Toronto Harbour exhibited very different conditions than the surrounding habitat in
physical water characteristics, with elevated values for temperature, turbidity, nutrients and
chlorophyll. In spite of this situation, which should promote a more eutrophic state and ideal
growth conditions, there were exceedingly low zooplankton counts in Toronto Harbour
compared to the surrounding Lake Ontario coast and other embayments of Lake Ontario. In
particular, there were very few large-sized zooplankton. Embayments within Lake Ontario
typically have much higher zooplankton densities than found in coastal habitats. This is likely
not related to the upwelling since the inner harbour shows higher temperatures than found
outside of the upwelling in the lake, though cold hypolimnetic water from the lake did intrude on
the western side of the harbour, and the few historical surveys support this pattern. Given the
flushing rate of Toronto Harbour near 10 days, at in-situ temperatures, cladoceran zooplankton
should be able to reproduce several generations before being flushed into the Outer Harbour,
and should be able to retain their position against this flushing through vertical migration and
active swimming. This is supported by the high relative percentage of rotifers within the total
zooplankton density. This suggests a possibility that the inner harbour environment is not a
suitable habitat for zooplankton population growth. A more detailed examination of fish
communities should be undertaken to determine any interacting effect of predation on plankton
populations. Further study should involve seasonal sampling of zooplankton to determine
population structure over the spring-fall period and perhaps population growth studies and/or
toxicity studies using incubations.
A single sampling event in 2013 is insufficient to understand the current status of phytoplankton
or zooplankton dynamics, so it is recommended that at least one full sampling season (early
spring to late fall) be undertaken to determine seasonality and the effects of other environmental
factors such as upwelling on plankton viability and community composition.
4
Section 1.1:
A Planktonic Survey of the Toronto Region AOC Using the Towed SHRIMP Sensor Array.
W.J.S. Currie
Rationale
This section documents the results of a towed sensor survey of a planktonic ecosystem for the
entire coastal extent of the Toronto Region AOC from Etobicoke Creek to Rouge River (Fig. 1.1)
that took place over a single week in September 2013 (Sept. 9,11,13). The use of towed
instruments has the advantage of allowing a large spatial area to be surveyed in a short period
of time and determine the spatial variability of measures. The primary instrument of this survey
was the Spatially Hi-Resolution Intensive Mapping of Plankton (SHRIMP) towed array. This form
of optical particle counter has been used in freshwater and estuarine systems for some years
(Blukacz et al. 2009, Currie and Roff 2006, Finlay et al. 2007, Sprules et al. 1998, Vanderploeg
and Roman 2006, Yurista et al. 2012). The sensor package is comprised of a Hi-Res Laser
Optical Plankton Counter (HRLOPC), Conductivity-Temperature-Depth (CTD) probe with
chlorophyll and turbidity optical sensors, and a YSI EXO sonde that has sensors for
temperature, conductivity, pH, dissolved oxygen, total algae (chlorophyll-a and phycocyanin
fluorometers), CDOM and turbidity (Fig. 1.2). A SeaSciences Acrobat towbody is used to
actively control the depth with a resulting tow weight of 40 kg. This instrument package is similar
to the LOPC transects of the 20m isobath of Lake Ontario by Yurista et al. (2012) with the
exception that our HRLOPC is capable of sizing much smaller particle sizes. The tow-path of
the instrument can be seen in the dotted line in Fig. 1.1. This is a daytime epilimnetic tow at a
constant depth of 2.5-3.5 m. The nearshore tow along the coast from Etobicoke to Pickering
followed the 7-10 m isobath. Interpolation was done between the tow tracks using the griddata –
nearest neighbour function and the resulting surface smoothed over three neighbouring points
with smooth2a within MatLab ver.2014a. All graphing was done using MatLab. Dashed lines
indicate areas offshore where the instrument undulates as a “tow-yo” from the surface to ~ 2530m depth (or 2-3m above bottom). The stations listed in Fig. 1.1 indicate sites where vertical
profiles were done from 1 m above bottom to surface using the same instrument which provides
a measure of the planktonic structure in the water column. The LOPC will count and size
particles between ~80 µm – 3 cm of equivalent spherical diameter (Herman et al. 2004) which
encompasses the majority of macrozooplankton, though some very small zooplankton may not
be counted effectively (e.g. small juvenile stages, rotifers and ciliates). Since the LOPC has
limited ability to discriminate taxonomic information, limited number zooplankton net tows at
fixed stations were used to confirm plankton community composition (see Section 1.2).
Results
Physical-Chemical Measures
The mid epilimnetic 3m tow interpolated maps for the entire transect (3 days combined) are
shown in Figs 1.3-4. Winds were variable on these days being mild on the first day (E 5-10
knots), elevated on the second day (SW 10 knots), but was inside Toronto Harbour so
conditions were quite calm until a thunderstorm ended sampling, and on the final day winds
were much increased (N-NW 10 knots gusting 15-20 knots). The physical-chemical maps
indicate a clear strong upwelling around Toronto Harbour as seen in the lower temperature
(~8°C), conductivity (~30 µScm-1) and elevated pH (~1 pH). Temperature is highest offshore
(16°C) and in the inner harbour (17 °C). The upwelling was driven by persistent winds from the
west from September 2-6, 2013 (Fig. 1.4). This drove surface water offshore and upwelled cold
hypolimnetic water along the Toronto scarp which can be seen clearly in the sea-surface
5
temperature satellite image for September 11 (Fig. 1.5). The upwelling zone extended into the
nearshore region of Humber Bay as seen in the temperature distribution on the magnified maps
of Toronto west region (Fig. 1.6). The upwelled water also enters partially into the western gap
of Toronto Harbour since the Harbour is much warmer to the east than the west. This intrusion
is primarily though the hypolimnion as the hypolimnetic water in the Harbour is similar in
temperature to that of nearshore Humber Bay. Since the circulation of Toronto Harbour is westeast, the epilimnetic temperature of Outer Harbour is still much warmer than that surrounding
Toronto (~5°C) with some intrusion along the Leslie Spit. Though upwelling events are common
around Toronto in late August and September, this is an intensive upwelling event which is likely
to influence the distribution of zooplankton and phytoplankton.
The algal and turbidity signals are considerably reduced in the zone of upwelling (Fig 1.3, 1.6).
The chlorophyll-a values are near 3 µgL-1 in the upwelling zone but are 7-8 µgL-1 offshore and
highest (15 µgL-1) within the Harbour around the Don River plume and along the eastern
Harbourfront. The phycocyanin results (the dominant pigment of blue-green algae) mirror this to
some extent but are generally low offshore and are high only around the Don River and eastern
Harbourfront. The distribution of phytoplankton will be addressed in more detail in Section 1.3.
Turbidity is elevated throughout Toronto Harbour extending into the Outer Harbour with
additional small peaks near the Humber River plume. The sensor was calibrated for a widerange of turbidity so even small values (<1 NTU) amount to a very different clarity value (see
Section 1.3, Table 3.1). The Don River plume was visibly brown coloured during the survey but
the area around the entire Harbourfront also was visibly murky which matches the patterns seen
by the towed sensors. Turbidity was also considerably elevated to the east of Toronto, steadily
increasing towards Pickering. This could be due to the Rouge River, but also might be due to
suspended particulates associated with surface transport out from the upwelling, cells within the
water column or calcium precipitates which occur during whiting events (such an event was
observed lakewide in August 2013). The very large spike of specific conductivity (>100 µScm-1
than the surrounding lake water) along the eastern shore of the inner harbour occur immediately
adjacent to the Lafarge wharf and is likely due to increased dissolved ions (calcium,
magnesium, carbonate) associated with offloading and storage at this location.
Zooplankton Particle Counts
The corresponding mid-epilimnetic tow interpolation maps of particle distribution from the Laser
Optical Plankton Counter (LOPC) are showing in Figs. 1.7-8. Most zooplankton are roughly
elliptical in shape so sizes from the LOPC output are standardized to units of Equivalent
Spherical Diameter based on the shading silhouette of the particle (Herman et al. 2004).
Taxonomic groups of zooplankton cannot be cleanly separated simply on the basis of size, but
harmonized size-categories have been used for Hamilton Harbour and the Lake Ontario
Western Basin which are dominated by known groups (Table 1.1). These species are measured
for size during taxonomy (see Section 1.2) but since these measurements are standardized for
length-weight calculations, they must be transformed by empirically based-functions of body
shape and transparency to calculate an ESD for comparison to LOPC data (see (Liebig and
Vanderploeg 2008, Watkins et al. 2011)). There were no clear discontinuities in the normalized
size-spectrum (Herman and Harvey 2006) suggestive of dominant species in the data which
would be indicated by peaks in the log-ESD histogram (see inset Fig. 1.2) so the size categories
in Table 1.1 are appropriate.
The broad-scale distribution (Fig. 1.7) shows total particle counts are highest in the Outer
Harbour of Toronto, but looking at the sizes in more detail, are exclusively dominated by the
smallest size categories of 75-150 µm and 151-300 µm. This is likely composed of dreissenid
veligers, juvenile stages of crustacean zooplankton, rotifers and Bosmina. Total counts are
6
lowest in the zone of the upwelling directly east of Toronto Harbour (near zero). Humber Bay
and to the east of Toronto Harbour also have localized patches of high counts within the 151300 µm sizes (likely dominated by Bosmina or Eubosmina but see Section 1.2). Counts of sizes
above 300 µm are almost entirely absent from within Toronto Harbour and Outer Harbour (a
single particle is encountered for every 2-3 L sampled). The larger zooplankton size categories
of 301-405 µm are elevated near the outlet of Etobicoke Creek to the west and in patches of
high densities in the nearshore from Scarborough to near the Rouge River, though the region
closest to the Rouge River had very low counts approaching the values in the upwelling. The
largest sizes (406-600 µm and 600+ µm) are found occasionally in small patches but in a high
density swath in the nearshore from Ashbridges Bay to the Scarborough Bluffs east of Toronto.
This might be due to a concentrating effect of the upwelling driving surface water from around
the Toronto Scarp to the east along the shoreline. The temperature of this coastal water was in
the 12-13°C range, so cooler-water metalimnetic species such as Limnocalanus and Diacyclops
thomasi might be closer to the surface than they would be normally.
In the higher resolution maps of the Toronto Harbour vicinity (Fig. 1.8), the peaks in total counts
dominated by the smallest particles can be seen in localized patches in the Outer Harbour and
along the eastern coast of the Harbour especially in the Don River plume. Generally sizes >300
µm are highest outside of the harbour in Humber Bay away from shore in the area less affected
by the upwelling. An isolated patch of the 301-600 µm sizes can be seen in the upper Outer
Harbour area but this region nearer the marina could not be fully surveyed due to the extremely
high boat and parasailing activity in the area. A localized patch immediately to the western edge
of the Don River plume along the “Sugar Beach” harbour-front (in the area of the L12 station)
had reasonably high counts of almost all of the size ranges including the largest size category.
The vertical profiles done at the inner and outer harbour stations (Fig. 1.1) from Sept. 11, 2013
can be seen in Fig. 1.9. At the eastern harbour stations (e.g. L12, IH13) the temperature profile
(in red) shows the epilimnetic water is warmer (and the mixed depth is deeper (~4m) than found
at the far western stations (ST1, IH1). The central harbour stations are intermediate in
temperature though they have very different mixed depths to each other: 5 m at MOE1364, the
geographic center used by OMOECC and only 2.5m at TH1364 used by the City of Toronto
which corresponds to the deep hole. The hypolimnetic temperatures of all of the stations are
near 9°C except the shallow L12 station near the Don River. The outer harbour stations (TH1
and OH1) are more similar to the far west inner harbour stations for stratification (shallow mixed
depth) and temperature. The chlorophyll-a profile (in bold dark-green) is generally related to the
depth of stratification with the peak (if one occurs) at the density interface associated with the
lower epilimnion and metalimnion (thermocline). Values of chlorophyll-a ranged from a low of
around 2 at the western stations (ST1) to a high of around 9 near the Don River (L12) station.
The total zooplankton density (in blue) and the individual size-categories indicate that the
eastern stations and the central station (L12, IH13 and MOE1364) have the highest densities in
the meta and hypolimnion. The western stations (ST1 and TH1364) have the highest
zooplankton densities in the shallow epilimnion or no peak at all (IH1). The outer harbour
stations (TH1, OH1) are again similar to the western harbour stations with shallow epilimnetic
peaks in particle densities. The largest particle sizes >300 µm (in yellow, pink or black) are
generally at or near zero but can be seen at a few stations (ST1, IH13, TH1364 and TH1) at the
total zooplankton density peak depth, albeit in a more narrow depth band. It is worth noting that
there was a considerable difference between the central stations (TH1364 and MOE1364) in
terms of stratification, location of chlorophyll-a peak and distribution of particle sizes.
The vertical profiles done at the stations west of Toronto Harbour (3508, LO8) on Sept. 9, 2013
and to the east in Ashbridges Bay (AB2, AB1, 1325, AB3) and off Pickering (708, 1330) (see
7
Fig. 1.1) on Sept. 13, 2013 can be seen in Fig. 1.10. Both of the western stations are very
shallow nearshore stations that show a fairly deep mixed depth of 3 - 4.5 m. The 3508
(Etobicoke) station had a cool epilimnion of 12°C and a hypolimnion of 8°C indicating an
influence of the upwelling. This station had a very modest metalimnetic peak in chlorophyll-a but
a strong peak in total zooplankton density dominated by small particle sizes. The Humber Bay
(HB3/LO8) location is near the input of the Humber River but had a similar epilimnetic
temperature to Etobicoke though little hypolimnion. Unlike many locations the chlorophyll-a max
extended from the surface down to 4m and peak zooplankton particle counts were very close to
the surface.
The Ashbridges stations (shallow to deep AB2, AB1, 1325, AB3) indicated that the two
nearshore stations were highly influenced by the upwelling with cold surface water extending
down for most of the water column. The shallowest station AB1 had a slight deep peak in
chlorophyll-a but extraordinarily low counts of zooplankton. Subsequent net hauls found mostly
very small nauplii and veligers (see Section 1.2, Fig. 2.5). The slightly deeper 1325 station had
more of the water column at a higher chlorophyll-a level but zooplankton counts were also
extremely low with a peak only near the bottom. It should be noted however that at 1325 there
was a relatively high percentage of larger zooplankton particles throughout the water column
suggesting this might be near the edge of the upwelling front. The offshore station AB3 has a
more typical temperature profile, and the surface waters are slightly warmer with the intrusion of
upwelled water seen from 5m down to ~15m. Since there are multiple density interfaces peaks
in chlorophyll-a are found at 5-7m and again around 30m with corresponding increases in
zooplankton particle counts at these depth as well. The larger particles >300 µm are found only
in the top 8m which is the zone above the upwelling intrusion.
The Pickering stations (708 and 1330) do not include a very nearshore station since this was
near the power plant exclusion zone. The water temperature was only slightly elevated (14°C) at
station 708 indicating the previous effect of the widespread coastal upwelling and was only
slightly stratified. The profile at this station is very similar to that found at 1325. The offshore
station at Pickering had little indication of any effect of upwelling, with a warm mixed depth down
to 7m of 16°C, a very wide metalimnion down to 28m and a hypolimnetic temperature of 4-5°C.
The offshore site had a very wide deep chlorophyll-a maximum down to the bottom of the
metalimnion but a local peak at 9m was also associated with a very small peak in zooplankton
densities, including the large fraction >300 µm at the thermocline. A wider band of increased
zooplankton particle densities was also found between 14-22m.
Tow-Yos
The tow-yo transects of the top 25-30 m of the water column are shown in Figs. 1.11-13. Winds
ranged from 5-15 knots, from the E the first day and then W, which built up during the week and
were quite gusty on the final day of sampling (Fig 1.4). The nearshore to offshore transect from
the first day of sampling (Sept. 9) crossing the scarp from AB2 to TH4 (see dashed line Fig. 1.1)
clearly illustrates that the start of the transect is within the upwelling, with most of the water
column near 6°C and a much lower conductivity value matching that of the hypolimnion (Fig.
1.11). The chlorophyll-a value is very low near the start of the transect, though turbidity is
slightly elevated (but still a very low value) suggesting a source of turbidity that is not related to
the upwelling. The zooplankton particle counts are also extremely low in this location for all size
categories. As the transect progresses offshore surface temperature and specific conductivity
increases and a deep chlorophyll maximum (~10m) begins to appear and strengthens toward
the end of the transect. By the end of the transect just offshore of the Outer Harbour the effect
of the upwelling is much reduced, with surface temperatures of 16°C and specific conductivity
50 µScm-1 units higher than the start. The turbidity initially decreases as the transect moves
8
from the nearshore and increases offshore in the surface waters. This may be due to carbonate
precipitate associated with the widespread lake whiting event which took place in late August.
All zooplankton particle size category counts increase along the transect offshore with initially
large particles (406-600 µm) at depth (~20m), which are likely Daphnia sp. or large calanoid
copepods, with smaller size categories increasing in the hypolimnion (below 10m) further along
the transect likely dominated by nauplii and veligers and the larger zooplankton found higher in
the water column near 10m depth (see Section 1.2 for more details).
The second tow-yo transect (Fig. 1.12) on Sept. 9 was from offshore to inshore near Port Credit
and then toward the middle of Humber Bay (LO9 – 1325 – TH4) (dashed line Fig. 1.1). The
temperature stratification is strong and consistent over the transect, and along with conductivity
values this indicates the surface of this section was not highly influenced by the upwelling, but
the very cold hypolimnion (~5°C) at only 15m indicates that deep hypolimnetic water has been
transported from offshore. The chlorophyll-a data indicates much higher values in the epi and
metalimnion which increases in the nearshore but becomes lower moving toward the entry to
Outer Harbour. This last section also indicates elevated turbidity around the middle of Humber
Bay. The zooplankton size data indicates that the deeper sections of the transect have elevated
small size categories (75-300 µm) in the hypolimnion while the larger fraction (>300 µm) are
found in thin layers in the metalimnion or epilimnion. The highest values of the large fraction
(406-600 µm) are found in the nearshore off Port Credit (middle of transect) as shown by two
strong bands of counts around 15m and 5m. This pattern continues in a weaker fashion out to
the middle of Humber Bay suggesting these may be different groups of zooplankton with
differing temperature preferences (e.g. Daphnia and copepods).
The final tow-yo transect for the top 30m of the water column was on Sept. 13 moving west from
offshore Pickering to Ashbridges Bay (1330-1326) along the 60m isobath (Fig. 1.13). Winds
were much increased on this day blowing 10 knots from the N-NW and gusting 15-20 knots.
Temperature stratification was very consistent with warm epilimnetic water (15°C) with slightly
reduced temperature towards Ashbridges Bay, a wide metalimnion and hypolimnion around
25m depth. The chlorophyll-a peak was in the epilimnion and increased towards Ashbridges
Bay. A deep finger of chlorophyll-a that extends down to 20 m can be seen about ¾ along the
transect which is likely driven by a hypolimnetic intrusion creating a downwelling near the edge
of the upwelling front. This idea is reinforced by the very low temperature and turbidity
underneath the intruded water mass. A similar pattern can be seen in the turbidity signal, though
turbidity is overall much higher around Pickering. The patterns of the large zooplankton particles
(406-600 µm) also follow that of the chlorophyll-a signal (concentrated in the epilimnion) and
also shows the downwelling region. The additional layer at 20-30m is matched by the
distribution of smaller particle sizes (<300 µm) which are highly concentrated at this depth for
much of the transect. Again, this is likely due to zooplankton with different temperature
preferences.
CSMI Western Basin Transect
Since this study took place over a very short period of time (several days), to capture some of
the seasonality, some data has been included here from DFO’s Western Basin Transect
associated with the Coordinate Science and Monitoring Initiative on Lake Ontario in 2013 (Fig.
1.14). The transect started off Port Dalhousie and continued across Lake Ontario to Humber
Bay (L08) including the offshore Humber Bay station at 60m (LO9). Transects were carried out
on June 12 (late spring), Aug. 24 (summer) and Nov. 3 (late fall – post stratification). The
northern section of the 30m tow-yo nearest Toronto is shown in Figs. 1.15-16 with the section
between LO9-LO8 indicated by a black bar. Humber Bay was consistently deeply mixed
throughout the year, cooler than offshore water and generally did not exhibit a deep chlorophyll
9
maximum that was persistent offshore from June-Oct (Fig. 1.15). This suggests that the water
column in Humber Bay is being continually disturbed by lake mixing processes likely due to its
orientation facing to the NW. This is in the direction of the dominant westerly prevailing wind
which is likely to promote upwelling. This zone seems to extend out past LO9 into 70-80m of
water depth. The zooplankton particle densities (Fig. 1.16) reinforce the idea that Humber Bay
has a distinct hydrodynamic regime from the offshore of Lake Ontario. In June, the 300-600 µm
(and 600+) sized fraction occur in a thin layer from 5-10m associated with ~12°C water. These
are likely large adult copepods. The smallest sizes are found more offshore in the epilimnion.
During August the very deep mixing with a very wide metalimnion can be seen in the
temperature and conductivity plots (Fig. 1.15). Only the smallest sizes of zooplankton particles
(<300 µm) were found in Humber Bay during summer, highly concentrated into the epilimnion at
temperatures ~ 17°C though they also were found at lower densities deeper in the water
column. These are likely dominated by deissenid veligers, nauplii, small Bosminids and
copepodids (See Section 1.2, Fig. 2.5). The post-stratification November transect indicated the
system was fully mixed (Fig. 1.15) and that there was extremely low densities of any size
category of zooplankton particles with Humber Bay the same as the offshore.
For the CSMI program, vertical profiles were taken during the day and night during June and
August and during the day in September and November at LO8 and LO9 (Figs. 1.17-18). The
60m LO9 station temperature profiles indicate the complex mixing and instability at this station
throughout the year. In June, the chlorophyll-a distribution has no clear single maximum but is
rather distributed down to the top of the hypolimnion at 50m. There is also no obvious peak in
total zooplankton counts in the water column, but when the larger particle sizes are examined, it
is clear that they account for a very large percentage of the total counts in the epilimnion around
8m depth. Specifically, counts in the 406-600 µm size category is larger than the 151-300 µm
counts indicating relatively high densities of large zooplankton of this category certainly
dominated by large adult copepods and Daphnia. During the night, these large zooplankton
disperse slightly to 5-15m but remain at high densities over this depth range. During August, the
chlorophyll-a signal is consistent down to about 30m, again with no strong peak. The total
zooplankton counts indicate a number of peaks (5, 8, 27m) dominated by the smallest sizes
<300 µm. There are increased peaks and coalesced peaks during the night of these small
particles which are likely nauplii and veligers. The 300-405 µm fraction is distributed fairly evenly
from the surface down to 32m during the day and the surface down to 25m at night. This
fraction is likely Bosmina sp (Section 1.2, Fig. 2.5). During the Toronto survey in September,
the stratification was more stable with a much narrower metalimnion. This was driven in part by
a larger proportion of the column being hypolimnetic water that was moved up (to ~15m) as a
result of the large scale upwelling. The chlorophyll-a signal had little vertical pattern other than
being slightly elevated in the epi and metalimnion. The total zooplankton counts were highest in
the hypolimnion with several strong peaks associated with the <300 µm size fraction. The 300405 µm size fraction was distributed fairly evenly down to 45m but the 406-600 µm category,
likely Daphnia sp. and Diacyclops thomasi, was concentrated in the top 10m, though at low
densities. During the isothermal November transect, the profile exhibited very low values and
little vertical patterns of chlorophyll-a or zooplankton distribution.
At the shallower Humber Bay LO8 station during June, the night profile displayed higher counts
in the epilimnion. As noted above, Humber Bay in June had a patch of elevated large
zooplankton counts (406-600 µm) which seem to be deeper in the water column during the day
(6m) and rise to the surface at night. The elevated night surface counts were still dominated by
the smallest size fraction which is likely comprised of veligers or copepod nauplii. During the
August sampling, the larger sized zooplankton fraction were absent within Humber Bay and
there is little change during the night for vertical zooplankton distribution. There were slightly
10
elevated counts throughout the water column of 300-405 µm size fraction at night which is likely
an influx of Bosmina or small copepods. The profile on Sept 9 during the Toronto survey clearly
shows a midwater intrusion of cold 7 °C water in the temperature profile related to the upwelling.
The zooplankton particle density reflects this with higher counts above and below the intrusion,
especially in the larger sizes >300 µm which occur in the water temperatures ~13-14°C. The
November profile is isothermal and cold (6°C) has very low zooplankton counts with no vertical
structure.
Other Surveys
There are few published surveys of Lake Ontario using Optical Plankton Counters (Sprules and
Goyke 1994, Sprules et al. 1998, Yurista et al. 2012). The results of Sprules et al. (1998) which
used the much older, lower-resolution light-beam instrument were focused on the calibration of
the size distributions with biomass and did not specifically survey the lake. The other LOPC
survey in Lake Ontario (Yurista et al. 2012) investigated the entire nearshore in September and
a portion of it during August 2008. The LOPC used was the first generation instrument which
has a minimum ESD size resolution of 150 µm, so misses the entire first size-bin of our survey
using the HR-LOPC which had the highest counts. This study was intended to examine the
broad landscape patterns of physical-chemical and zooplankton distribution and was not meant
to discriminate impacts on smaller regional scales due to the high variability found within the
measures. Also, the dominant drivers of the large-scale patterns were limited to temperature,
conductivity and chlorophyll-a. As such those methods are inappropriate to determine landeffects on plankton distributions for localized embayments such as Toronto Harbour or Humber
Bay (P. Yurista, EPA, personal communication, 2015, but see for more detail (Yurista et al.
2015)). Furthermore, the inshore cross-contour tows were only used to determine if the 20m
isobath transect was representative of the nearshore conditions, but it should be noted that the
inverse comparison is not applicable.
Summary and Conclusions
This survey was done to assist in the evaluation of the Degradation of phytoplankton and
zooplankton communities BUI (#13) for the Toronto Region AOC, currently classified as
requires further assessment in the Stage 1 analysis. This was a one-time survey during the
week of Sept 9-13, 2013 of the Toronto Region from Etobicoke to Pickering, which
encompassed the boundaries of the AOC. The intent of the survey was to determine the
distribution of zooplankton, chlorophyll and physical water characteristics using DFO’s towed
SHRIMP sensor array. To accentuate this spatial survey, for the 2013 Coordinated Science and
Monitoring Initiative (CSMI) year on Lake Ontario, station sampling was done for physical
characteristics, water chemistry, and collection of phytoplankton, microbial loop and
zooplankton for taxonomy which are being made available.
The results of the other LOPC survey in Lake Ontario (Yurista et al. 2012) that investigated the
nearshore were intended to examine the broad landscape patterns of physical-chemical and
zooplankton distribution and are not applicable for determining impact of local embayments or
river outputs into the coastal zone.
In September 2013, the entire Toronto coastline experienced a strong, widespread upwelling
during the period prior to this survey which greatly affected the distribution of physical
characteristics, chlorophyll, and zooplankton densities. In particular, the area near Ashbridges
Bay along the scarp was highly swamped by the upwelling making any determination of impact
by factors such as the sewage treatment outfall impossible for this survey.
11
Toronto Inner Harbour was very different than surrounding habitat in physical water
characteristics with elevated values for temperature, turbidity and chlorophyll. Sampling in 2013
and in other years suggests that Humber Bay experiences deep mixing and weak stratification,
likely due to its orientation to the northwest, which faces into the dominant prevailing wind
direction. Upwelling forces combined with the internal seiche of the lake is likely to create very
specific physical mixing conditions in Humber Bay that are unlikely to be found in any other
location within Lake Ontario, so comparisons to other embayments must use caution. Since the
dominant circulation within Toronto Harbour is from Humber Bay through the western gap any
assessment of the pelagic ecosystem should include stations within Humber Bay.
There were exceedingly low zooplankton particle counts in Toronto Harbour compared to the
surrounding Lake Ontario coast and other embayments of Lake Ontario. In particular, there
were very few large-sized zooplankton counts. Embayments within Lake Ontario typically have
much higher zooplankton densities than found in coastal habitats. This is likely not related to the
upwelling since the inner harbour shows even higher temperatures than found outside of the
upwelling in the lake, though there was hypolimnetic water from the lake intruding on the
western side of the harbour. Given the flushing rate of Toronto Harbour near 10 days (Haffner et
al. 1982), at these temperatures Cladoceran zooplankton should be able to reproduce several
generations before being flushed into the Outer Harbour and are likely able to retain themselves
against this flushing rate through vertical migration and active swimming (Genin et al. 2005,
Speirs and Gurney 2001), thus increasing the retention time. This suggests a possibility that the
inner harbour environment is currently not a suitable habitat for zooplankton populations.
Additional data on fish planktivory should be assembled to determine if this an interacting effect.
Further study should involve seasonal sampling of zooplankton to determine population
structure over the spring-fall period and possibly population growth studies using incubations
(Harris et al. 2000).
12
Section 1.2:
Toronto Harbour Zooplankton Sampling
K.L. Bowen
Introduction:
The Toronto and Region Area of Concern (AOC) covers a large geographical area on the
northwestern shore of Lake Ontario, extending from Etobicoke Creek in the West to the Rouge
River in the east (Environment Canada and Ontario Ministry of Environment, 2011). It includes
42 km of waterfront, and encompasses both the inner Toronto Harbour, the outer harbour
bounded by the Leslie Spit, and nearshore waters of Lake Ontario. One of the Beneficial Use
Impairments (BUIs) that has been identified in the Toronto AOC is the “degradation of
zooplankton and phytoplankton populations” (Environment Canada and Ontario Ministry of
Environment, 2011). Given the lack of available data on this subject, it has been given the
status of “needs further assessment”. The above report states that the key action that is
associated with this BUI is to “undertake an assessment of this environmental challenge and
develop a delisting target”.
The purpose of this report is to present and summarize the limited amount of zooplankton data
that is available to date. The primary focus will be reporting on two previously unpublished
studies conducted in 2010 and 2013 by the Great Lakes Laboratory for Fisheries and Aquatic
Sciences, part of Fisheries and Oceans Canada (DFO), Burlington Ontario. These spatial
studies provide a “snapshot’ of conditions in the Toronto area during the times of study. More
information on the rationale behind the 2013 survey is given in Section 1.1 of this report.
Methods
Background Information:
Despite its location adjacent to a large urban centre with research infrastructure, little has been
published on zooplankton in the Toronto Harbour area. One of the earliest and most
comprehensive studies of Lake Ontario was conducted from June to October 1967, and
included a detailed nearshore to offshore August survey in the Toronto area (Patalas 1969).
Patalas concluded that harbour water influenced Lake Ontario zooplankton populations in the
vicinity of Toronto, and suggested that pollution and local enrichment may have contributed to
these differences. Specifically, he reported higher nearshore densities of the predatory taxa
Leptodora (Cladocera) and Diacyclops thomasi (Cyclopoida) in the west and central areas off
Toronto, and depressed populations of the small cladoceran Bosmina, especially to the east.
Other lakewide studies have sampled coastal and offshore areas adjacent to Toronto (e.g., LO8
and LO9 in Figure 2.2). These include a 1970 study by Watson and Carpenter (1974), the LOTT
surveys of 1991 to 1997 (Morris and Sprules 2003, Johannsson 2003) and CSMI studies in
2003 (Holeck et al. 2008) and 2008 (Rudstam et al., 2015). However, none of these surveys
sampled inner or outer Toronto Harbour, nor reported specifically on individual stations in the
Toronto area. Since 1994, zooplankton in the inner harbour and several nearshore sites have
been sampled sporadically by the OMOE (see Section 2).
August 2010 Nearshore Study:
From 06 to 12 August 2010, a total of 43 nearshore stations were visited in western Lake
Ontario and adjacent embayments as part of a Fisheries and Oceans Canada (DFO) study on
nearshore plankton spatial distribution (Figure 2.1). Many of the coastal Lake Ontario stations
followed roughly along a 10 m depth contour. Nearshore to offshore transects were also
sampled in Burlington, Oakville, Port Credit, Grimsby, Humber Bay and Ashbridges Bay. Two
stations were located in Humber Bay (HB), five in the Inner Toronto Harbour area (IH), five in
13
the offshore area adjacent to Toronto Harbour (Off), and two in Ashbridges Bay (Ash) to the
east. This report will focus only on these 14 Toronto area stations. Coordinates and information
on these stations are given in Table 2.1. A summary of this information is being included but the
full details of the Lake Ontario Ecosystem Research Initiative (ERI) study will be published in a
forthcoming manuscript.
Chlorophyll a was measured in epilimnetic water from three stations, using the same methods
as described in Section 1.3 of this document. Secchi depth (an indication of water
transparency), station depth and a vertical profile with a fluoroprobe were taken at each station.
Water temperature, pH, conductivity and dissolved oxygen were taken at a depth of 1 m at each
station using a YSI 6600 multiparameter water quality sonde, and vertical profiles were taken at
selected stations. Surface water turbidity was measured using a LaMotte 2020e benchtop unit.
Zooplankton were collected at each station by taking a single vertical total water column (TWC)
net haul from 2 m off bottom to the surface, using a metered, 64 um mesh, 40 cm diameter
Wisconsin net. 14 samples collected in the Toronto area and 11 nearshore samples from the
western basin of Lake Ontario have been analyzed. Epilimnetic rotifers were counted from three
stations in the Toronto area (1364, 2047 and 431). For rotifers, 12 to 16 L of water were
collected from 0-5 m with an integrator bottle, narcotized with carbonated water and filtered
through 20 um mesh. Both zooplankton and rotifers were preserved in 4% sugar buffered
formalin. For both zooplankton and rotifers, counting and measuring procedures were based on
the stratified counting method of Cooley et al. (1986), using a minimum of 400 animals per
sample as outlined in Bowen and Johannsson (2011).
August 2012 Sampling
On 26 and 29 August 2012, TWC 64 µm mesh net hauls were taken at the mid-Toronto Harbour
stations (725 and 1364) (Figure 2.1). Other information collected included Secchi depth and
temperature, pH, conductivity and dissolved oxygen using a Hydrolab Minisonde 4A.
Toronto Harbour 2013 Surveys
From 09 to 13 September 2013, a spatial study of the Toronto Area of Concern (AOC ) was
undertaken by DFO to better understand plankton distributions within the region. Four stations
were sampled in Inner Toronto Harbour (IH), six in the nearshore (NS) between Humber Bay
and Ashbridges Bay (including one outer Harbour station), four in the adjacent offshore area
(Off), and five east of Toronto (East), including two in the Pickering area (Figure 2.2). In addition
to these point stations, a second vessel surveyed horizontal transects in the AOC using a towed
sensor, as described in Section 1.1.
At most of the point stations, water temperature, station depth, Secchi depth and light
attenuation using a Licor unit were taken. The latter two measurements were not possible at the
Pickering stations (708 and 1329) as these were sampled after sunset. If the station was
thermally stratified, zooplankton were collected from the epilimnion (epi), metalimnion (meta)
and hypolimnion (hypo, if present) using a 40 cm diameter, 64 µm mesh net (Table 2.2). A TWC
vertical net haul was also taken at each station using a 50 cm diameter, 153 µm mesh
Wisconsin style net. Stations deep enough for a hypolimnion to occur included LO9, TH4, AB3,
1326, 1329 and 708. Despite thermal stratification, only a single TWC 153 µm net was taken at
each of AB3 and TH4 in the offshore due to deteriorating weather and time constraints. The IH
stations and ST1 were only 8 to 10 m deep, and although a shallow epilimnion was present, the
epi and meta nets were pooled for analysis. Rotifers were collected at the stations indicated in
Table 2.2 using the same methods as in August 2010. All samples were preserved and counted
as in August 2010.
14
Additional 2013 zooplankton and rotifer samples were collected at LO8 (Humber Bay) and LO9
(offshore) on 12 June, 24 August and 21 October. This was part of DFO’s involvement in the
2013 Cooperative Science and Monitoring Initiative (CSMI) program in Lake Ontario (CSMI
2013 Coordinating Committee 2014). This was carried out in a similar manner as the September
spatial survey, and is summarized in Table 2.2. Additional TWC nets were also taken at these
stations on 14 August (153 µm) and 03 November (64 µm) as part of CSMI.
Results and Discussion:
Physical Parameters - August 2010:
Nine coastal stations in the Burlington Oakville (northwest) area were sampled on 06 August
2010, when surface temperatures averaged 20.4°C. An upwelling event occurred over the next
two days, and on 09 August, the surface temperature at K22 on the west side of Humber Bay
was only 16.9°C (Figure 2.3 top). By 11 and 12 August, this upwelling event was dissipating in
the Toronto area, and temperatures ranged from 19.2°C to 21.9°C (Table 2.1). Similarity in
temperatures between Inner Toronto Harbour and the surrounding areas suggest the Inner
Harbour is influenced by exchange of water from outside the harbour.
Turbidity was highest at stations 1364 and 725 in the Inner Toronto Harbour (Figure 2.3
bottom), likely due to loading from the Don River. Turbidity was also relatively high at K22
(Secchi depth = 2 m), probably due to discharge from the Humber River. Water clarity was
higher at TH1 and 726 on the western side the harbour, and at TH2 just outside the eastern
gap, probably due to exchange with the lake. Generally, water flows into Toronto Harbour from
Lake Ontario through the western gap and exits through the eastern gap (Haffner et al. 1982).
The Toronto Harbour stations were well oxygenated, with values above 9 mg L-1 throughout the
water column. Relatively efficient exchange of water with the lake, along with shallow water
depths in Toronto Harbour prevent strong temperature stratification and oxygen depletion from
occurring (Haffner et al. 1982).
Physical Parameters - September 2013
Thermal structure, surface temperatures, Secchi and light attenuation for the September 2013
cruise are detailed in Sections 1.1 and 1.3. An upwelling event took place during the survey,
with the coldest surface temperatures observed in the Ashbridges Bay area (e.g., 10.7°C at AB1
to 12.5°C at AB3). This compares to surface temperatures of 13.6 to 15.9°C at the remaining
nearshore and offshore stations, and 16.2 to 17.6°C in the Inner Harbour. The highest turbidity,
as indicated by Secchi depth, was observed at L12 and 1364 in the Inner Harbour, likely due to
the Don R. discharge, and HB3 near the mouth of the Humber River. Water clarity was greatest
in Ashbridges Bay where the upwelling was strongest, and at Etobicoke station 3508.
Zooplankton August 2010 Density, Biomass and Community Composition
In August 2010, the lowest mean zooplankton density was observed in Humber Bay at 9.7
±37.6 animals L-1 (Table 2.3; Figure 2.4 top). Mean densities at the remaining Toronto areas
ranged from 52.4 ± 59.8 animals L-1 in Ashbridges Bay to 57.3 ±14.0 animals L-1 in the Inner
Harbour. Dry biomass generally followed similar trends, with the highest values in the offshore
(105.8 ± 14.4 mg m-3), and the lowest in Humber Bay (18.2 ±10.4 mg m-3). Biomass in Inner
Toronto Harbour averaged 65.5 ± 5.5 mg m-3, which was within the range seen in the adjacent
nearshore areas. However, Toronto Harbour values were about an order of magnitude lower
than those observed in Hamilton Harbour or in the coastal nearshore of Lake Ontario during the
same survey. August zooplankton densities and biomass in central Hamilton Harbour are
15
typically two to three times higher than in Toronto Harbour (means of 106 animals L-1 and 138
mg m-3 from 2002 to 2012, respectively; K. Bowen, unpublished data). This indicates that
zooplankton in Toronto Harbour are less productive than expected. Residence time of water in
Toronto Harbour is about 10 days, compared to a much longer residence time of about 90 days
in Hamilton Harbour (Haffner et al. 1982). That study states that efficient water exchange with
Lake Ontario results in lower nutrient concentrations and algal biomass in Toronto than in
Hamilton, despite high nutrient loadings into each system. Effectively, the loading within Toronto
Harbour are exchanged with the nearshore of Lake Ontario, resulting in the dilution of
production over a larger area.
Both zooplankton densities and biomass values were unusually low at K22 near the mouth of
the Humber River and at 431, the shallowest station in Ashbridges Bay (Figure 2.4). The
reasons for this are unclear, but may have related to the upwelling event and/or flushing from
the river at K22. During an upwelling, nearshore water (and the animals within it) is temporarily
displaced by cooler hypolimnetic offshore water. As a result, upwellings can cause pronounced,
short-term changes in zooplankton populations, especially close to shore along exposed
coastlines (Haffner et al. 1984a).
In August 2010, zooplankton composition was somewhat variable throughout the nearshore
areas of Lake Ontario and Toronto Harbour, with cladocerans usually comprising between 48%
and 92% of biomass. The central Toronto Harbour station consisted of only 18% cladocerans.
Daphnia retrocurva was the most common cladoceran in the inner harbour, whereas the slightly
larger Daphnia galeata mendotae dominated Humber Bay and the offshore. Daphnia density
was highest in the outer harbour, with a mean of 16.2 animals L-1. This supports the idea that
zooplankton production is being exported by the circulation patterns in Toronto Harbour. The
small cladoceran Bosmina sp. was common in the inner harbour (11% by biomass), particularly
at station TH2 outside the Eastern Gap and 726 (Figure 2.4). The predatory Leptodora kindtii
was a dominant species in Humber Bay (20%), especially at station 2047. This station also
supported the highest biomass of another smaller predatory cladoceran, Polyphemus pediculus.
Predatory cladocerans comprised 52% of the total biomass at 2047. Total zooplankton biomass
was relatively low (28.6 mg m-3) at this station, possibly due to effects of high invertebrate
predation. In comparison, predatory cladocerans averaged only 5% at the remaining stations
(range: 0.1 to 15%). This included the invasive cladoceran Cercopagis pengoi, which never
exceeded 5% of the community by weight (mean = 8.9 mg m-3 or 1.2%).
Cyclopoid copepods were usually a minor component of the coastal Lake Ontario and Toronto
Harbour stations in 2010, comprising only 0.1% to 12% of the biomass. The highest cyclopoid
biomass value was 5.2 mg m-3 at TH4. Copepodids (juveniles not identified to a lower taxonomic
level) and Diacyclops thomasi were most commonly encountered. Calanoid copepods
represented between 0.4% and 18% of the total biomass, and were dominated by copepodids
and adult diaptomid copepods. Calanoids are normally indicative of cooler, less productive
offshore waters, and their biomass averaged only 1.5 mg m-3 or less at the inner harbour,
Humber and Ashbridges areas. In coastal Lake Ontario, the highest calanoid biomass values
were observed at the deepest stations, TH4 and TH5 (23.1 and 12.0 mg m-3, respectively).
Veligers, the pelagic larvae of invasive dreissenid mussels, were numerically the most dominant
taxa at most of the 2010 stations, with densities in the Toronto area ranging from 0.4 to 88.5
animals L-1 (Figure 2.4). Although variable, they were particularly dominant at the mid-Toronto
Harbour station 1364 and 909 in Asbridges Bay. Due to their small size, they were less
dominant in terms of biomass, but still averaged between 1% (0.3 mg m -3) at 2047 in Humber
Bay and 79% (64.8 mg m-3) at 1364. Although biomass in the Inner Harbour was variable, it
16
averaged 20.5 mg m-3 (28%). Most of those in the open water were likely Quagga mussel larvae
(Dreissena bugensis), but zebra mussel larvae (D. polymorpha) may be found in the nearshore
and harbour areas adjacent to hard substrates such as breakwalls and piers.
Late August 2012 - Density, Biomass and Community Composition
On 29 August 2012, water temperature was 21.3 C and Secchi depth was 1.5 m in mid-Toronto
Harbour. Zooplankton density and biomass averaged 25.6±3.8 animals L-1 and 42.7±5.1 mg m-3,
respectively (Table 2.3). In terms of biomass, the community was dominated by cladocerans
(93%), which was the highest proportion of this group at any site in the three surveys reported
here. The dominant cladocerans were D. retrocurva (25%) and Holopedium gibberum (25%).
Holopedium has a gelatinous sheath which can make it more resistant to invertebrate predators
(Yan and Pawson, 1997), and can be abundant in the open water of Lake Ontario in late
summer. Copepods and veligers comprised only a small portion of the biomass in Aug. 2012.
2013 Toronto Area Surveys - Density, Biomass and Community Composition
Although the epi, meta and hypo samples were generally counted separately at the deeper
stations in 2013 (Table 2.2), the values presented below and in Table 2.3 are depth-weighted
means for the TWC (i.e., the proportion of the water column occupied by each depth strata was
taken into account when calculating the mean value). Both the epi and total water column
density and biomass values for these stations are plotted in Figure 2.5. No consistent
relationships between the epi and TWC values were evident, and community composition often
differed between the two estimates. Unless specified otherwise, values presented below are for
the TWC.
During the September 2013 spatial survey, mean zooplankton density and biomass were very
low in the Inner Harbour and the nearshore surrounding the harbour, with values ≤12 animals L1
and ≤8.3 mg m-3, respectively (Table 2.3, Figure 2.5). These Inner Harbour zooplankton
populations were substantially lower than those observed during the 2010 and 2012 August
surveys. The Inner Harbour was dominated by cladocerans (62% by biomass), especially
Bosmina sp. and D. retrocurva, and cyclopoid copepods (18%). Cyclopoids were somewhat
more dominant in the nearshore (26%). In Sept. 2013, mean zooplankton biomass was
intermediate in the offshore (41.5 ±11.8 mg m-3) and highest at the eastern stations (74.3 ±33.9
mg m-3). Cladocerans were less dominant in these areas, comprising <40% of the biomass.
Cyclopoid copepods were the most dominant group in the offshore and east in Sept. 2013,
comprising 61% and 42% by biomass, respectively. These were predominantly D. thomasi and
juveniles. Cyclopoid biomass values were variable among sites, with the highest level at station
1325 in the east (122.6 mg m-3). Values at the remaining offshore and east stations ranged
between 7.4 and 57.3 mg m-3, but <3 mg m-3 at the Inner Harbour and nearshore sites. Nauplii
(larval copepods) were abundant at the eastern stations in 2013, but comprised only a small
portion of biomass due to their very small size. Cyclopoids were much less dominant in 2010
and 2012, with biomass comprising ≤6% at all sites except Hamilton. Cyclopoid densities at all
the Toronto area sites averaged 8.2 ± 3.6 animals L-1 in Sept. 2013, compared to only 2.8 ± 0.6
animals L-1 in Aug. 2010. This appears to reflect a lakewide trend in increased cyclopoid
abundance in 2013, and will be explored in more detail through the CSMI program.
Calanoid copepod biomass was low at all sites in Sept. 2013 (<5 mg m-3). The proportion of
calanoids was highest in the east (8%), especially at the Pickering area sites which were
sampled at dusk. The large, deep water calanoid Limnocalanus macrurus and the diaptomid
calanoids were uncommon at all sites, but generally these taxa were most abundant at the
deeper stratified sites. The presence of Limnocalanus at shallow site LO8 in Humber Bay,
17
coupled with the very low total zooplankton biomass at this station, was likely caused by the
upwelling event observed during the survey.
Veliger larvae were generally less abundant in September 2013 than in 2010, averaging 9.0 ±
3.5 animals L-1 and 30.4 ± 7.5 animals L-1 at all study sites, respectively. However, they still
represented 33% by density and 17% by biomass in the Inner Harbour in 2013. Veliger density
and biomass values were highest at AB1, at the edge of the upwelling site (66.9 animals L-1 and
14.2 mg m-3, respectively), although biomass was ≤3.0 mg m-3 at most sites.
It is interesting to note that zooplankton populations were particularly low at AB2 in Ashbridges
Bay in September 2013 (2.4 animals L-1), possibly due to the dilution effects of the upwelling
event at this station. In August 2010, this area also supported the lowest densities of
zooplankton (2.9 animals L-1 at 431) though any upwelling effect was minimal at this time (Fig.
2.3). The Toronto Main Sewage Treatment Plant discharges effluent in the vicinity of this
station. Daphnia toxicity laboratory studies conducted by Munawar et al. (1993) showed
decreased survival in water overlying sediment collected from 431. Even in August 1967,
Bosmina densities also appeared to be depressed on the east side of Toronto (Patalas 1969).
Seasonal and Temporal Trends
There were strong seasonal trends in zooplankton populations at LO8 (Humber Bay) and LO9
(offshore 60 m), the two Toronto area stations sampled repeatedly in 2013 as part of the CSMI
program (Figure 2.6). Biomass was low in June, and consisted mostly of cyclopoids and
veligers. Values increased to the highest levels in August 2013 at both stations. Biomass
peaked at 106.4 mg m-3 at LO8 on 24 August, but was only 4.6 mg m-3 two weeks later during
the upwelling. The August community was dominated by Bosmina, Eubosmina and cyclopoid
copepodids. Similar trends were observed at LO9, although the drop in TWC biomass was not
as dramatic (56.2 mg m-3 on 14 August, compared to 19.5 mg m-3 on 09 September). In the
epilimnion (epi) at LO9, biomass of veligers and bosminids were much higher on 24 August than
in September, although Daphnia, predatory cladocerans, other cladocerans and cyclopoids had
increased in September. TWC biomass was similar at the two stations in September and
October, although the community was dominated by calanoid copepods later in the fall.
Seasonal results from the 2003 and 2008 CSMI programs (Holeck et al. 2008, Rudstam et al.
2015) are included in Figure 2.6 for comparison. Unfortunately veliger data were not available
for the TWC in 2003 and 2008, as these were sampled with a 153 µm net that does not
effectively retain veligers. In 2003, TWC zooplankton biomass was very low at both LO8 and
LO9 in April, and peaked in late September, with a value of 106.6 mg m-3 at LO9. Cyclopoid
copepods were a dominant part of the community in August and September. Daphnia were also
abundant in the TWC at LO9 in September, and the predatory cladoceran Cercopagis was
dominant at both stations in August. Epi veliger biomass was relatively low. In 2008, community
composition had changed dramatically (Rudstam et al. 2015), with a drop in cyclopoid biomass
and an increase in veligers in the epi. Calanoids were dominant at LO8 in April and the LO9
TWC samples in July and September. Cyclopoids had regained importance in the TWC in June
and August 2013. As cyclopoids are predominantly found in the meta and hypo, epi zooplankton
composition was similar in July 2008 and August 2013 at LO9.
Zooplankton was also sampled every three years at nearshore index sites in Lake Ontario by
the Ontario Ministry of Environment (OMOE) starting in 1994 (see Section 1.2). Samples were
collected at three depths through the water column using a Schindler-Patalas trap in spring,
summer and fall in 1994, and every three years starting in 2000. The three traps from each
station-date were pooled and counted using the same methods described in this report. The
18
stations in the Toronto area included Etobicoke (3508) in 2006 and 2009, five years at Humber
(LO8) and Inner Toronto Harbour (1364), and at Pickering (708) from 2000 onwards (Figure
2.7). In summary, the highest zooplankton biomass value was observed at LO8 in August 1994
(336 mg m-3) due to a population spike. On this date, the community was comprised primarily of
bosminids, cyclopoids and Daphnia. Densities at LO8 on August 1994 and August and October
2000 ranged between 70 and 151 animals L-1, but were otherwise below 30 animals L-1 at all
stations. The highest biomass values in the Inner Harbour were observed on August 1994 (45.6
mg m-3) and August 2009 (58.9 mg m-3), due to a large number of Daphnia. Cyclopoids and
bosminids were also high on these two dates, respectively. Otherwise, zooplankton biomass
values were usually very low (below 25 mg m-3) at these four stations. For the remaining 2006
and 2009 samples, biomass values for cyclopoids, bosminids and veligers were generally low,
though veligers were at times numerically abundant. Calanoid biomass tended to increase at all
stations in 2009. Daphnia and predatory cladocerans (primarily Cercopagis) were periodically
important during the summer.
In comparison, the total biomass value during the September 2013 survey (dashed lines in
Figure 2.7) at LO8 was substantially lower than values observed during the previous index
surveys by OMOE, but the reverse was true at the Etobicoke site. The Inner Toronto Harbour
and the Pickering sites fell within the index sample range for some summer dates. This further
illustrates the inter-annual variability at the Toronto area stations.
The dramatic seasonal trends observed in 2013, accompanied by inter-annual variability over
the last two decades, illustrate the difficulty in trying to quantify zooplankton populations in a
given area based sporadically on only one or two surveys. The 2013 spatial survey only shows
a snapshot in time, and results would likely have been quite different if the survey were carried
out even two weeks earlier. These results support the idea that sampling should be carried out
on a more frequent basis (biweekly to monthly) at one or two stations, and accompanied by a
small number of spatial surveys to better understand spatial variability in the study area.
Cladoceran Mean Size
The mean length of herbivorous cladocerans, and Daphnia specifically, can be used as an
indicator of fish predation rates (Brooks and Dodson 1965, Mills et al. 1987) or disruptions to
large cladoceran reproduction. Planktivorous fishes such as alewife, white perch, and the
juveniles of many species such as yellow perch and various sunfish, selectively target larger
individuals (Brooks and Dodson 1965, Cooley et al. 1986). When planktivory rates are high, the
mean size of cladocerans is often suppressed and the community is dominated by smaller
species. In August 2010, cladoceran length averaged 781 µm in the open lake, compared to
631 µm in the Inner Harbour and Humber Bay (Figure 2.8). By Sept 2013, means had dropped
to 520 µm in the east and offshore, and 373 µm in the Inner Harbour and nearshore. Both
herbivorous cladocerans and Daphnia were uncommon in the latter two study areas in 2013
(Figure 2.8). Furthermore, mean cladoceran size was usually below 500 µm at LO8 and LO9
during the 2013 CSMI sampling season (Bowen, unpublished data). The few Daphnia that were
present in the inner harbour in Sept. 2013 tended to be the same size or slightly larger than
those in 2010. This suggests that the loss of Daphnia, rather than a change in size of those
present, was the primary driver in the drop in mean cladoceran size.
Declines in Daphnia abundance and the decrease in mean cladoceran size both suggest higher
rates of planktivory in 2013 than in 2010, especially in the harbour and nearshore. Alewife is the
primary planktivorous fish in Lake Ontario (Johannsson and O'Gorman 1991, Rand et al. 1995).
In 2010, adult alewife abundance in the U.S waters of Lake Ontario reached its lowest level
since 1978, but by 2013 had recovered to levels more consistently seen during the 2002 to
19
2012 period (Walsh et. al. 2014). This same study indicates that yearling alewife in 2013 hit the
highest level observed in southern Lake Ontario since 1978 when monitoring began. Alewife
was also the dominant species in Humber Bay during the 2013 CSMI fish surveys in both trawl
nets and vertical gill nets, followed by rainbow smelt (trawl nets) and emerald shiner (gill nets)
(Milne, 2014). Toronto Harbour electrofishing surveys by DFO in 2009 also found alewife to be
the most abundant species, followed by yellow perch, emerald shiners and white suckers (C.
Boston, unpublished data). The Ontario Ministry of Natural Resources and Forestry’s Nearshore
Fish Community Index Trap Netting program in the Toronto Harbour area from 2006 to 2012
indicates that brown bullheads are the most dominant species in terms of numbers, followed by
pumpkinseed, yellow perch and alewife (Hoyle 2013). This gear targets fish >90 mm, so would
not capture many smaller planktivorous species such as younger alewife or shiners.
Rotifers
Rotifers were enumerated from three epi samples collected in August 2010 and five in
September 2013 (Figure 2.9). Rotifers can be very numerous in the water column (e.g. up to
630 animals L-1 at 431 in August 2010), but due to their very small size their contribution to total
biomass is generally considerably less than that of zooplankton. However, their parthenogenic
reproduction rates are often rapid, and they may be consumed by predatory zooplankton such
as Cercopagis (Makarewicz and Lewis 2015, Pichlová-Ptáčníková and Vanderploeg 2009) and
cyclopoid copepods (Stemberger 1986). Rotifers can play an important role in energy and
nutrient transfer in the aquatic food web (Makarewicz and Likens, 1979). Rapid turnover rates
also mean that rotifer species can quickly bloom and disappear, and large pulses may be
missed by infrequent sampling. The most abundant rotifer taxa in the Toronto area samples
included Polyarthra vulgaris, Keratella cochlearis, Synchaeta kitina and Conochilus unicornis.
Because it is so large, Asplanchna sp. often dominated rotifer biomass even when numerically
uncommon. These taxa tend to be common throughout Lake Ontario (Makarewicz and Lewis
2015). Rotifer densities in Toronto Harbour averaged 334.5 animals L-1 in 2010 and 170.3
animals L-1 in 2013.
The highest rotifer biomass values were observed at stations 1364 and 431 in 2010, with values
around 6 mg m-3 at each station). Rotifers comprised 11% and 43% of the total zooplankton +
rotifer biomass at these two stations, respectively, but only 3% at the Humber Bay station 2047.
In September 2013, rotifer biomass ranged between 1.6 mg m-3 at LO8 and 3.4 mg m-3 at 708
off Pickering, showing an increasing west to east gradient. Rotifers comprised the highest
proportion of rotifer + zooplankton biomass at LO8 (17%) and the inner harbour station 1364
(15%), and <8% at the remaining stations. The percent contribution by rotifers tended to be
higher in the Toronto Harbour area than in the more productive embayments of Lake Ontario,
although the biomass values were in the same range. For example, seasonal mean rotifer
biomass in the upper and middle reaches of the Bay of Quinte averaged 2.6 mg m-3 over the
2000 to 2008 period, representing only 2% to 4% of total zooplankton biomass (Bowen and
Johannsson 2011).
Rotifers also show seasonal and inter-annual trends in biomass and species composition
(Figure 2.10). At LO8 in July 2008, rotifer biomass was high (27.6 mg m-3 or 43% of total
zooplankton + rotifer biomass), and was dominated by the large taxa Synchaeta grandis and
Asplanchna sp. By September 2008, these two taxa had largely disappeared and biomass had
declined to 6.0 mg m-3. However, this still represented 25% of the total biomass. In 2013, rotifer
biomass stayed below 1.7 mg m-3 on all four dates sampled between June and October (Figure
2.10), reaching its lowest levels in the late fall. Because zooplankton biomass was low in
September, rotifers represented 27% of the total. Contribution by rotifers dropped to only 0.6%
20
on 24 August when zooplankton biomass was very high. Synchaeta kitina was the dominant
taxon in June, although the community was more diverse on the other 2013 sampling dates.
Summary and Conclusions:
The limited zooplankton data available from inner Toronto Harbour have shown strong spatial
and temporal variability over the last decade. Although more data are available for the
nearshore zone of Lake Ontario adjacent to Toronto Harbour, it too shows seasonal variability
associated with seasonal succession of zooplankton species, and longer term changes in
zooplankton community structure in Lake Ontario (e.g., Rudstam et al. 2015, Johannsson
2003). These fluctuations are associated with changes in nutrients and phytoplankton, invasive
species such as dreissenid mussels and predatory cladocerans, and changes in planktivorous
fish populations (Sprules 2008). Although variable, zooplankton populations in the inner Toronto
Harbour and adjacent nearshore tend to be lower than in other embayments in Lake Ontario
such as the Bay of Quinte (Bowen and Johannsson 2011) or Hamilton Harbour (Dermott et al.
2007). Relatively low zooplankton populations in the Toronto Harbour area and Humber Bay
may relate to high fish predation pressure, coupled with flushing from rivers and elevated water
exchange with Lake Ontario. Upwelling events appear to be common phenomena in the Toronto
area based on prevailing wind directions and basin morphology (Lee 1972), and may depress
local zooplankton populations (Haffner et al. 1984a). Low zooplankton densities in the
nearshore area of Ashbridges Bay have been noted on several occasions, and although
reasons are uncertain, the role of the Ashbridges Sewage Treatment Plant should be
investigated further. In conclusion, two late summer spatial surveys are not adequate to properly
assess the zooplankton and phytoplankton degradation BUI in the Toronto AOC, and more
intensive temporal sampling is required to address this issue. Although not conclusive, these
results suggest that further examination of the effects of Toronto sewage discharge on
zooplankton populations may be warranted.
21
Section 1.3:
Toronto Harbour Water Chemistry, Physical Conditions, Phytoplankton and Microbial
Loop
H.A. Niblock
Background: Toronto and Region AOC
Toronto and Region is one of 43 locations across the Great Lakes designated as an Area of
Concern (AOC) under the 1987 Great Lakes Water Quality Agreement (GLWQA) between
Canada and the United States. An AOC is an area having experienced high levels of
environmental harm due to human activities. Fourteen Beneficial Uses were evaluated in each
AOC and if considered impaired a Remedial action plan was developed. The Greater Toronto
Area (GTA) is the largest urban area in Canada, with a population of about 6 million people.
Since the earliest settlements on Lake Ontario, agricultural and urban developments have
dramatically reshaped the natural environment of the region. The shape of Toronto Harbour has
changed dramatically with infill and river diversion altering the nearshore environment.
Contaminants from stormwater runoff and melting snow have impacted the waters of Lake
Ontario. Of the 14 potential Beneficial Use Impairments (BUIs) Toronto and Region, 8 BUIs
were identified as ‘impaired’, five considered ‘not impaired’ and one ‘requiring further
assessment’. In Toronto and Region AOC the unknown BUI is degradation of phyto- and
zooplankton populations. As in most of the Great Lakes AOCs, there was very little known about
phytoplankton and zooplankton in the area and so evaluators were unable to say if their
populations in the AOC were degraded relative to surrounding ‘non AOC’ areas. When the 2012
renewal of the GLWQA reaffirmed the commitment to restoring water quality and ecosystem
health in the AOCs, an attempt to understand the phytoplankton and zooplankton populations in
this AOC was initiated.
This report is an attempt to summarize the available historical data on phytoplankton and to
present a snapshot of the phytoplankton community in and around the harbour in September
2013. This information is intended for publication. Do not distribute without permission.
Historical study of phytoplankton and microbial loop
Nalewajko (1966) published the earliest studies of the phytoplankton in the current Toronto and
Region AOC. Surface samples were taken from a station 1km south of Gibraltar Point at 1-8
week intervals in 1964 and 1965. Unfortunately the nanoplankton was not enumerated and so
seasonal trends are shown for the larger taxa only. Of 36 taxa with abundance reported; 17
were Diatoms, 15 were Chlorophyta, 1 was Chrysophyceae, 1 was Dinophyceae and 2 were
Cyanophyta.
The most extensive studies on the phytoplankton of Toronto Harbour and surrounding area
were by Haffner et al. (1982, 1984b). Samples were collected weekly from a mid Harbour
station from May to October, 1977 and at 3 stations (5m, 12m & 30m depth) off of Scarborough
and Clarkson in May to December, 1979. The inner harbour was found to have between 1-2 g
m-3 with a maximum of 5 g m-3, while the outer harbour, nearshore area was found to have a
similar range of biomass. The outer harbour was found to be predominantly Diatomeae,
Cryptophyceae and Chlorophyta, while in the inner harbour Diatomeae dominated in the spring
and Cryptophyceae and Chlorophyta were dominant the rest of the season. Haffner et al.
(1984a) concluded that the hydrology of the area is highly complex given upwelling, coastal jets,
internal waves and thermal bar formation along with frequent meterorological changes, and that
the coastal zone in this area is not a steady state environment.
22
In July 1985 Munawar et al. (1989a) conducted a study on the impacts of dredging and dumping
dredged materials on the phytoplankton in Toronto Harbour. The natural phytoplankton
communities reported in control measures (pre dredge or dump) show a biomass dominated by
phytoflagellates, specifically Cryptomonas erosa Ehrenberg and Uroglena Americana (Calkins)
Lemmerman. Unfortunately, total biomass was not reported. Bioassays conducted using natural
phytoplankton populations showed that the rates of primary productivity of indigenous
phytoplankton populations increased during and following dredging operations. At the time
dredging was estimated to be ongoing for 270 hours a year in Keating Channel. Dredging also
caused changes in nutrient and trace metal concentrations. Generally, a decrease in some
nutrient concentrations was observed which is explained by enhanced productivity to biomass
(P/B) quotients during dredging.
In 1986, Toronto Harbour sediments were used in a bioassay methods trial (Munawar et al.
1989b) and it was observed that exposure to increasingly higher sediment levels in the bioassay
caused the phytoplankton community to have a significantly reduced rate of productivity.
In 1987 and 1988, bioassay work was conducted to test for the effects of a change in the
Ashbridges Bay sewage treatment plant (STP) operations upgrades on the phytoplankton of
Ashbridges Bay (Munawar et al. 1993). Rates of primary productivity were measured at the STP
outflow, around the outflow area and along an offshore transect. Rates of productivity ranged
from less than 1 to over 7 mg C m-3 hr-1 in November; from 15-80 mg C m-3 hr-1 in March; and,
9-80 mg C m-3 hr-1 in April. Rates less than 5 mg C m-3 hr-1 are consistent with oligotrophic
conditions (Munawar et al. 2013), while rates over 50 mg C m-3 hr-1 are seen in the eutrophic
embayments of Bay of Quinte and Hamilton Harbour (Munawar et al. 2012). The microbial loop
was shown to have significantly less autotrophic picoplankton (APP) in the Bay compared to the
offshore while bacteria and heterotrophic nanoflagellate (HNF) levels were similar. Cluster
analysis of ciliate taxa data showed that the STP outflow station was different from the other
stations in all samples. Sediment bioassays run using offshore phytoplankton showed that
sediments from the STP outflow inhibited ultraplankton (>20 µm in size) productivity rate but this
influence was restricted to the outflow station itself and effects were diluted in the immediate
area.
The STP outflow station and stations along an offshore transect (southeast from Ashbridges
Bay) had phytoplankton counts completed from July, August and October 1988 (Munawar
unpublished data). In July and August, the STP outflow station has much more phytoplankton
biomass than the other stations. In July peaks in Diatomeae (Tabellaria fenestrata (Lyngb.)
Küetzing and Melosira islandica O. Muller) and the Euglenophyta genus Colacium accounted for
45% of the 16.5 g m-3 biomass. During the same survey, biomass ranged from 0.8-3.4 g m-3 at
other stations. In August, 33% of the 9 g m-3 biomass found at the STP site was a Euglenoid
spp. not seen at the other stations where biomass was much lower. At the other stations
biomass ranged from 2.3 to 2.8 g m-3 and was a mix of Chlorophyta and Dinoflagellates. In
October 1988 the biomass at the STP site was in line with the other stations measured (1.9 to
4.3 g m-3) and was a similar mix of Chlorophyta, Dinophyceae and Cryptophyceae.
In October 1991 and September 1992 taxonomic data were collected on the phytoplankton,
ciliates and microbial loop in the Inner Toronto Harbour, Ashbridges Bay and an offshore
transect (Munawar et al. 2003). In October 1991, phytoplankton biomass in the Toronto region
was one half of that of the offshore transect (although highly variable between stations). Inner
harbour phytoplankton biomass ranged between 0.2 to 2.9 g m-3, Ashbridges Bay phytoplankton
biomass ranged from 0.4-2.6 g m-3 and offshore biomass ranged from 1.2-7 g m-3 (Munawar et
al. 2003). Composition was a mix of Diatomeae and Cryptophyceae in all regions.
23
Ciliate biomass was also highly variable during the October 1991 survey. Average ciliate
biomass in the inner harbour (20-1800 mg m-3) was high compared to the outer harbour (50-550
mg m-3) and offshore transect (20-70 mg m-3, Munawar et al. 2003). Microbial loop biomass was
similar in the nearshore and the offshore and the previously reported trend of low APP in the
Toronto area was only seen at the STP outflow and the mouth of the Don River, the sites
expected to be most impacted by urbanization. Bacteria and HNF values were similar among
areas (Munawar et al. 2003).
MOE dataset
The Ontario Ministry of Environment and Climate Change collected phytoplankton samples from
nearshore stations around the Great Lakes, in spring, summer and fall, approximately every
three years as part of their Great Lakes Nearshore Index Station Network program. Samples
were recently counted for phytoplankton biomass and composition and those collected from the
inner Toronto Harbour and mid Humber Bay in the summers of 1994, 2003, 2006 and 2009 are
presented in Fig. 3.1. Biomass was highly variable and ranged from 0.01 – 0.9 g m-3 in Humber
Bay and from 0.01-2.2 g m-3 in the inner Toronto Harbour. Average summer biomass in Humber
Bay was 0.54 g m-3 and the average biomass in the Inner Toronto Harbour was 0.68 g m-3. Both
of these are in the ultra- oligotrophic range of Munawar and Munawar (1982). The range of
biomass values was extremely high and the greatest difference in biomass occurred between
the two samples taken in 1994 only a month apart where they ranged from ultra-oligotrophic to
mesotrophic. The highest biomass was found in August 1994 and this was primarily due to a
peak in the large Dinophyceae taxa Ceratium furcoides and C. hirundenella. In recent samples
the inner harbour appeared to be a mix of groups including Diatoms and Cryptophyceae. The
Phytoplankton community in Humber Bay has been variable over time, but has had more
Chrysophyceae in the most recent samples.
Current Study: Methods
A synoptic survey of the Toronto Harbour Area of Concern and nearby nearshore Lake Ontario
was conducted the week of September 9, 2013 in conjunction with the spatial mapping
described in Section 1.1. Traditional point sampling techniques were used to collect data
comparable with previous sampling undertaken by DFO. Point sample parameters included
profiles using an YSI EXO2 sonde (temperature, depth, dissolved oxygen, pH, conductivity,
turbidity, salinity, chl a, phycocyanin and fDOM fluorescence sensors) and algal pigments using
a FluoroProbe (bbe Moldaenke). Attenuation of photosynthetically active radiation (PAR) was
measured with a Licor quantum sensor.
Temperature profiles were used to determine stratification and integrated sampling depth.
Epilimnetic water samples were collected with a bottle integrator from the surface to a maximum
of 8m or 1 m off bottom depending on stratification and bottom depth. The station was
considered unstratified if the thermocline was less that 5m deep. Integrated water was stored in
the dark and on ice and was pre-processed (filtered) the same day for water chemistry
parameters, which were submitted to Environment Canada’s National Laboratory for
Environmental Testing. Analysis of total phosphorus (unfiltered), soluble reactive phosphorous,
nitrite and nitrate, ammonia, total Kedjal nitrogen, dissolved organic and inorganic carbon,
particulate organic carbon and nitrogen, silica, calcium, sodium, potassium and magnesium was
undertaken. To determine chlorophyll a, water was filtered onto G/FC filters and frozen prior to
acetone extraction and spectrophotometric reading (Strickland & Parsons 1968).
Subsamples of integrated water were preserved using acidified Lugol’s iodine solution for
phytoplankton and ciliate identification. Phytoplankton enumeration and measurement followed
the HPMA (2-hydroxypropyl methacrylate) technique described by Crumpton (1987) and is
24
broadly compatible with the Utermöhl (1958) inverted microscope technique. Ciliate samples
were post-fixed with Bouin’s fluid and enumeration and identification followed the Quantitative
Protargal Staining technique (Montagnes and Lynn, 1993). Microbial loop (bacteria,
heterotrophic nanoflagellates and autotrophic picoplankton) samples were preserved in 1.6%
formaldehyde and processed using DAPI staining and epifluorescent microscopy (Porter and
Feig, 1980).
Size-fractionated primary productivity (Munawar et al. 1989c) was estimated using the 14C
uptake technique (Vollenweider et al. 1974). Integrated water (as collected for water chemistry)
was inoculated with NaH14CO3 and was divided into 100 ml portions and placed in four 200ml
polycarbonate flasks. Each sample was then incubated for four hours at constant and optimal
light levels of 238 µE/m2/s at 400-700 nm while being maintained at lake temperature. After the
incubation period, the contents of each bottle were size-fractionated through 20 µm Nitex
screen. The large material caught on the screen was back-washed onto a 0.45 µm Millipore
membrane filter. This determined the netplankton productivity (>20µm). The portion of the
sample that passed through the 20µm Nitex screen was filtered directly onto a 2µm Millipore
membrane filter which determined nanoplankton (2-20µm) productivity. The left over sample
was then filtered using 0.45µm Millipore membrane filters to determine the picoplankton
productivity (<2µm). The membrane filters were then acidified with 10ml of 0.1 N HCl and kept
in a Phase Combining System (PCS) for liquid scintillation counting (Lind & Campbell, 1969).
Uptake rates of leucine from a whole water sample were used to determine the maximum
potential bacterial carbon production following the procedure outlined by Jorgensen (1992).
Bacteria are known to take up amino acids from their environment and amino acids are known
to be present in modest amounts. Although some algae are heterotrophic, by far most of this
heterotrophic activity is bacterial. The bacterial uptake constant Kt for leucine is generally about
10 nM, so they are not living in a "saturating quantity" of leucine and they are not taking it up at
Vmax, the maximum rate. In this procedure we add sufficient leucine to bring the concentration
to "saturation", and incubate for one hour at surface temperatures to measure Vmax. Therefore
we measure "potential" production rather than actual production.
Sampling moved from west to east, starting with Humber Bay on Monday, inner and outer
Harbour on Wednesday and Ashbridges Bay to Pickering on Friday. Due to time and monetary
constraints a subset of the stations sampled for physical parameters were chosen for water
chemistry and plankton parameters. Stations were picked to represent a nearshore to offshore
transect in Humber and Ashbridges bays and wide spatial coverage in the inner harbour (Table
3.1).
As part of the Lake Ontario 2013 Cooperative Science and Monitoring Initiative (CSMI) program,
comparative data were also collected from 2 stations on the Humber Bay transect (mid-shore
LO8 and offshore LO9) in the late spring (June), once in summer (August) and in twice in the fall
(October and November) of 2013. A wide swath of stations were also sampled in and around
Toronto Harbour in August 2010 as part of a DFO Lake Ontario nearshore study (see table 2.1
in the zooplankton section 1.2 for coordinates and sampling details).
Results
Physical parameters: Thermal structure
September 2013
The thermal structure was assessed using an YSI EXO2 water profiler (or MK9 datalogger if the
EXO2 profile was not available) and most stations were found to have complex stratification with
a series of steps or stable temperature lenses lying over other layers and divided by transition
zones. The transition zones often comprised a large portion of the water column. Howell et al.
25
(2012) documented these complex thermal profiles along the north shore of Lake Ontario and
attributed them to strong onshore-offshore circulation. Fig. 3.2 shows there was more layering in
the eastern and western gap areas, were water from the lake was able to intrude into the
warmer harbour area, than in the mid-harbour or offshore. The mid-harbour and Don River
stations were warmest overall and were fairly stable as the entire water column was over 15°C.
Stations in the inner and outer harbour as well as the off shore stations in the west and far east
(Pickering) had surface temperatures (ST) over 15°C (Table 3.1). The near and mid-shore
stations off Pickering and off Port Credit showed the influence of a recent upwelling event which
are common on the north shore of Lake Ontario (Miners et al. 2002).As a result, surface
temperatures were cooler than expected (13-15°C) for late summer in Lake Ontario (Dobiesz
and Lester 2009). Nearshore Ashbridges Bay stations were isothermal due to upwelling and
were less than 11°C for the entire water column. The 3 deepest stations had large portions of
the water column that were unstable temperature transition zones (35-45%) and were the only
stations with hypolimnion temperatures below 5°C.
Aug 2010
The thermal structure in August 2010 was measured using the FluoroProbe and showed no
complex stepping (Fig. 3.3) as was seen in the 2013 survey. The majority of stations were
shallowly stratified (epilimnion less than 10m deep with temperature greater than 19°C) and had
a large sloped metalimnion (zone of temperature change) that continued right to the bottom.
This pattern applied to inner and outer Toronto Harbour. Overall the surface temperatures seen
in August 2010 were higher and more uniform than in the 2013 survey.
Seasonal 2013
Typically LO8, the 14m mid-shore Humber Bay station, was not found to be stratified and
showed only surface warming in mid-June (around 3.5m) and late August (complex stepped
layering in top 8 m). Surface water temperature was warmest in August at 18°C and coolest in
early November at 5.5°C. Station LO9, the 60m deep station, showed complicated stratification
patterns. It was warming in the June cruise with a surface temperature of 12°C and 4 layers of
water, by August these lenses were more pronounced and by early September the area was
fully stratified (surface temperature =18°C). Offshore station LO12, at 100m, was distinctly
stratified in June (ST=11°C), August (ST=18°C) and October (ST=10.7°C) and fully mixed in
November (ST=4.6°C). Increased chlorophyll fluorescence was associated with each
thermocline at the 60 and 100m stations.
Physical parameters: Light Attenuation
September 2013
The euphotic zone (Zeu1%) is defined as the photosynthetically active zone from the surface to
where only 1% of incidental or surface light is available, and the depth of this zone decreases
with increasing light attenuation (i.e., higher turbidity). Attenuation (EPAR) of photosynthetically
active radiation (PAR) was measured with a Licor quantum sensor (Table 3.1). Average
attenuation was higher in the west (0.291 m-1 ±0.005) than in the east (0.222 m-1 ±0.004) and
was highest in the inner harbour (0.431 m-1 ±0.091) mainly because of high attenuation rates
(turbidity) at the Don River outflow site. Despite a slightly higher attenuation rate in the inner
harbour, at all but the Don River outflow station the predicted euphotic zone was deeper than
the station depth, allowing for photosynthesis to occur throughout the full water column. The
euphotic zone also reached the bottom at the near and mid-shore stations to the west and east
of Toronto Harbour where light attenuation was measured. At the deepest station measured
(71m), the 1% euphotic zone reached to 20.5m or 29% of the water column.
26
Seasonal 2013
Light attenuation rates at LO8 increased from a low of 0.181 m-1 in June to a high of 0.286 m-1 in
September. Average attenuation was higher at LO8 compared to LO9 (Table 3.2). At LO9 light
attenuation was higher in June than in August. The euphotic zone (to 1% incidental light)
reached to the bottom (14m) at LO8 on all dates, whereas at LO9 Zeu1% reached to 20 and
20.4m. LO9 is 59m deep and in late summer and early fall the full epilimnion was in the euphotic
zone due to a deep mixed layer.
Water Chemistry and extracted chlorophyll
September 2013
As expected given the light attenuation rates, particulate organic nitrogen (PON), particulate
organic carbon (POC) and total phosphorus were higher in the inner harbour than in the east or
west (Table 3.2). The level of Kjeldhal nitrogen (organic + inorganic Ammonium) was also
higher here. Ammonia (NH3) is the preferred form of Nitrogen selected by autotrophs (Neel
1979) and was lowest in the inner harbour. Not surprisingly acetone extracted Chlorophyll a was
higher in the inner harbour (5.19 ±1.6 µg L-1) than the west (2.917 ±0.5 µg L-1) and both were
higher than the east (1.82 ±0.2 µg L-1) (Table 3.2).Some of the lowest densities of zooplankton
were found in the inner harbour while higher densities were seen in the east (see Section 1.2:
Zooplankton, and Section 1.1: Towed survey).
Dissolved organic Carbon (DOC) and soluble reactive phosphorus (SRP) were highest in the
east and slightly higher in the inner harbour compared to the western station region. This is
interpreted as being caused by outflow from one of Toronto’s major sewage treatment plants at
Ashbridges Bay. Higher DOC and SRP are generally associated with higher bioactivity in a
region.
Seasonal 2013
Calcium, sodium and dissolved inorganic carbon were stable through the season and similar at
the mid-shore (LO8, 14m) and offshore (LO9, 59m) stations (Table 3.2). There was a similar
seasonal trend seen at LO8 and LO9 for silica, SRP and nitrate plus nitrite. They were found to
be higher in June and October than in August and September. The opposite trend was seen in
DOC. Winter et al. (2011) reported a similar seasonal trend in NO2 +NO3 and silicate in Lake
Ontario waters collected at the water intake pipes in the Toronto Area.
These patterns are indicative of higher algal activity in the summer taking up the silica, SRP and
inorganic nitrogen and producing organic carbons. Chlorophyll a, which is indicative of standing
crop biomass, not production, only partially reflects this trend in our 2013 sampling, and showed
slightly higher chlorophyll in summer (August 1.59 ± 0.12 µg L-1, Sep 2.62 ± 0.68 µg L-1)
compared to spring (1.36 ± 0.26 µg L-1). Fall chlorophyll a values were much lower than earlier
in the season (0.335 ± 0.08 µg L-1).
TP and NH3 showed irregular patterns and there was a slight downward trend in Kjedal nitrogen
over the season.
FluoroProbe Chlorophyll and Pigment Groups
September 2013
The FluoroProbe measures fluorescence in the water column associated with algal pigment
groups and converts it to chlorophyll a as a standard measure. The average whole water
column (surface to bottom) chlorophyll a in the Toronto Harbour was 2.6 µg L-1 which is about
double the average for the few main lake stations sampled (1.3 µg L-1). The pigment groups are
associated with traditional taxonomic groups and give a version of the phytoplankton
27
composition. When comparing whole water column average pigment groups the main pigment
in the lake was the brown pigment (average 65%) which is associated with the Diatoms (Fig.
3.4). The inner Toronto Harbour also had a much higher proportion of green pigments (32%)
compared with stations outside the harbour (9%). Green pigments are associated mainly with
Chlorophyta but also occur in other algal groups.
Sub-surface maxima in total chlorophyll a were seen almost exclusively at the deep offshore
stations. These layers are shown in Fig. 3.5 and they coincide nicely with the large temperature
transitional layers shown in Fig. 3.2.
August 2010
Whole water column chlorophyll a averaged 3.1 µg L-1 at the Toronto Harbour stations and 1.3
µg L-1 at the main lake stations. As in the September 2013 survey, brown pigment was the
predominant contributor in the lake as measured by FluoroProbe contributing on average 47%
to total chlorophyll a. As in the 2013 survey, green pigments were more dominant in the inner
Toronto Harbour (48%) compared to the lake overall (27%).
Biological Parameters: Phytoplankton Biomass and Composition
September 2013
Phytoplankton biomass was low overall, ranging from 0.294 g m-3 at the nearshore Ashbridges
Bay station (an upwelling station) to 1.38 g m-3 at the western gap (Table 3.3, Fig. 3.6). These
values are considered ultra-oligotrophic on the scale devised by Munawar and Munawar (1982)
with the exception of the western gap station which is oligotrophic. Biomass was mainly
Cryptophyceae (8-64%) or Diatomeae (4-75%) with the exception of a large amount of
Dinophyceae at 2 stations (western gap =79% Peridinium sp. and mid depth Ashbridges Bay
Transect 49% Ceratium hirundinella Dujardin; Fig. 3.6). Chrysochromulina parva Lackey was
found at all 9 stations and often contributed over 5% of the biomass at the station (Table 3.3).
Cryptomonas erosa Ehrenberg contributed from 6-57% of total biomass at 7 of 9 stations while
Rhodomonas minuta nannoplanctica Skuja contributed from a minimum of 1.8% to over 24% at
all stations sampled. There were a variety of Diatom taxa identified with no one taxa present at
all stations. Cocconeis pediculus Ehrenberg contributed 3 to 30% at the 4 stations where it was
found, and Synedra filiformis Grunow and Cyclotella comensis Grunow were found at most
stations, often contributing over 1% of the total biomass.
Species richness was highest in the inner harbour and Humber Bay STP outflow station and
was lowest at the nearshore Ashbridges Bay station (Table 3.4). Richness in the inner harbour
averaged 36.6 ± 1.7 taxa (n=3), while the outer harbour shallow stations averaged 28.75 ± 3.5
taxa (n=4) and lake wide Ontario nearshore stations averaged 27.72 ± 2.61 taxa (n=11, August
2013 survey, Munawar unpublished data). Shannon diversity (Magurran 1988) was lower in the
inner harbour (1.89 ± 0.52; n=3) compared to the outer harbour shallow stations (2.15 ± 0.03;
n=4). The inner harbor values were also low compared to lake wide Ontario nearshore samples
taken in August 2013 (2.28 ± 0.11 (n=11); Munawar unpublished data) but not statistically
different. Alpha algal biomass (Magurran 1988) showed similar patterns to species richness and
Shannon diversity (Table 3. 4).
The Palmer water quality index scores (Palmer 1969, Table 3.4) were low indicating little
organic pollution at all stations, but had the highest scores in the eastern and western gaps.
These stations were also in areas where there was a lot of temperature layering and these shifts
in stability would have collected organic detritus (Fig. 3.2).
28
The majority of taxa identified in the Toronto area were undefined using the saprobien index
Kolkwitz and Marsson (1909) as this index is mainly used for periphyton and not phytoplankton.
None of the taxa identified were saprophobic (tolerating pristine conditions only) or saprophilic
(usually in polluted waters). Stations in nearshore Ashbridges Bay, mid shore Humber Bay, Don
Mouth and Eastern Gap each had a single taxon (Nitzschia palea) belonging to SI-S2, which
indicates preference for living in areas with high levels of pollution and/or considerable organic
material present. Five stations (inner harbour and nearshore Humber Bay) had taxa tolerant of
pollution but not of high DO content (Cyclotella meneghiniana, Cyclotella atomus and Cyclotella
silesiaca). Most ‘categorized’ biomass was found to be oligosaprobic (S5) or mesosaprobic beta
(S4) which by definition prefer highly oxygenated aquatic environments with moderate or little
organic material. This is consistent with well mixed and oligotrophic Lake Ontario waters.
Most taxa were not named in the nitrogen uptake metabolism scale of Van Dam et al. (1994,
2002) and of those listed most are nitrogen autotrophs requiring dissolved inorganic nitrogen for
growth. There was one facultative nitrogen-heterotrophic taxon (Cyclotella meneghiniana), that
needed the periodically elevated concentrations of organically bound nitrogen found at the
Humber nearshore, Don Mouth and Eastern Gap stations. Humber Bay nearshore was the only
area with an obligate nitrogen-heterotrophic taxon (Nitzschia acicularis). This taxon requires
continuously elevated concentrations of organically bound nitrogen, in this case likely provided
by the outflow of the Humber STP.
Biological Parameters: Size Fractionated Primary Productivity
September 2013
Total productivity was higher in the inner harbour (average =11.95 ± 5.0 mg C m -3 hr-1) than in
the west (average =4.4 ± 0.9 mg C m-3 hr-1) and east (average =3.3 ± 1.3 mg C m-3 hr-1). This is
mainly due to the influence of the Don River inflow station which had a total productivity of 26.8
mg C m-3 hr-1 (Fig. 3.7). Excluding the Don inflow, the inner harbour stations averaged 6.9 ± 0.7
mg C m-3 hr-1, still higher than the outer harbour stations. At all stations nanoplankton (2-20 µm
size) contributed the most to total productivity (47-55%) and the netplankton (greater than 20
µm) contributed the least (4-8.5%) to total productivity.
Seasonal 2013
Productivity was measured at LO8 and LO9 in June, September and October 2013 (Fig. 3.8).
Total productivity averaged about the same but variability was much greater at the shallower
station over the season (average 2.6 ± 1.42 mg C m-3 hr-1 at LO8 and 2.66 ± 0.34 mg C m-3 hr-1
at LO9). Variability is known to be great in the nearshore zone as it is more influenced by runoff
from precipitation events, air temperatures and onshore offshore circulation. As in the
September cruise, netplankton contributed the least to total productivity (3-30%) while the
nanoplankton (39-55%) and picoplankton (26-55%) contributed substantially more.
Biological Parameters: Microbial Loop Biomass
September 2013
The biomass of microbial loop components (APP, HNF and bacteria) during the September
2013 survey are shown in Fig. 3.9. Total biomass ranged from a low of 203 mg m-3 at the Don
River mouth (with very low APP and relatively high HNF indicating an impaired station) to a high
of 770 mg m-3 at the Western Gap where high HNF biomass accounted for the increase. This
was the biomass of phytoplankton in the Harbour at this time (200-1380 mg m-3) and to biomass
across the lake in late August 2013 (225-1177 mg m-3 Munawar unpublished data). As expected
for Great Lakes samples, bacteria were the largest component of the biomass with between 4480% of the total but this was a higher proportion than found in the lakewide survey. APP
contributed between 18-33% of the biomass and HNF were more variable with 0-36% of the
total.
29
Seasonal 2013
Microbial loop biomass was highly variable when measured at the Humber Bay transect stations
in June, August, September and October. Total average biomass ranged from a low of 144 mg
m-3 in September during the Toronto Harbour survey to a high of 309 mg m-3 during the August
survey. Average biomass by station was lowest at the nearshore (170 mg m-3) and highest in
the offshore (298 mg m-3). There is so much variability it is hard to see trends although bacteria
did increase over the season at the 2 deepest stations (Fig. 3.10).
Biological Parameters: Bacterial growth rates
September 2013
The potential growth rate determined for bacteria was much lower than the growth rate of the
phytoplankton but showed a similar trend with much higher rates in the inner harbour (3.08 ±
1.01 mg C m-3 hr-1) compared to the west (0.75 ± 0.36 1.01 mg C m-3 hr-1) and east (0.08 ± 0.05
mg C m-3 hr-1). The highest rate was found in the western gap (5.93 mg C m-3 hr-1) which was
more than 7 times the average in the west and 65 times higher than the average in the east
(Fig. 3.7). The next highest rate was found at the eastern gap which may be explained by the
higher number of temperature transition zones found in the gaps. These layers could trap
plankton cells and other detritus on which bacteria would feed. Following this line of thought the
offshore of Ashbridges Bay was higher than the nearshore stations and it had the most layering
seen in the sampled water zone. Unfortunately, temperature profiles collected at water
collection points in Humber Bay show decreased bacterial production with increased layering,
but it is more likely the increase growth in the nearshore is related to proximity to the Humber
Bay STP.
Seasonal 2013
Rates of bacterial growth were much lower than that of the algae averaging 0.33 ± 0.26 mg C m3
hr-1 at LO8 and 0.04 ± 0.01 mg C m-3 hr-1 at LO9 (Fig. 3.8). As with the algae the nearshore
station was much more variable than the offshore mainly due to high rates in September as was
also seen in the algal productivity.
Summary and Conclusions
This region of Lake Ontario is a highly dynamic physical system (internal oscillations, upwelling)
which affects the response of phytoplankton to other stressors such as nutrients and toxins
(Haffner et al. 1984a). There were several intensive studies of phytoplankton in Toronto Harbour
and area (Nalewajko 1966; Haffner et al. 1982 and 1984b; Munawar et al. 1993, 2003) and
these historical studies gives some evidence for an impaired phytoplankton community in the
inner harbour. These lines of evidence included:
•
•
Total biomass consistently > 3 g m-3 (i.e. eutrophic)( Haffner et al. 1984b, Munawar et al.
2003, Munawar 1988 unpublished data)
Euglenophyta and other pollution-tolerant flagellated forms dominating biomass at times
(sewage outflows, Haffner et al. 1982, 1984b; Munawar et al. 1989a; Munawar et al.
2003, Munawar 1988 unpublished data)
The survey undertaken by DFO in September 2013 was influenced by the highly variable
physical structure in the lake as it was undertaken during one of the largest upwelling events
seen in 2012 and 2013 (B. Hlevca, University of Toronto, personal communication, 2015) and
this confounds the analysis. A storm also came through between the second and third day’s
sampling further affecting the results.
30
The shallow, enclosed harbour is distinct from the main lake even with its very high flushing
rate. In September 2013, phytoplankton biomass was typically < 1 g m-3 in the ultra-oligotrophic
range and was higher in the inner harbour as was TP. Phytoplankton composition was highly
variable between stations although there were a preponderance of flagellated forms (79% in
inner harbour) which are able to move up and down in the water column and have the ability to
deal with the complex physical structure in the area.
Primary productivity was generally low (< 5 mg C m-3 h-1) and comparable to the open lake,
except at the Don River mouth where it was quite high. Productivity of algae and bacteria were
higher in the inner harbour compared to other stations. Dissolved organic carbon of algal origin
is usually considered to be of high quality for bacterial use, as suggested by the pattern of
increased bacterial production with increased primary production (Cole et al. 1988), even
without an increase in nutrient in the higher production areas.
Ammonia levels were lower in the inner harbour while there was no trend in NO3 between
regions. As ammonia is selected by autotrophs ahead of nitrate (Neel 1979) the increase in
phytoplankton biomass and productivity in the harbour can help to explain the lower levels found
there.
It was expected that the shallow inner harbour with sediment laden inflow from the Don River
and higher productivity than the main lake would result in higher light attenuation rates than
outside the harbour, but the upwelling event caused the eastern measures to be lower than
expected given the inflow from the STP in Ashbridges Bay. The upwelling was not as evident in
Humber Bay as it was in Ashbridges Bay, probably due to the bathymetry of the area.
The September 2013 survey provides only a snapshot of current conditions in Toronto Harbour
and area. Given the scarcity of recent data, comprehensive spatial and temporal assessment is
needed to more fully understand the current status of phytoplankton in Toronto Harbour and
area.
31
Acknowledgements
All of the authors would like to acknowledge the contributions of a number of individuals who
gave support or improved the manuscript. The fieldwork for this study required assistance well
beyond the authors, involving flexible scheduling and patience of several technicians: Jocelyn
Kydd, Dallas Linley, Robert Bonnell, Ashley Bedford, Jason Read and Robin Roson. The
primary production and microbial loop findings were carried out in the lab of Mohi Munawar with
the support of Mark Fitzpatrick. Data on fish community composition was supplied by Christine
Boston, Kathy Leisti (DFO, GLLFAS) and Jim Hoyle (OMNRF). We also thank the captain and
crew of the CCGS Kelso in carrying out the 2010 nearshore survey. The support and input of
Marten Koops has been consistent throughout the planning and implementation stages. Other
agencies were also vital to the completion of this project. We appreciate the input of Rod
Anderton and the City of Toronto for historic chemistry data and station locations which were
vital to the sampling planning at a location we had not worked in previously. Appreciation goes
to Nadine Benoit (OMOECC) for supplying details on the Index Sampling Station program.
Thanks go to Toronto Region Conservation Authority for support in securing slips at Outer
Harbour Marina and staff at PortsToronto for obliging our need for flexible scheduling. Funding
for the study was secured through Environment Canada under the Great Lakes Action Plan
upon request from the Toronto Region RAP and research base funding at DFO GLLFAS.
32
References
Blukacz, E.A., Shuter, B.J., and Sprules, W.G. 2009. Towards understanding the relationship
between wind conditions and plankton patchiness. Limnol. Oceanog. 54:1530-1540.
Bowen K.L., and Johannsson, O.E. 2011. Changes in zooplankton biomass in the Bay of Quinte
with the arrival of the mussels Dreissena polymorpha and D. rostiformis bugensis, and the
predatory cladoceran Cercopagis pengoi: 1975-2008. Aquat. Ecosys. Health Manag. 14:4455
Brooks, J.L., and Dodson, S.I. 1965. Predation, Body Size, and Composition of Plankton.
Science 150: 28-35.
Cole J.J., Findlay S., and Pace M.L. 1988. Bacterial production in fresh and saltwater
ecosystems: a cross- system overview. Mar. Ecol. Prog. Ser. 43:1-10.
Cooley, J.M., Moore, J.E., and Geiling, W.T. 1986. Population dynamics, biomass, and
production of the macrozooplankton in the Bay of Quinte during changes in phosphorus
loadings. In Project Quinte: point source phosphorus control and ecosystem response in the
Bay of Quinte, Lake Ontario. Edited by C.K. Minns, D.A. Hurley, and K.H. Nicholls, pp. 166–
176. Can. Spec. Publ. Fish. Aquat. Sci. No. 86.
Crumpton, W.G. 1987. A simple and reliable method for making permanent mounts of
phytoplankton for light and fluorescence microscopy. Limnol. Oceanogr. 32:1154-1159.
CSMI 2013 Coordinating Committee, 2014. Lake Ontario 2013 CSMI Progress Report. 5 p.
http://www.dec.ny.gov/docs/water_pdf/csmi2013progrpt2.pdf
Currie, W.J.S., and Roff, J.C. 2006. Plankton are not passive tracers: Plankton in a turbulent
environment. Journal of Geophysical Research-Oceans 111(C5).
Dermott, R., Johannsson, O., Munawar, M., Bonnell, R., Bowen, K., Burley, M., Fitzpatrick, M.,
Gerlofsma, J., and Niblock, H. 2007. Assessment of lower food web in Hamilton Harbour,
Lake Ontario, 2002 - 2004. Can. Tech. Rep. Fish. Aquat. Sci. 2729:120 p.
Dobiesz, N.E., and Lester, N.P. 2009. Changes in mid-summer water temperature and clarity
across the Great Lakes between 1968 and 2002. J. Great Lakes Res. 35:371-384.
Environment Canada and Ontario Ministry of the Environment. 2011. Toronto and Region Area
of Concern Status of Beneficial Use Impairments September 2010. Queen’s Printer for
Ontario, Toronto, ON. 8 p.
Finlay, K., Beisner, B.E., and Barnett, A.J.D. 2007. The use of the Laser Optical Plankton
Counter to measure zooplankton size, abundance, and biomass in small freshwater lakes.
Limnology and Oceanography-Methods 5:41-49.
Folt, C.L., and Burns, C.W. 1999. Biological drivers of zooplankton patchiness. Trends Ecol.
Evol. 14: 300-305.
Genin, A., Jaffe, J.S., Reef, R., Richter, C., and Franks, P.J.S. 2005. Swimming against the
flow: A mechanism of zooplankton aggregation. Science 308(5723):860-862.
Haffner, G.D., Poulton, D.J., and Kohli, B. 1982. Physical Processes and Eutrophication. Water
Res. Bull. 18:457-464.
Haffner, G. D., Yallop, M. L., Hebert, P. D. N., and Griffiths, M. 1984a. Ecological significance of
upwelling events in Lake Ontario. J. Great Lakes Res. 10:28-37
Haffner, G.D., Griffith, M., and Herbert, P.D.N. 1984b. Phytoplankton community structure and
distribution in the nearshore zone of Lake Ontario. Hydrobiologia 114:51-66.
Harris, R., Wiebe, P.H., Lenz, J., Skjoldal, H.R., and Huntley, M.E. 2000. ICES Zooplankton
Methodology Manual. Academic Press, New York.
Herman, A.W., Beanlands, B., and Phillips, E.F. 2004. The next generation of Optical Plankton
Counter: the Laser-OPC. J. Plankton Res. 26:1135-1145.
Herman, A.W., and Harvey, M. 2006. Application of normalized biomass size spectra to laser
optical plankton counter net intercomparisons of zooplankton distributions. J. Geophysical
Res. Oceans 111(C5).
33
Holeck, K.T., Watkins, J.M., Mills, E.L., Johannsson, O., Millard, S., Richardson V. and Bowen,
K. 2008. Spatial and long-term temporal assessment of Lake Ontario water clarity,
nutrients, chlorophyll a, and zooplankton. Aquatic Ecosystem Health & Management, 11:
377 — 391
Howell, E.T., Chomicki, K.M., and Kaltenecker, G. 2012. Patterns in water quality on Canadian
shores of Lake Ontario: correspondence with proximity to land and level of urbanization. J.
Great Lakes Res. 38:32–46.
Hoyle, J. 2013. Examining the Toronto Waterfront Fish Community in the Lake Ontario Context:
NSCIN Trap Netting. Presentation to Toronto FMP Workshop April 10 2013
http://aquatichabitat.ca/wp/wp-content/uploads/2013/03/Fish-Community-Workshop-Part3.pdf
Johannsson, O. E. 2003. A history of changes in zooplankton community structure and function
in Lake Ontario: responses to whole-lake remediation and exotic invasions. In State of Lake
Ontario: Past, Present and Future, pp. 221–256. Ed. M. Munawar, Ecovision World
Monograph Series, Aquatic Ecosystem Health and Management Society, Burlington, ON.
Johannsson, O.E., and O'Gorman, R. 1991. Roles of predation, food, and temperature in
structuring the epilimnetic zooplankton populations in Lake Ontario, 1981–1986,
Transactions of the American Fisheries Society, 120:193-208
Jorgensen, N.O.G. 1992. Incorporation of 3H-leucine and 3H-valine into protein of freshwater
bacteria: Uptake kinetics and intracellular isotope dilution. Applied Envi. Microbiology
58:3638 - 3646.
Kolkwitz, R., and Marsson, M. 1909. Ökologie der tierischen Saprobien. Beiträge zur Lehre von
der biologischen Gewässerbeurteilung. Int. Revue ges. Hydrobiol. Hydrogr. 2:126-152.
doi: 10.1002/iroh.19090020108.
Lee, A. H. 1972. Regional characteristics of the thermal properties of Lake Ontario. In Proc.
15th Conf. Great Lakes Res., pp. 625-634. Internat. Assoc. Great Lakes Res.
Liebig, J.R., and Vanderploeg, H.A. 2008. Selecting Optical Plankton Counter Size Bins to
Optimize Zooplankton Information in Great Lakes Studies GLERL-143.
Lind, O.T., and Campbell, R.S. 1969. Comments on the use of liquid scintillation for routine
determination of C-14 activity in production studies. Limnol. Oceanogr. 14:787-789.
Lovejoy, S., Currie, W.J.S., Tessier, Y., Claereboudt, M.R., Bourget, E., Roff, J.C., and
Schertzer, D. 2001. Universal multifractals and ocean patchiness: phytoplankton, physical
fields and coastal heterogeneity. J. Plankton Res. 23:117-141.
Mackas, D.L., Denman, K.L., and Abbott, M.R. 1985. Plankton Patchiness - Biology in the
Physical Vernacular. Bull. Marine Sci. 37:652-674.
Magurran, A.E. 1988.Ecological Diversity and Its Measurement. Princeton University Press,
Princeton, New Jersey.
Makarewicz, J.C., and Lewis, T.W. 2015. Long-term changes in Lake Ontario rotifer abundance
and composition: A response to Cercopagis predation? J. Great Lakes Res. 41:192–199.
Makarewicz, J.C., and Likens, G.E. 1979. Structure and function of the zooplankton community
of Mirror Lake, New Hampshire. Ecol. Monogr. 49:109–127.
Mills, E.L., Green, D.M., and Schiavone, A. 1987. Use of zooplankton size to assess the
community structure of fish populations in freshwater lakes. N. Am. J. Fish. Manage. 7:369–
378.
Milne, S. 2014. 2013 Western Lake Ontario CSMI Hydroacoustic Survey Report. Prepared for
Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada.
108 p.
Miners, K.C., Chiocchio, F., and Rao, Y.R., Pal, B., Murthy, C.R. 2002. Physical processes in
Western Lake Ontario for sustainable water use National Water Research Institute Scientific
Report No.02-176 p. 162.
34
Montagnes, D.J.S., and Lynn, D.H. 1993. A quantitative protargol stain (QPS) for ciliates and
other protists. In: Kemp, P.F., Sherr, B.F., Sherr, E.B., and Cole, E.J. (Eds), Handbook of
methods in aquatic microbial ecology. Lewis Publishers, Boca Raton, FL.
Morris, T.J., and Sprules, W.G. 2003. A comparison of egg ratio method and optical plankton
counter methodologies for estimating zooplankton production Spatial and temporal trends in
Lake Ontario 1991 – 1997. In State of Lake Ontario: Past, Present and Future, pp.289-304
Edited by M. Munawar, Ecovision World Monograph Series, Aquatic Ecosystem Health and
Management Society, Burlington, ON.
Munawar, M., and Munawar, I.F. 1982. Phycological studies in Lakes Ontario, Erie, Huron and
Superior. Invited Contribution. Can. J. Bot. 60:1837-1858.
Munawar, M., W.P. Norwood, McCarthy, L.H., and Mayfield, C.I. 1989a. In situ bioassessment
of dredging and disposal activities in a contaminated ecosystem: Toronto Harbour. In: M.
Munawar, G. Dixon, C.I. Mayfield, T. Reynoldson, M.H. Sadar (Eds.), Environmental
Bioassay Techniques and Their Application. Hydrobiologia 188/189:601-618.
Munawar, M., Gregor, D., Daniels, S.A., and Norwood, W.P. 1989b. A sensitive screening
bioassay technique for the toxicological assessment of small quantities of contaminated
bottom or suspended sediments. Hydrobiologia 176/177:497-507.
Munawar, M., Munawar, I.F., Mayfield, C.I., and McCarthy, L. 1989c. Probing ecosystems
health: A multi- In disciplinary and multi-trophic assay strategy. In: M. Munawar, G. Dixon,
C.I. Mayfield, T. Reynoldson, M.H. Sadar (Eds.), Environmental Bioassay Techniques and
their Application. Dev. Hydrobiology 54:93-116. Kluwer Academic Publishers, Dordrecht.
Reprinted from Hydrobiologia 188/189.
Munawar, M., Munawar, I.F., McCarthy, L., Page, and W., Gilron, G. 1993. Assessing the
impact of sewage effluent on the ecosystem health of the Toronto Waterfront (Ashbridges
Bay), Lake Ontario. J. Aquat. Ecosyst. Health. 2:287-315.
Munawar, M., Legner, M., and Munawar, I.F. 2003. Assessing the microbial food web of Lake
Ontario. In: M. Munawar (Ed.), State of Lake Ontario, Past Present and Future, pp. 135-170.
Ecovision World Monograph Series. Aquatic Ecosystem Health and Management Society,
Burlington, ON.
Munawar, M., Fitzpatrick, M., Munawar, I. F., Niblock, H., and Kane, D. 2012. Assessing
ecosystem health impairments in the Laurentian Great Lakes: A battery of ecological
indicators strategy in the Bay of Quinte. Aquat. Ecosyst. Health Mgmt. 15:430–441.
Munawar, M., Munawar, I.F., and Fitzpatrick, M. 2013. Microbial foodweb comparison of the
Laurentian Great Lakes during the summers of 2001–2004. Aquat. Ecosyst. Health Mgmt.
16:267-278.
Nalewajko, C. 1966. Composition of Phytoplankton in Surface Waters of Lake Ontario J. Fish.
Res. Brd. Canada 23:1715-1725.
Neel, J.K. 1979. Watershed and point source enrichment and lake trophic state index. Corvallis
Environmental Research Laboratory, University of North Dakota. Dept. of Biology
Environmental Protection Agency, Office of Research and Development, Corvallis
Environmental Research Laboratory, 102 pages.
Palmer, C.M. 1969. A composite rating of algae tolerating organic pollution. J. Phytocol. 5:7882.
Patalas, K. 1969. Composition and horizontal distribution of crustacean plankton in Lake
Ontario. J. Fish. Res. Board Can. 26:2135–1462.
Pichlová-Ptáčníková, R., and Vanderploeg, H.A. 2009. The invasive cladoceran Cercopagis
pengoi is a generalist predator capable of feeding on a variety of prey species of different
sizes and escape abilities. Archiv für Hydrobiologie Vol. 173/4:267–279
Porter, K.G., and Feig, Y.S. 1980. The use of Dapi for identifying and counting aquatic
microflora. Limnol. Oceanogr. 25:943-948.
35
Rand, P.S., Stewart, D.J., Lantry, B.F., Rudstam, L.G., Johannsson, O.E., Goyke, A.P., Brandt,
S.B., O’Gorman, R., and Eck, G.W. 1995. Effect of lake-wide planktivory by the pelagic
community in Lakes Michigan and Ontario. Can. J. Fish. Aquat. Sci. 52:1546–1563
Rudstam, L.G., Holeck, K.T., Bowen, K.L., Watkins, J.M., Weidel, B.C., and Luckey, F.J. 2015.
Lake Ontario zooplankton in 2003 and 2008: Community changes and vertical redistribution.
Aquat. Ecosyst. Health Mgmt. 18:43-62
Speirs, D.C., and Gurney, W.S.C. 2001. Population persistence in rivers and estuaries. Ecology
82(5): 1219-1237.
Sprules, W.G. 2008. Ecological change in Great Lakes communities – a matter of perspective.
Can. J. Fish Aquat. Sci. 65:1-9.
Sprules, W.G., and Goyke, A.P. 1994. Size-Based Struction and Production in the Pelagia of
Lakes Ontario and Michigan. Can. J. Fish Aquat. Sci. 51:2603-2611.
Sprules, W.G., Jin, E.H., Herman, A.W., and Stockwell, J.D. 1998. Calibration of an optical
plankton counter for use in fresh water. Limnol. Oceanogr. 43:726-733.
Stemberger, R. S. 1986. The effects of food deprivation, prey density and volume on clearance
rates and ingestion rates of Diacyclops thomasi. J. Plankton Res. 8:243-251.
Strickland, J.D.H., and Parsons, T.R. 1968. A Practical Handbook of Seawater Analysis.
Fisheries Research Board of Canada, Bulletin 167:71–75.
Utermöhl, H. 1958. Zur vervolkommnung der quantitativen phytoplankton-methodik. (The
improvement of quantitative phytoplankton methodology. In German.) Mitt. Internat. Verein.
Limnol. 9:1-38.
Van Dam, H., Mertens, A., and Sinkeldam, J. 1994. A coded checklist and ecological indicator
values of freshwater diatoms from the Netherlands: Netherlands J. of Aquatic Ecol. 28:117133.
Van Dam, H. 2002. Additions to a coded checklist and ecological indicator values of freshwater
diatoms from the Netherlands: digital communication, 2/21/2002.
Vanderploeg, H.A., and Roman, M.R. 2006. Introduction to special section on Analysis of
Zooplankton Distributions Using the Optical Plankton Counter. J. Geophysical Res. Oceans
111(C5).
Vollenweider, R. A., Munawar, M., and Stadelmann, P. 1974. A comparative review of
phytoplankton and primary production in the Laurentian Great Lakes. J. Fish. Res. Bd. Can.
31:739-762.
Walsh, M.G., Weidel, B.C., and Connerton, M.J. 2014. Status of Alewife in the U.S. Waters of
Lake Ontario, 2013. In 2013 NYSDEC Annual Report, Bureau of Fisheries Lake Ontario Unit
and St. Lawrence River Unit to Great Lakes Fishery Commission’s Lake Ontario Committee.
Watkins, J., Rudstam, L.G., and Holeck, K. 2011. Length-weight regressions for zooplankton
biomass calculations – A review and a suggestion for standard equations. eCommons
Cornell. http://ecommons.library.cornell.edu/handle/1813/24566.
Watson, N. H. F., and Carpenter, G. F. 1974. Seasonal abundance of crustacean zooplankton
and net plankton biomass of lakes Huron, Erie, and Ontario. J. Fish. Res. Board Can.
31:309-317.
Winter, J.G., Howell, E.T., and Nakamoto, L.K. 2011. Trends in nutrients, phytoplankton, and
chloride in nearshore waters of Lake Ontario: Synchrony and relationships with physical
conditions. J. Great Lakes Res. 38:124-132.
Yan, N.D. and Pawson, T.W., 1997. Changes in the crustacean zooplankton community of Harp
Lake, Canada, following invasion by Bythotrephes cederstroemi. Freshw. Biol 37: 409-425.
Yurista, P.M., Kelly, J.R., Cotter, A.M., Miller, S.E., and Van Alstine, J.D. 2015. Green Bay:
Spatial variation in water quality, and landscape correlations. J. Great Lakes Res. 41:560572.
Yurista, P.M., Kelly, J.R., Miller, S., and Van Alstine, J. 2012. Lake Ontario: Nearshore
conditions and variability in water quality parameters. J. Great Lakes Res. 38:133-145.
36
Tables
Table 1.1: Corresponding taxonomic groupings of zooplankton based on Equivalent Spherical
Diameter (ESD) measures from the LOPC.
ESD bin
range [µm]
75-150
151-300
301-405
406-600
600+
Likely zooplankton composition
Major Group
Larger Dreissenid veligers
Some large protists (e.g. Ceratium)
Larger rotifers (Keratella, Synchaeta)
Chydorus
Harpactacoid copepods
Larger copepod Nauplii
Bosmina sp.
Eubosmina sp.
Alona sp.
Cyclopoid copepodids (juvenile)
Ceriodaphnia sp.
Polyphemus sp.
Holopedium sp.
Diacyclops thomasi (adult)
Calanoid copepodids
Daphnia sp.
Diaphanosoma
Leoptodiaptomis sp.
Mollusca
Protista
Rotifera
Cladocera
Copepoda
…
Cladocera
…
…
Copepoda
Cladocera
…
…
Copepoda
…
Cladocera
…
Copepoda
…
Predatory Cladocera
…
…
Copepoda
Cercopagis
Bythotrephes
Leptodora
Limnocalanus
37
Table 2.1: Sampling information for stations in the Toronto area during the August 2010
western Lake Ontario nearshore survey. Mean values and standard errors are given for surface
temperature, secchi disk depth and turbidity (in bold). Chlorophyll a was only measured at three
stations.
Station
Sounding Chlor a
(m)
ug.L-1
Long (W)
Surface
Temp C
Secchi
(m)
Turbidity
(NTU)
Zoopl.
Rotifers
analyzed analyzed
Date
Lat. (N)
K22
09-Aug-10
43°37.6408
79°28.0034
7.4
-
16.9
2.0
2.1
Yes
No
2047
12-Aug-10
43°37.5677
79°26.9036
13.8
2.8
21.7
4.0
0.8
Yes
Yes
No
Humber
19.3 ± 2.4 3.0 ± 1.0
Inner Harbour
20.3 ± 0.2 2.9 ± 0.4
1.4 ± 0.7
1.5 ± 0.5
TH1
12-Aug-10
43°38.0693
79°23.4252
6.5
-
20.7
4.0
0.9
Yes
726
12-Aug-10
43°38.0340
79°22.8550
7.7
-
20.3
3.5
1.1
Yes
No
1364
725
TH2
11-Aug-10
12-Aug-10
11-Aug-10
43°38.1061
43°38.4572
43°37.9297
79°22.2479
79°21.7926
79°20.4435
8.4
9.7
11.3
7.0
5.3
19.5
20.6
20.5
1.5
2.6
3.0
3.1
2.1
0.5
Yes
Yes
Yes
Yes
No
No
11-Aug-10
11-Aug-10
43°39.0804
43°38.1770
79°18.7469
79°18.5072
6.1
13.8
-
19.8 ± 0.6
19.2
20.4
6.0
6.0
0.5 ± 0.1
0.5
0.6
Yes
Yes
Yes
No
12-Aug-10
12-Aug-10
11-Aug-10
11-Aug-10
11-Aug-10
43°36.4650
43°35.9738
43°36.6457
43°36.2424
43°36.9223
79°26.0350
79°26.2198
79°21.8215
79°21.8379
79°18.2756
27.2
39.3
8.8
36.1
69.7
-
20.8 ± 0.4 5.8 ± 1.1
20.9
10.0
21.9
6.0
19.5
4.0
21.2
4.0
20.7
5.0
0.7 ± 0.0
0.8
0.6
0.6
0.7
0.6
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
Ashbridges
431
909
Offshore
1323
K23
TH3
TH4
TH5
38
Table 2.2. Summary of 2013 sampling depths for zooplankton net hauls and epilimnetic rotifers.
Samples shaded in grey were collected but not counted; the rest were analyzed. The individual
depth stratum samples (Epi=epilimion, Meta = metalimnion and Hypo = hypolimnion) were
collected using a 64 µm net, whereas the total nets (T) were collected using a 153 µm net.
“E+M” indicates total water column samples were made by pooling the 64 µm epilimnetic and
metalimnetic nets and counted. The “-“ symbol indicates this net was not collected. Study area
abbreviations are explained in Figure 2.6.
Sounding
Date
Station
Region Depth (m)
Total
Zoopl. Strata Depths (m)
Net
Epi
Rotifer
Meta
Hypo
Depth (m)
0-8
0-5
0-4
0-6
September 2013 AOC Survey
11-Sep
11-Sep
11-Sep
09-Sep
IH1
IH
9.6
E+M
0-3.5
3.5-8
-
1364
IH
8.4
E+M
0-3.5
3.5-7.5
-
L12
IH
9.0
E+M
0-3
3-8
-
IH13
IH
8.6
E+M
0-3.5
3.5-8
-
09-Sep
09-Sep
11-Sep
09-Sep
11-Sep
09-Sep
HB3
NS
5.3
T
0-4.5
-
-
LO8
NS
15.4
T
0-5
5-14
-
0-4.5
0-5
ST1
NS
9.7
E+M
0-3
3-8
-
-
TH3
NS
8.6
T
0-4.5
4.5-7.5
-
-
OH1
NS
11.3
T
0-4
4-10
-
-
AB2
NS
8.7
T
0-7.5
-
-
0-7
09-Sep
09-Sep
09-Sep
09-Sep
3508
Off
20.6
T
0-4
4-19
-
-
LO9
Off
59.4
T
0-5.5
5.5-15
15-58
0-5
TH4
Off
44.0
T
-
-
-
-
AB3
Off
42.0
T
-
-
-
-
13-Sep
13-Sep
13-Sep
13-Sep
13-Sep
AB1
East
7.0
T
0-6.5
-
-
1325
East
17.5
T
0-12.5
12.5-16
-
1326
East
71.0
T
0-12
12-25
25-70
708
East
15.8
T
0-6
6-11
11-15
0-7
0-8
0-8
0-6
1329
East
29.0
T
0-5
5-15
15-29
-
2013 CSMI Surveys
12-Jun
LO8
NS
15
T
0-13
-
-
0-14
12-Jun
LO9
Off
60.8
T
0-25
25-35
35-59
0-20
24-Aug
LO8
NS
14.6
T
0-13
-
-
0-7
24-Aug
LO9
Off
60
T
0-6
6-10
10-58
0-6
21-Oct
LO8
NS
15
T
0-13
-
-
0-10
21-Oct
LO9
Off
60
T
0-10
39
10-14.5 14.5-57
0-10
Table 2.3: Number of zooplankton samples analyzed, mean total water column density and
biomass (including standard errors) for each of the areas sampled in August 2010, August 2012
and Sept. 2013. Study area abbreviations are explained in Figure 2.6. Percent composition by
biomass for the dominant zooplankton groups and taxa are also given.
Aug. 2010
HB
No. samples
total density (No.L-1)
IH
Aug. 2012
Off
Ash
IH
Sept. 2013
IH
NS
Off
East
2
5
5
2
2
4
6
4
5
9.7
57.3
56.5
52.4
25.6
12.1
9.7
37.4
103.5
37.6
14.0
8.2
49.4
3.8
2.4
3.0
9.9
40.5
Total biomass (mg.m )
18.2
65.5
105.8
42.9
42.7
8.3
6.3
41.5
74.3
SE of Biomass
10.4
5.5
14.4
34.6
5.1
2.1
1.7
11.8
33.9
SE of Density
-3
% Composition by biomass
Cladocera
69.8
67.9
69.6
67.6
91.2
62.0
56.7
27.9
39.8
Bosmina sp.
Cercopagis pengoi
1.2
2.2
11.3
1.1
1.5
0.2
3.8
2.7
8.8
2.0
28.7
1.1
29.0
3.3
10.5
1.4
16.0
0.8
Ceriodaphnia lacustris
0.0
0.9
0.6
0.0
2.2
3.5
2.9
0.2
0.1
Chydorus sphaericus
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Daphnia galeata
23.7
14.2
40.7
20.7
10.8
6.4
5.2
2.6
4.3
Daphnia retrocurva
12.6
37.2
23.4
20.3
25.2
16.9
8.1
10.1
15.0
Diaphanosoma sp.
0.0
0.2
0.0
0.0
0.3
0.5
0.0
0.0
0.0
Eubosmina sp.
0.9
1.1
0.7
4.9
16.9
2.8
3.4
1.3
1.8
3.2
19.8
0.2
0.8
0.9
1.2
10.8
3.0
24.6
0.2
0.5
0.1
2.4
1.2
1.0
0.7
1.2
0.6
6.0
5.6
0.4
0.0
0.0
2.6
1.4
0.5
0.7
0.0
2.8
0.9
0.4
1.5
0.0
3.0
1.5
0.4
1.1
0.0
2.4
1.4
0.1
0.9
0.0
18.1
7.3
5.2
5.6
0.0
26.3
12.8
4.6
8.9
0.0
61.3
23.7
4.9
32.7
0.0
42.4
12.2
9.0
21.1
0.0
10.1
2.4
0.5
1.5
0.6
0.3
9.5
4.8
0.2
3.9
1.0
0.1
1.4
0.4
0.2
2.7
1.4
1.3
5.7
0.5
0.2
3.4
1.9
0.1
8.3
1.4
0.3
Epischura lacustris
Leptodiaptomus sicilis
Limnocalanus macrurus
Sk istodiaptomus oregonensis
1.5
0.0
0.0
0.6
0.0
0.2
0.0
0.0
0.0
3.1
0.8
0.1
1.0
1.4
0.0
0.0
0.0
0.0
0.0
0.3
0.0
0.0
0.0
0.0
0.0
0.4
2.6
0.4
0.0
0.8
0.0
0.0
0.0
2.2
1.5
2.7
other / unknown diaptomids
5.1
0.4
0.5
0.4
0.5
0.0
1.7
0.6
0.2
14.0
28.0
18.2
25.6
4.9
17.2
11.2
7.5
9.5
Holopedium gibberum
Leptodora k indtii
Cyclopoids
copepodites
nauplii
Diacyclops thomasi
Mesocyclops edax
Calanoids
copepodites
nauplii
Veligers
40
Table 3.1: Station location and light attenuation information September 2013 survey. Some light
attenuation values are missing due to logger error or low light levels during sampling (night).
Location
Latitude (N)
Longitude
(W)
Station
Depth
(m)
Surface
Temperature
(°C)
Secchi
Depth
(m)
Light
Attenuation
rate (m-1)
WEST OF TORONTO
HARBOUR
3508
43° 34.363
HB3
43° 37.861
LO8
43° 37.40
LO9
43° 35.200
TH3
43°36.6457
TH4
43°36.2424
79° 30.95
79° 28.179
79° 27.2
79° 23.700
79°21.8215
79°21.8379
20.6
5.3
15.4
59.4
8.6
44
14
15.6
13.9
15.9
13.6
n/a
7
2
4.25
5.5
3
5
na
0.297
0.286
na
0.332
na
TORONTO HARBOUR
MOE1364
43° 38.106
L12
43° 38.611
IH1
43° 38.053
IH13
43° 38.189
L10
43° 38.226
ST1
43° 37.685
OH1
43° 37.560
TH1
43° 37.930
79° 22.248
79° 21.843
79° 23.728
79° 21.216
79° 22.948
79° 24.456
79° 20.912
79° 20.444
8.4
9
9.6
8.6
7.3
9.7
11.3
9
16.2
17
16.5
17
16.6
17.6
15.6
16
2.5
2
5
5
2.7
5
3.5
na
0.379
0.675
0.252
0.232
0.616
0.332
0.332
na
EAST OF TORONTO
HARBOUR
AB1
43° 39.489
AB2
43° 38.466
AB3
43° 37.401
1325
43° 39.013
1326
43° 38.185
708
43° 47.617
1329
43° 45.674
1330
43° 44.322
1328
43° 46.404
79° 17.730
79° 18.967
79° 18.028
79° 15.786
79° 14.964
79° 5.100
79° 5.837
79° 3.408
79° 6.787
7
8.7
42
17.5
71
15.8
29
65
12.5
10.7
11.1
n/a
12.2
13
14
13.3
15.5
13
5.5
7
8
4
5
na
na
na
na
0.229
0.208
na
0.227
0.224
0.198
na
na
na
41
Table 3.2: Water chemistry parameters (mean ± SE mg L-1 unless otherwise indicated) and light
attenuation from Toronto Harbour area 2013. LO8 and LO9 are monthly samples June-October
while the remaining represent a wider range of stations sampled in September 2013.
LO9
Seasonal
JuneOctober
4
West Outer
Harbour
Sep 9, 2013
n
Chl a
extracted
-1
(µg L )
TP-P-UF
LO8
Seasonal
JuneOctober
4
East Outer
Harbour
Sep 13,
2013
3
Spatial
Survey All
Stations
3
Inner
Harbour
Sep 11,
2013
4
1.533±0.643
1.422±0.341
2.917±0.49
5.19 ±1.570
1.82±0.168
3.497±0.761
0.113±0.094
0.014±0.003
0.023±0.003
0.035±0.008
0.020±0.001
0.027±0.004
SRP-P-F
0.003±0.001
0.002±0.000
0.002±0.001
0.003±0.001
0.008±0.002
0.004±0.001
NO3NO2-F
0.386±0.048
0.339±0.035
0.385±0.046
0.358±0.006
0.368±0.009
0.369±0.013
TKN-N-F
0.239±0.008
0.236±0.009
0.243±0.014
0.275±0.034
0.248±0.002
0.257±0.014
NH3-N-F
0.018±0.007
0.015±0.003
0.012±0.005
0.003±0.000
0.020±0.001
0.010±0.003
10
DIC
20.93±0.189
20.78±0.189
21.23±0.433
21.90±0.091
21.23±0.491
21.50±0.204
DOC
2.500±0.196
2.500±0.191
3.100±0.208
4.300±0.799
7.133±3.362
4.790±1.063
POC
0.401±0.125
0.291±0.059
0.375±0.017
0.650±0.115
0.267±0.036
0.453±0.070
PON
0.051±0.013
0.046±0.011
0.069±0.003
0.118±0.022
0.045±0.005
0.082±0.013
CA-F
34.15±0.357
34.18±0.466
34.73±0.769
36.83±0.330
35.07±0.088
35.67±0.394
NA-F
15.38±0.61
14.70±0.29
17.23±1.30
19.03±1.22
18.90±3.90
18.45±1.18
MG-F
8.893±0.094
8.905±0.063
9.063±0.081
8.970±0.031
8.867±0.027
8.967±0.035
SIO2-F
0.813±0.178
0.685±0.160
0.803±0.179
1.088±0.076
0.830±0.010
0.925±0.070
K-F
1.780±0.045
1.730±0.039
1.910±0.051
1.825±0.033
1.773±0.009
1.835±0.025
-1
0.225±0.031
0.223±0.008
0.292±0.006
0.385±0.102
0.227±0.001
0.311±0.048
EPAR (m )
42
Table 3.3: Phytoplankton percent biomass Toronto area September 2013.
-3
total biomass (g m )
HB3
LO8
LO9
IH1
IH13
L12
AB1
1325
1326
0.57
0.54
0.40
1.38
0.55
0.96
0.29
0.43
0.32
2.14
Cyanophyta
Anabaena circinalis Rabenhorst
Aphanocapsa delicatissima West &
West
Aphanocapsa elachista West & West
Aphanocapsa holsatica (Lemmermann)
Cronberg et Komarek
Aphanothece nidulans P. Richter
1.23
0.73
0.69
2.11
0.17
0.40
0.03
1.88
1.00
2.85
3.27
0.13
1.55
1.74
2.72
2.49
0.38
0.71
0.44
0.23
0.08
1.19
0.53
Cuspidothrix issatschenkoi
Cyanogranis ferruginea Hindak
6.77
0.46
1.52
0.00
Microcystis aeruginosa Kutzing
0.62
Oscillatoria sp.
0.14
Pseudanabaena limnetica Lemmermann
0.45
Pseudanabaena sp.
0.11
1.07
0.67
3.13
Rhabdoderma lineare W. Schmidle and
R. Lauterborn
Synechococcus elongatus Nageli
0.01
0.10
0.28
Synechococcus sp.
0.15
0.65
1.77
0.06
Synechocystis sp.
0.04
0.05
unknown cyanophyte
0.44
0.43
2.73
0.13
3.50
3.14
2.24
0.87
5.74
0.02
0.33
0.12
0.02
0.03
0.07
0.08
0.07
0.62
0.38
0.03
0.38
0.25
0.05
0.27
0.37
0.57
2.51
1.91
2.01
1.29
1.82
2.66
3.44
3.30
1.10
0.26
Chlorophyta
Chlamydomonas sp.
Chloromonas prona (Ettl H. et O) Silva
Closterium sp.
Coelastrum microporum Naeg
1.30
1.14
Cosmarium sp.
1.20
Dictyosphaerium pulchellum Wood
0.27
Monomastix astigmata Skuja
Monomastix minuta
0.01
0.02
Monoraphidium arcuatum (Corda) Ralfs
Monoraphidium capricornutum (Printz)
Nygaard
Oocystis parva West & West
0.10
0.05
0.01
0.04
0.12
0.10
0.15
0.14
Pediastrum boryanum longicorne
Raciborski
Pediastrum duplex West and West
Scenedesmus abundans (Kirchn.)
Chodat
Scenedesmus bijuga (Turpin) Lagerh.
0.04
0.44
0.12
0.28
0.24
6.38
0.09
0.06
4.39
1.81
0.89
0.13
0.03
Schroederia setigera (Schroeder)
Lemmermann
Selenastrum minutum (Naegeli) Collins
0.02
0.21
43
0.22
Chlorophyta (continued)
HB3
LO8
LO9
IH1
IH13
L12
AB1
1325
1326
Spermatozopsis exsultans Korschikoff
Sphaerocystis schroeteri Chodat
0.68
Staurastrum sp.
1.23
Stichococcus bacillaris Nageli
0.04
0.11
Tetraedron minimum (Braun) Hansgirg
0.27
Treubaria setigera (Archer) G. M. Smith
1.65
unknown Chlorophyte
0.86
0.54
0.12
0.54
Zygnema sp.
0.52
1.34
1.74
0.85
0.30
0.05
0.15
0.27
1.04
7.44
2.05
4.01
0.20
0.14
5.47
3.56
7.56
Chrysophyta
Bitrichia phaseolus (Fott) Fott
3.80
Chromulina sp.
0.32
Dinobryon crenulatum West and West
0.32
0.45
Dinobryon divergens Imhof
Dinobryon sociale americana
(Brunnthaler) Bachmann
Dinobryon sp.
0.30
0.04
0.42
1.34
7.33
0.42
0.69
3.18
0.30
Kephyrion sp.
Mallomonas sp.
1.32
3.22
2.92
Ochromonas sp.
unknown Chrysophyte
0.27
0.29
Haptophyta
Chrysochromulina parva Lackey
3.09
9.43
5.82
0.59
5.07
0.07
0.15
3.00
3.90
5.36
9.76
0.09
0.10
2.47
2.29
Bacillariophyta
Achnanthes minutissima Kutzing
Asterionella formosa Hass.
0.11
Aulacoseira ambigua (Grunow)
Simonsen
Aulacoseira granulata (Ehrenb.)
Simonsen
Cocconeis pediculus Ehrenb.
12.86
0.23
0.74
7.57
3.09
Cyclostephanos invisitatus (M. H. Hohn &
Hellerm.) Theriot, Stoermer & Hakansson
Cyclotella atomus Hust.
0.15
0.97
0.30
0.17
0.03
Cyclotella comensis Grunow
0.24
Cyclotella distinguenda unipunctata
(Hust.)
Cyclotella meneghiniana Kutzing
0.15
0.21
0.25
1.19
6.39
0.52
2.74
0.69
7.45
3.06
Cyclotella ocellata Pant.
0.24
Cyclotella pseudostelligera Hust.
0.08
Cymbella sp.
2.74
30.09
0.81
2.38
0.17
0.23
0.68
0.18
Cymbella silesiaca Bleisch
0.37
Fragilaria capucina mesolepta Rabenh.
2.46
Fragilaria capucina vaucheriae (Kutzing)
Lange-Bertalot
2.62
44
0.40
Bacillariophyta (continued)
HB3
LO8
Fragilaria crotonensis Kitton
LO9
IH1
IH13
L12
3.41
Navicula salinarum Grunow
0.08
Nitzschia acicularis (Kutzing) W. Smith
0.73
Nitzschia fruticosa Hassall
0.36
AB1
1325
9.42
7.91
1326
Nitzschia gracilis Hantzsch
Nitzschia linearis (C. Agardh) W. Sm.
0.08
Nitzschia palea (Kutz.) W. Sm.
0.18
Skeletonema potamos (Weber) Hasle in
Hasle & Evensen
Stephanodiscus binderanus (Kutzing)
Kreiger
Stephanodiscus niagarae Ehrenberg
0.85
Stephanodiscus parvus Stoermer & Hak.
1.20
Synedra filiformis Grunow
1.55
0.25
0.46
0.35
0.09
1.20
28.75
0.62
3.09
2.90
3.60
3.84
Tabellaria flocculosa (Roth) Kutz.
2.25
0.53
Cryptophyta
Chroomonas sp.
Cryptomonas erosa Ehrenberg.
0.14
49.65
Rhodomonas minuta Skuja
Rhodomonas minuta nannoplanctica
Skuja
4.43
41.01
30.53
2.67
1.22
6.34
2.60
6.45
1.79
27.58
57.73
2.86
1.88
5.90
5.12
7.96
1.12
1.50
24.38
5.98
12.83
3.48
42.71
6.70
5.18
Pyrrhophyta
Ceratium hirundinella Dujardin
25.29
Gymnodinium helveticum
3.48
7.47
Gymnodinium sp.
0.22
Peridinium sp.
79.21
Peridinium umbonatum Stein
8.06
2.35
1.33
9.98
Rhodophyta
Bitrichia ochridana (Fott) Bourrelly
0.39
0.06
0.36
0.05
Miscellaneous
unknown
45
0.43
1.24
3.19
Table 3.4: Phytoplankton diversity indices based on biomass. Toronto Harbour survey
September, 2013.
Species
richness
Palmer water
quality index
HB3
38
LO8
30
LO9
26
IH1
34
IH13
40
L12
36
AB1
22
1325
25
1326
30
10
10
4
12
12
9
7
4
4
Shannon
diversity
(biomass)
2.087
Evenness
based on
Shannon
(biomass)
0.4819 0.5247 0.5731
Alpha algal
biomass
3.14
2.1482 2.2645 1.0211
0.242
2.818
1.8535 2.1857 2.2057 2.5449
0.6431 0.4334 0.5776 0.5638 0.6216
2.4375 2.1445 2.5774 3.3288 2.8268 1.8355 2.0398
46
2.556
Figures
Rouge R.
Inner
Harbour
Pickering
Outer
Harbour
Don R.
Humber R.
Ashbridges
Bay
Etobicoke
Ck.
Humber Bay
5 km
Figure 1.1: Map of Toronto Region Area of Concern towed plankton survey. Inset shows a
magnified view of the Inner Toronto stations. Filled circles indicate stations locations of whole
water column vertical profiles. The dotted line indicates the towed epilimnetic survey at 3m
depth. The dashed line indicates the tow-yo transects from the surface-25m depth.
47
Figure 1.2: The SHRIMP towbody comprised of the Sea Sciences Acrobat, CTD, Rolls Royce
HR-LOPC, and YSI EXO2 sonde towed from DFO’s Leslie J. Inset graph shows a particle sizedistribution with largest counts in the 91-105 µm Equivalent Spherical Diameter bin (see text).
48
Figure 1.3: Maps of epilimnetic tows of the Toronto Region AOC for physical-chemical
properties: Temperature, Specific Conductivity, pH, Turbidity, Chlorophyll-a and Phycocyanin.
Interpolations between the tow tracks are done using MatLab’s griddata function. The upwelling
is clearly visible to the east and around Toronto Harbour.
49
Figure 1.4: Wind speed (km/h) and direction (degrees) at Toronto Pearson Airport for Aug 1-15,
2013 (from WeatherUnderground.com). The period of persistent westerly winds (270°) is given
by the bold arrows below the graphs. Times when transects were being undertaken is given by
the black bars above the graphs.
50
Figure 1.5: Screenshot of remotely sensed lake temperature from the MODIS satellite taken
from Michigan Tech Research Institute portal (www.greatlakesremotesensing.org) for Sept. 11,
2013 clearly showing a widespread coastal upwelling to the east of Toronto.
51
Figure 1.6: Magnified maps of interpolated epilimnetic tows surrounding Inner Toronto Harbour for physical-chemical properties:
Epilimnetic Temperature (1-3 m depth), Hypolimnetic temperature (4-7 m depth), Specific Conductivity, Turbidity, Chlorophyll-a and
Phycocyanin. The upwelling is clearly visible around Toronto Harbour, intruding into the nearshore of Humber Bay near the western
gap of the inner harbour. Cold hypolimnetic water coming in from the west can be seen in western portion the inner harbour along the
islands and also along the inner southern coast of the Leslie spit. Both chlorophyll-a and phycocyanin values are highest nearest the
Don River extending along the Toronto waterfront.
52
Figure 1.7: Maps of interpolated epilimnetic zooplankton counts·L-1 by size-bin from the High
Resolution Laser Optical Plankton Counter (HR-LOPC) for the Toronto Region AOC out to the
60m isobath. Total counts and bin sizes are given on the panels. Smallest particles account for
the highest percentage of the total counts with increasing size bins being successively rarer.
Smallest particle sizes are higher in the inner harbour and outer harbour whereas larger-sized
zooplankton are very rare in these areas and only found within the lake.
53
Figure 1.8: Magnified maps of interpolated epilimnetic zooplankton counts·L-1 by size-bin from the High Resolution Laser Optical
Plankton Counter (HR-LOPC) for the area surrounding Toronto Harbour (see Fig. 1.7). Total counts and bin sizes are given on the
panels. Counts of larger zooplankton size categories are only found within the inner harbour at one location along the waterfront near
the entry of the Don River. A number of patches of smaller-sized zooplankton particles are found within in the inner and outer
harbour, but not within the lake. Streaking of the patches outside of the harbour are due interpolation of the distances between the
tow tracks (see Fig. 1.1).
54
Depth m
Figure 1.9: Vertical profiles at stations (Fig. 1.1) using of the HR-LOPC within and around Toronto Harbour for temperature (red),
chlorophyll-a (green), total counts·L-1, and counts per size-bin. Stations are arranged from west (on left) to east (on right). Profiles on
the western side of the Inner Harbour and in Outer Harbour have shallower mixed depths and reduced temperatures.
55
Depth m
Figure 1.10: Vertical profiles at stations (Fig. 1.1) using of the HR-LOPC to the west (top) and
east (middle and bottom) of Toronto Harbour for temperature (red), chlorophyll-a (green), total
counts·L-1, and counts per size-bin. Profiles are arranged from nearshore (left) to offshore (right)
Profile dates are indicated on each panel.
56
Depth m
Depth m
Figure 1.11: Tow-yo of surface-25m or 2m above bottom on Sept. 9 from nearshore AB2 to TH4
(see dashed line Fig. 1.1) using griddata interpolation in MatLab with 0.25m vertical bins for (a)
temperature, specific conductivity chlorophyll-a, turbidity and (b) zooplankton particle size-bin
counts·L-1. Transect begins in the cold upwelling region with extremely low zooplankton counts
and ends near the entry to Outer Harbour with surface temperatures >10 °C than the start of the
transect and increased zooplankton counts especially in the larger size categories.
57
Depth m
Depth m
Figure 1.12: Tow-yo of surface-25m or 2m above bottom on Sept 9 from offshore L09 to
nearshore 3508 and back across Humber Bay (see dashed line Fig. 1.1) with similar output to
Fig. 1.11. The water column is consistently stratified along the transect but deeper chlorophyll-a
and zooplankton counts are found on the first half (offshore leg). Two layers of large-size counts
are seen ~5m and ~15m which are likely to be different zooplankton groups.
58
Depth m
Depth m
Figure 1.13: Tow-yo of surface-30m on Sept 13 from offshore Pickering 1330 to 1326 offshore
Ashbridge’s Bay (see dashed line Fig. 1.1) with similar output to Fig. 1.11. The water column is
more deeply stratified near the beginning of the transect. The chlorophyll-a and turbidity signal
suggest a downwelling near the end of the transect (vertical plume) which may be associated
with the edge of the upwelling. Two layers of zooplankton counts are seen ~5m and ~25m
which are likely to be different groups, but smaller size bins are only seen at depth.
59
Figure 1.14: Photo of the Lake Ontario whiting event on Aug 24, 2013 from the International
Space Station (courtesy Karen Nyberg) with stations for DFO’s Western Basin Transect for the
2013 CSMI year. The northern two stations marked in yellow are L09 and L08 (see Fig. 1.1).
Note that the whiting event, shown by the bright blue colour is absent around Toronto Harbour
along the northwestern coast of Lake Ontario. The whiting becomes more prominent near the
eastern end of the transect at Pickering (given by dashed box) and offshore at this location.
60
Depth m
Figure 1.15: Tow-yo of surface-30m from DFO’s CSMI 2013 Western Basin Transect for the northern half of Lake Ontario (see Fig
1.14) for physical-chemical values of temperature, specific conductivity, chlorophyll-a and turbidity. Surveys took place in June,
August and November. The black bar at the bottom represents the section from LO9-LO8 in Humber Bay. Humber Bay is deeply
mixed compared to the offshore and lacks the deep chlorophyll maximum (DCM) found in the offshore.
61
Depth m
Figure 1.16: Tow-yo of surface-30m from DFO’s CSMI 2013 Western Basin Transect for the northern half of Lake Ontario (see Fig
1.14) for zooplankton particle counts·L-1 by size-bin from the High Resolution Laser Optical Plankton Counter (HR-LOPC). The black
bar at the bottom represents the section from LO9-LO8 in Humber Bay. Counts of larger zooplankton are found inside Humber Bay
are seen in June (likely copepods) in a thin-layer at depth, but only very small sized zooplankton are found near surface during the
summer. Extremely low counts of all size categories are found during November just after lake turnover.
62
Depth m
Figure 1.17: Vertical profiles at the inner Humber Bay station (LO8) as part of the CSMI 2013
survey using of the HR-LOPC for temperature (red), chlorophyll-a (green), total counts·L-1, and
counts per size-bin. Surveys took place in June, August, September (this survey) and
November with day and night profiles taken in June and August. A midwater intrusion of cold
water can been seen in the Sept. profile as a result of the upwelling. Very low counts of all size
categories of zooplankton are found at this station with little vertical structure in total counts or
chlorophyll-a. Higher zooplankton counts are found in the surface in June (night) and in Sept
(day) with some indication from the day-night samples that there is overall slightly elevated
counts (but still very low) of larger zooplankton during night samples.
63
Depth m
Figure 1.18: Vertical profiles at the outer Humber Bay station (LO9) as part of the CSMI 2013
survey using of the HR-LOPC for temperature (red), chlorophyll-a (green), total counts·L-1, and
counts per size-bin. Surveys took place in June, August, September (this survey) and
November with day and night profiles taken in June and August. This station exhibits complex
temperature stratification except in November when it was well mixed. Chlorophyll-a is elevated
from the surface down into the metalimnion suggesting regular deep mixing and weak
stratification. Peaks in zooplankton counts can be seen in thin layers and concentration of larger
zooplankton (>300 µm) in the epilimnion especially during the night samples. During the
upwelling in Sept, stratification is intensified as the hypolimnion is pushed up to a much
shallower depth (~15m).
64
Figure 2.1: Location of sampling stations in western Lake Ontario during the August 2010
plankton nearshore survey undertaken by DFO. Physical parameters include station depth,
secchi depth, surface temperature, pH and algal pigments measured using a fluoroprobe.
Zooplankton samples have been analyzed from the stations indicated by the solid symbols, and
rotifers were analyzed from stations indicated by square symbols. Stations in bold and italics
were experiencing an upwelling event.
65
Figure 2.2: Location of sampling stations in the Toronto Area of Concern during the September
2013 plankton survey undertaken by DFO. Total water column (64 um) zooplankton samples
have been analyzed from stations indicated by circles. Epilimnion and metalimnion zooplankton
samples were counted separately at stations indicated by the square symbols. Additional
hypolimnetic samples were counted at deep stations, indicated by (D). Although AB3 and TH4
were deep enough to be stratified, only total water column (153 um) samples were collected due
to time constraints. Zooplankton was not counted at the station indicated by the star. The two
Pickering area stations 708 and 1329 were located farther east than is indicated on this figure,
as demonstrated by the arrows.
66
Figure 2.3: Surface temperatures (top) and secchi depth (bottom) recorded during the August
2010 survey. Stations with a U indicate the occurrence of an upwelling event on 09 August.
67
Figure 2.4: Density (top) and dry biomass (bottom) of dominant zooplankton groups in the
Toronto Harbour area in August 2010. These were 64 µm total water column samples.
Upwelling stations are indicated by a u. Veligers dominate numerically but Daphnia sp.
dominate the biomass.
68
Figure 2.5: Density (top) and dry biomass (bottom) of dominant zooplankton groups in the
Toronto Harbour area in September 2013. An E and T underneath the bar indicate epilimnetic
and total water column values, respectively. At the stations indicated by (153), a 153 µm mesh
net was used. A 64 µm mesh net was used at the remaining stations.
69
cyclo
pred clad
80
other
60
Daphnia
40
bos
*
20
21-Oct
09-Sep
24-Aug
2008
LO9
14-Aug
12-Jun
02-Sep
20-Jul
21-Apr
25-Sep
2003
03-Nov
100
10-Aug
0
28-Apr
2013
Epi
80
60
40
20
N/A
03-Nov
03-Nov
09-Sep
24-Aug
N/A
21-Oct
2008
80
2013
60
*
*
40
*
*
20
2003
09-Sep
14-Aug
12-Jun
02-Sep
21-Apr
25-Sep
20-Jul
2008
24-Aug
N/A
N/A
*
28-Apr
0
14-Aug
LO9
Total
2003
12-Jun
*
02-Sep
20-Jul
N/A
21-Oct
100
25-Sep
120
10-Aug
0
10-Aug
Zooplankton Biomass (mg m-3)
LO8
Epi
calanoid
100
120
Zooplankton Biomass (mg m-3)
veliger
28-Apr
Zooplankton Biomass (mg m-3)
120
2013
Figure 2.6: Epilimnetic (epi) zooplankton biomass at LO8 (top) and LO9 (middle) and total water
column (TWC) zooplankton biomass at LO9 (bottom). These stations were sampled seasonally
as part of the CSMI program in 2003, 2008 and 2013. For bars marked with a * veligers were
not included or were under-represented in these samples as they were taken with a 153 µm net
that did not adequately retain veligers. Only TWC nets were taken at LO9 on 14 Aug. and 03
Nov. 2013. The hypo sample was lost at LO9 on 24-Aug-2013, so the TWC biomass could not
be calculated.
70
15
10
25
1994
2000
20
2003
Pickering
708
2006
2009
15
10
5
May
Aug
Oct
Apr
Aug
Nov
May
Aug
Nov
Apr
Aug
Nov
May
Jul
Aug
Nov
0
1994
2000
2003
2006
2009
Apr
Aug
Nov
Apr
Aug
Nov
Apr
Jul
Nov
30
20
10
60
50
Inner Toronto
1364
2003
1994
2000
2006
Apr
Aug
Nov
0
Apr
Aug
Nov
Apr
Aug
Nov
Apr
Jul
Nov
May
Aug
Oct
5
40
2009
40
30
20
10
0
60
50
1994
Pickering
708 2003
2000
Apr
Aug
Nov
2009
2009
2006
2009
40
30
20
10
0
1994
Apr
Aug
Nov
2006
2006
Apr
Aug
Nov
2003
Apr
Aug
Nov
2000
Inner Toronto
1364
20
0
30
Zooplankton Density (No.L-1)
1994
Apr
Aug
Nov
25
Apr
Jul
Nov
0
30
May
Aug
Oct
20
Humber
2003
LO8
Apr
Aug
Nov
40
2000
May
Aug
Nov
60
1994
Apr
Jul
Nov
80
May
Jul
Aug
Nov
Zooplankton Density (No.L-1)
100
50
Apr
Jul
Nov
2009
336
Apr
Aug
Nov
Apr
Aug
Nov
Apr
Jul
Nov
Apr
Aug
Nov
2006
60
May
Aug
Oct
1994
0
May
Aug
Oct
120
Humber
2000 LO8
2003
10
May
Aug
Oct
140
May
Aug
Oct
May
Jul
Aug
Nov
0
20
May
Aug
Oct
bos
30
May
Jul
Aug
Nov
5
40
May
Jul
Aug
Nov
daphnia
Etobicoke
3508
50
May
Jul
Aug
Nov
other
60
May
Jul
Aug
Nov
10
Zooplankton Biomass (mg.m-3)
pred
Zooplankton Biomass (mg.m-3)
cyclo
15
Zooplankton Biomass (mg.m-3)
20
May
Jul
Aug
Nov
Zooplankton Density (No.L -1)
calan
160
Zooplankton Density (No.L -1)
Etobicoke
3508
nauplii
25
Zooplankton Biomass (mg.m-3)
veligers
30
2000
2003
2006
2009
Figure 2.7. Zooplankton density (left) and biomass (right) at nearshore Lake Ontario index
stations in the Toronto area. These were sampled by the OMOE sporadically between 1994
and 2009. Note that density at LO8 has a different scale than the other stations. Biomass at
LO8 in August 1994 was off the scale at 336 mg m-3 (primarily bosminids, cyclopoids and
Daphnia). The total water column value at each station during the September 2013 spatial
survey is shown as a broken line. The density value at Etobicoke on this date was off the scale
at 65.6 animals L-1.
71
30
800
mean length
700
density
25
20
600
500
15
400
10
300
5
200
0
100
0
-5
HH
1200
S
NW
HB
IH
Off
Ash
IH
Aug 2012
Aug 2010
IH
Sep 2013
20
18
1000
16
14
800
12
600
10
8
400
6
4
200
Daphnia Density (No L-1)
Mean Daphnia Length (um)
Cladoceran Density (No L-1)
Mean Cladoceran Length (um)
900
2
0
0
HB
IH
Off
Aug 2010
Ash
IH
IH
Aug 2012
NS
Off
East
Sep 2013
Figure 2.8: Mean herbivorous cladoceran length and densities (top) and mean Daphnia length
and densities (bottom) in Aug. 2010, Aug. 2012 and Sep. 2013. Study areas are: HB =
Humber Bay, IH = Inner Toronto Harbour, Off= offshore adjancent to Toronto, Ash = Ashbridges
Bay, NS = nearshore adjacent to Toronto, East = east of Toronto.
72
Rotifer Density (No L -1)
700
other
600
Trichocerca
Polyarthra
400
Keratella
300
Conochilus
Asplanchna
200
100
0
7
Rotifer Biomass (mg m-3)
Synchaeta
500
2047
6
1364
10.8
431
43.3
LO8
LO9
1364
1326
708
5
4
7.4
3
2
1
17.3
5.6
LO8
LO9
14.6
3.5
1364
1326
3.2
0
2047
1364
2010
431
708
2013
Figure 2.9: Epilimnetic density (top) and biomass (bottom) of dominant rotifer groups in Aug.
2010 and Sep. 2013 at selected stations. The numbers above the bars represent the percent of
total epilimnetic biomass (rotifers plus zooplankton) comprised by rotifers.
73
Rotifer Biomass (mg m-3)
8
42.5
7
other
25.4
6
Trichocerca
LO8
Synchaeta
Polyarthra
5
Keratella
4
Conochilus
3
2
12.5
1
26.8
0.6
Asplanchna
2.4
0
20-Jul
02-Sep
12-Jun
2008
24-Aug
09-Sep
21-Oct
2013
Figure 2.10: Total water column rotifer biomass at LO8 across the season in 2008 and 2013 as
part of the CSMI program. Rotifers were not sampled on 14 Aug. or 03 Nov 2013. The
numbers above the bars represent the percent of total epilimnetic biomass (rotifers plus
zooplankton) comprised by rotifers. On 20 July 2008 rotifer biomass was off the scale, with a
value of 27.6 mg m-3.
74
Figure 3.1: Phytoplankton biomass in g m-3 (top) and percent composition (bottom) at a single
station in Humber Bay and Toronto Harbour. MOE Great Lakes Nearshore Index Station
program.
75
Depth (m)
0
10
20
30
40
50
60
70
80
Temperature (°C)
17-19
15-17
13-15
11-13
9-11
7-9
5-7
3-5
Transition
zone
Figure 3.2: Water temperature profiles indicating layers of stable temperature and temperature
transition zones. Measured with an EXO2 sonde or MK9 logger September 9-13, 2013. Length
of bar indicates depth in metres. Bottom of bar on station location.
76
Temperature °C
21-23
19-21
17-19
15-17
13-15
Transition
zone
0
5
station depth (m)
Ashbridges
10
15
20
Inner
25
30
Outer
Humber
Figure 3.3: Water temperature profiles indicating layers of stable temperature and temperature
transition zones. Measured with a FluoroProbe August, 2010. Length of bar indicates depth in
metres. Top of bar on station location.
77
Mixed
Browns
Bluegreen
Green
Figure 3.4: Whole water column average chlorophyll percent composition by pigment colour
group as measured by FluoroProbe, September 2013. Bottom of bar on station location.
78
0
10
20
30
40
50
60
70
80
Station Depth (m)
Deep Chlorophyll Layer
Top of Hypolimnion
Figure 3.5. Region of increased chlorophyll within the water column as measured by
FluoroProbe September 2013. Length of bar indicates total station depth in metres. Bottom of
bar on station location.
79
100%
80%
60%
g m -3
40%
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
20%
0%
Cyanophyta
Chlorophyta
Chrysophyceae
Diatomeae
Cryptophyceae
Dinophyceae
Figure 3.6: Phytoplankton biomass (g m-3) and percent composition by biomass, September
2013. Bottom of bar on station location.
80
30
25
20
15
10
5
0
Productivity
(mg C m-3 hr-1)
% Productivity
<2 µm
2-20 µm
> 20 µm
7
6
5
4
3
Bacterial Carbon
Uptake (mg C m-3hr -1)
2
1
0
Figure 3.7: Phytoplankton and bacterial carbon uptake rates, Sep 2013. Total phytoplankton
productivity (mg C m-3 hr-1) shown in olive green, and then shown as a % contribution by size
fraction. Picoplankton (<2 µm) is green, nanoplankton (2-20 µm) is yellow and netplankton
(>20µm) is brown. Total bacterial carbon uptake is shown in blue. Bottom of bar on station
location.
81
5.50
LO9
mg C m-3 h-1
4.50
3.50
2.50
1.50
0.50
-0.50
12-Jun-13
09-Sep-13
21-Oct-13
0.9
0.8
mg C m-3 hr-1
0.7
0.6
0.5
LO8
0.4
LO9
0.3
0.2
0.1
0
June
Sep
Oct
Figure 3.8: Seasonal measures of algal productivity (mg C m-3 hr-1) at the mid shore (LO8 - 14m
depth top panel) and offshore (LO9 - 59m mid panel) stations in Humber Bay. Bacterial
Productivity is shown in the bottom panel.
82
800
700
600
500
400
300
200
100
0
HNF
APP
Bacteria
Figure 3.9: Microbial loop biomass (g m-3) and breakdown by category: Heterotrophic
Nanoflagellates (HNF), Autotrophic Picoplankton (APP) and Bacteria, September 2013.
83
Figure 3.10: Microbial loop biomass as observed in 2013 at the Humber Bay mid-shore (LO8)
offshore (LO9) and an deep offshore station (LO12). Bacteria, autotrophic picoplankton (APP)
and heterotrophic nanoflagellate (HNF) biomass is given.
84
SECTION 2: REPORT ON THE VIABILITY OF USING MOE INDEX PLANKTON SAMPLES
TO EVALUATE BUI 13: DEGRADATION OF PHYTOPLANKTON AND ZOOPLANKTON
POPULATIONS FOR TORONTO REGION AREA OF CONCERN
W.J.S. Currie and M.A. Koops
Background
In 2011, the Great Lakes Laboratory for Fisheries and Aquatic Sciences scientists was asked to
comment on the viability of using plankton samples collected as part of the Ontario Ministry of
the Environment (now MOECC, hereafter MOE) Great Lakes Nearshore Monitoring and
Assessment (hereby “Index”) program to evaluate BUI 13: Degradation of Phytoplankton and
Zooplankton Populations for the Toronto Harbour Area of Concern (hereby “TH-AOC”), which
has only a few historical plankton surveys (Patalas 1969, Haffner et al. 1982, Munawar et al.
1993). The concern at the time was that there would be too few samples to indicate any trends
since plankton are notoriously variable. It was decided by Environment Canada that the
archived plankton samples should be analyzed to determine if they were sufficient to permit an
analysis on the state of plankton populations in the AOC.
The intent of the Index network of stations is to provide a baseline time-series for determination
of trends in compounds of concern in the nearshore. Though each site is not sampled
frequently, the strength of the program is in the widespread spatial extent of stations which
cover the entire Ontario Great Lakes shoreline from Lake Superior to the St. Lawrence River.
The Index program has two objectives and three indicators:
Objectives
1) Identify temporal trends in sediment and water quality in the nearshore Great
Lakes and to use these findings to support Ministry and inter-agency efforts to
identify lake-wide or regional changes in environmental conditions, and,
2) Establish sites in each of the Great lakes removed from major point-source
influences such that the data collected at the sites may be used as a reference
when assessing environmental conditions at physically similar sites.
Indicators:
1. Concentrations of persistent contaminants in surficial sediment and in suspended
particulate material
2. Composition of benthic invertebrates
3. Physical measurements including profiles of the water column and bottom
characteristics
Great Lakes Nearshore Monitoring and Assessment (GLWQM) Draft Project
Description, Feb 3, 2009. (Todd Howell, personal communication, 2014)
In the lower Canadian Great Lakes, each Index (GLWQM) site is sampled 3 times (early spring,
summer and late fall) every 3 years. While the Index program is focused on chemical
constituents and uses only benthic organisms as indicators, MOE does collect plankton at each
Index station as part of the protocol. For phytoplankton density and taxonomy, a single depthintegrated sample of the euphotic zone (to 2x Secchi disc depth or top of metalimnion) by
lowering a “glug-glug” sampler of two, 1 L glass bottles and stored in a 500ml PET bottle with
2ml of Lugol’s Iodine as preservative. The sample was ultimately concentrated in the lab and
stored in the MOE archive facility. Zooplankton was collected using a Schindler-Patalas
plankton trap with 64 µm mesh at 3 depths (2m from the surface, mid-depth and 2m above the
85
bottom) which are pooled together and preserved using 4% sugared-formalin and 2 drops of
glycerin and archived.
This report summarizes the plankton data collected from the Index sites surrounding Toronto
Harbour AOC, statistically analyzes the distributions and composition of plankton from these
sites and makes recommendations on whether they can be used, in and of themselves, to
evaluate the status of the Biological Use Impairment (BUI) 13: degradation of phytoplankton and
zooplankton populations.
Methods and Results
The Index sites used for this analysis encompassed the boundary of the Toronto Harbour AOC:
Etobicoke (outside Western boundary), Humber Bay, Toronto Harbour (within the AOC) and
Pickering (outside Eastern boundary). Samples from Hamilton Harbour were also used to
compare with more temporally intensively sampled stations by GLLFAS Freshwater Ecosystem
Research program in 2006 and 2009.
Figure 1: Google Earth image of Index Sites used for this analysis.
The plankton samples were counted to species by experienced taxomists with a long history of
working with Great Lakes samples: Claudiu Tudorancea (Aquatic Bioservices) for zooplankton
and Hedy Kling (Algal Taxonomy and Ecology Inc.) for phytoplankton. The output of density and
composition was sent to Environment Canada and shared with this report’s authors who QA/QC
the data to assess any outliers. Summary spreadsheets were prepared that organized the
plankton composition into standardized dominant groups for comparison to other site data
collected by the GLLFAS Freshwater Ecosystem Research section. Analysis was done using R
v3.0.1 (R Core Team 2012), JMP® and Microsoft Excel 2010.
86
Zooplankton
The Index zooplankton samples were identified to species except for juvenile stages of
copepods which were identified to order. Rotifers are mentioned in notes but are not quantified.
Comments regarding sample composition and preservation can be found in Appendix 1. To
simplify the display and analysis of the zooplankton taxonomy data, major ecological groupings
of zooplankton were used in this analysis. The groupings include: cladocerans: Bosmina,
Eubosmina, Daphnia, Predaceous Cladocera (Bythotrephes, Cercopagis, Leptodora), and other
Cladocera (e.g. Holopedium, Diaphanosoma etc.), for copepods: Calanoida, Cyclopoida,
Harpacticoida, and Nauplii (initial larval stage), and Dreissenid mussel veligers (see Figs. 2-3).
Figure 2: Zooplankton densities (ind m-3). All samples analyzed for zooplankton composition
from sites surrounding Toronto Harbour AOC. ET=Etobicoke, HM=Humber Bay, TH=Toronto
Harbour, PK=Pickering. Major groupings are explained in more detail in the text.
The overall densities and biomass indicate very high variability (Figs. 2-3) but generally very low
densities as noted in comments by the taxonomist (Appendix 1). Humber Bay had the highest
counts prior to 2003, but now is comparable to most of the other sites. The very large spike at
Humber Bay in 1994 is due to high densities of the common cladoceran Bosmina. The most
complete data series from Toronto Harbour demonstrates this variability among years clearly
when comparing relatively higher counts (Fig. 2) from 2000 to extremely low counts in 2003 and
2006. The variability over the year can be seen in 2009 where the counts are extremely low in
the spring and fall and very high during the August sample. Timing can be extremely important
for zooplankton sampling since they show very high temporal variability where densities can
double in successive measurements (Mackas et al.1985).
87
Figure 3: Zooplankton biomass (mg m-3). All samples analyzed for zooplankton composition
from sites surrounding Toronto Harbour AOC. ET=Etobicoke, HM=Humber Bay, TH=Toronto
Harbour, PK=Pickering. Major groupings are explained in more detail in the text.
Species composition also indicated high variability (Fig. 4). After 1994, the spring samples are
dominated by Dreissenid mussel veligers and some copepod nauplii, but biomass is extremely
low. The summer samples have the most consistency from year to year, but even in this
sampling group, the composition can change rapidly in subsequent samples (3 years later). The
late fall samples have the highest variability in species composition with no consistency by year
of a dominant species.
Yearly species richness (number of species encountered) and diversity (index of proportion of
species found) ranges considerably since 1994 (Fig. 5). Richness and diversity can be highest
in either the summer or fall samples. Species richness was at a low in the sites from 2000 –
2003 but has increased to similar levels found in 1994 in the two sites sampled then. The
Shannon-Weiner diversity index has been relatively similar since 1994, though Toronto Harbour
had the lowest value in its series in 2009 while the neighbouring sites increased. There is no
significance to the trends (Student-t, p>0.05).
88
Figure 4: Percent composition of density by genus or group. All samples analyzed for
zooplankton composition from sites surrounding Toronto Harbour AOC. ET=Etobicoke,
HM=Humber Bay, TH=Toronto Harbour, PK=Pickering.
Figure 5: Species richness and Shannon-Weiner H' diversity by year of sampling at the Toronto
region sites.
89
Phytoplankton
The Index phytoplankton samples were identified to species when possible, but generally were
resolved to genus. Comments regarding sample composition and preservation can be found in
Appendix 2. To simplify the display and analysis of the phytoplankton taxonomy data, major
Divisions of phytoplankton were used in this analysis. The groupings include: Cyanophyta
(cyanobacteria such as Planktothrix, Anabaena), Bacillariophyta (Diatoms, e.g. Tabellaria,
Asterionella), Chlorophyta (greens, e.g. Oocystis), Chrysophyta (golden-brown algae, e.g
Dinobryon, Ochromonas), Cryptophyta (Cryptomonad, e.g. Cryptomonas), Dinophyta
(dinoflagellates, e.g. Ceratium, Peridinium) and Euglenophyta (e.g. Euglena) (see Fig. 6).
-3
Phytoplankton Density (m )
Figure 6: Phytoplankton densities (counts m-3). All samples analyzed for phytoplankton
composition from sites surroundingToronto Harbour AOC. ET=Etobicoke, HM=Humber Bay,
TH=Toronto Harbour, PK=Pickering. Major groupings are explained in more detail in the text.
The overall counts and biomass indicate very high variability (Fig. 6-7), with some sites showing
higher biomass in recent years. Biomass tends to be lowest in the early spring sample and
highest in the mid-summer. Rapid changes in species composition or biomass are common in
phytoplankton populations. Toronto Harbour had the highest biomass in 1994 due to high
counts of a mixed bloom of large-sized dinoflagellates (primarily Ceratium but also Peridinium)
which account for much greater biomass per individual, but is generally at or near biomass
found at the other sites. Counts in the Toronto Harbour site have been much higher since 2006
compared to previous years.
90
-3
Phytoplankton Biomass (mg m )
Figure 7: Phytoplankton biomass (mg m-3). All samples analyzed for phytoplankton composition
from sites surroundingToronto Harbour AOC. ET=Etobicoke, HM=Humber Bay, TH=Toronto
Harbour, PK=Pickering. Major groupings are explained in more detail in the text.
Figure 8: Percent composition of biomass by major algal group. All samples analyzed for
phytoplankton composition from sites surrounding Toronto Harbour AOC. ET=Etobicoke,
HM=Humber Bay, TH=Toronto Harbour, PK=Pickering. Groups are the same as from Fig. 7.
91
While the cyanophyta counts account for more than 50% of the total counts, these cells are
generally very small so account for only a small proportion of the biomass (Fig. 7). A difference
can be seen when comparing the Humber Bay and Toronto Harbour to the other sites when
biomass is displayed as percentage by major group (Fig. 8), where higher percentages of
dinoflagellates occur in these sites more regularly.
Species richness and diversity cannot be correctly calculated for phytoplankton as they were for
zooplankton since taxonomic identification is mixed in that, while some species were identified,
it is done mostly only to genus or to major group (e.g. “Tiny chrysophyte flagellates”).
Statistical Analysis
The number of sampling events is not even by year or by site which complicates analyses
(Tables 1-2). The only years where all sites were sampled equally for zooplankton are 2006 and
2009. Humber Bay and Toronto Harbour were sampled in 1994, when 4 samples per year were
taken, but a 6 year gap exists until 2000 where only Toronto was sampled once in fall 1997.
This gap was a period of major changes to the Lake Ontario ecosystem with the introduction
and expansion of Dreissenid (both Zebra and Quagga) mussels and the introduction of the large
predaceous cladoceran Cercopagis pengoi. Phytoplankton samples available from the Index
program are even more sparse than those of zooplankton (Table 2) and most of the early
samples before 2003 are of questionable condition (Appendix 2).
Table 1: Dates and number of zooplankton samples from each Index station.
Site
Years Sampled
N = # samples
Etobicoke
2006,2009
6
Humber Bay
1994,2000,2003,2006,2009
16
Toronto Harbour
1994,1997 (once), 2000,2003,2006,2009
17
Pickering
2000,2003,2006,2009
12
Table 2: Dates and number of phytoplankton samples from each Index station.
Site
Years Sampled
N = # samples
Etobicoke
2006,2009
5
Humber Bay
1994, 2006
4
Toronto Harbour
1994,1997, 2003,2006,2009
11
Pickering
2003
2
To compare zooplankton densities, the data were log transformed to account for unequal
sample sizes and profoundly unequal variance. Even with transformation, differences between
sites for zooplankton densities could not resolved (Repeated Measures ANOVA, p>0.40) in part
due to a strong yearly signal (p<0.05) and a highly significant difference between sampling
season (spring, summer, fall p<0.001) (see Fig. 7). This indicates that the plankton density
changes more due to successive samples at a given site than between sites (extremely high
variability between samples). It cannot be determined if the reduction in zooplankton that
occurred between 2000-2003 is a trend or a local minimum. Attempts to resolve any differences
by site using seasonal grouping (e.g. spring only) reduced the-within error variability, but were
still not significant (p>0.05). Attempts to use MANOVA to resolve any changes in ecological
groups of zooplankton could not be accomplished due to uneven samples, low N and strong
sample variability.
92
Log Total Count
Log Total Count
Figure 7: Output showing log-transformed mean zooplankton density values (left) for the
Toronto area sites and the ANOVA interaction plot by year (right). Within a given year and
between years, densities can vary by several orders of magnitude and trends cannot be
determined with confidence.
To compare phytoplankton biomass and counts, the data were log transformed to account for
unequal sample sizes and radically unequal variance. A Repeated Measures ANOVA was done
by using each year as an independent realization, using season as the repeated sample, and
comparing the sites. No differences were found when using density or biomass data (p>0.4).
The only difference found was in biomass using a two-factor ANOVA for Site (p=0.033) with the
Pickering-Toronto combination accounting for the majority of the difference (Tukey HSD,
p=0.038). The finding is questionable however since Pickering had only 2 measurements (Fig.
9) from 2003 and the variances are significantly different (p<0.01). Attempts to resolve any
differences by site using seasonal grouping (e.g. spring only), were still not significant (p>0.05).
Attempts to use MANOVA to resolve any changes in ecological groups of phytoplankton could
not be accomplished due to uneven samples, low N and strong yearly variability.
93
Figure 8: Output showing log-transformed mean phytoplankton biomass values (left) for the
Toronto area sites and the ANOVA interaction plot (right). There is less variability year to year in
phytoplankton density (~ 4 orders of magnitude) compared to zooplankton.
Figure 9: Box plots of phytoplankton density (counts m-3). Upper and lower bars are maximum
and minimum with outliers (>3/2 of upper quartile) marked with circles. Dark line is the median.
The left plot gives boxplots for each year that a site has more than 2 measurements, while the
right plot is for all years combined for each site. Some years have extremely low counts.
94
Figure 10: Box plots of phytoplankton biomass (mg m-3). Upper and lower bars are maximum
and minimum with outliers (>3/2 of upper quartile) marked with circles. Dark line is the median.
The left plot gives boxplots for each year that a site has more than 2 measurements, while the
right plot is for all years combined for each site.
Figure 11: Power analysis graph of sample size required for a given number of comparisons
using a two-tailed ANOVA test of means with α=0.05. Output is from the R function anova.test in
the package pwr.
95
A power analysis was done to estimate the number of samples needed to give sufficient power
in an ANOVA at α=0.05, given the number of site comparisons (Fig. 11).
Moderate power is generally given to be approximately 0.7 - 0.8, so for 4 sites, the number of
samples collected at each site to detect a difference of one of the sites would be N = 38-44. To
detect a difference between two sites, for instance inner Toronto Harbour to an outside
reference site, the number of samples would be 51 – 64 per site under the same conditions.
This could be done by increasing the temporal or spatial sampling (e.g. sampling at multiple
stations within the AOC and/or more often).
Hamilton Harbour Case Study
To evaluate the number of samples needed to resolve the seasonality of plankton populations, a
case study was done using Hamilton Harbour. This site has the advantage of being sampled by
both MOE and DFO for 2 years (2006 and 2009) using similar methodology but DFO samples
13 samples per year while MOE samples 3 times per year. One methodological difference is the
sampling depths at the station. HH258 is a 23m station but MOE collects 3x 30L Shindlers (2,
11, 21m) giving approximately 90L sampled. DFO collects 11x 40L Schindlers (1,3,5,7,9,11,13,
15,17,19,22 m) for about 440L. The consequence is that DFO sampling is more likely to collect
depth strata that might have high biomass (such as near the thermocline) and have a greater
chance of collecting rare species.
Zooplankton densities for DFO and MOE are shown in Fig. 12. The first obvious finding is that
the large Bosmina longirostris spike in late spring (end of May-June) is missed by the MOE
sampling. This is important because Bosmina is the most dominant zooplankton by count and
biomass over the season in most embayment locations. The MOE samples are almost devoid of
Bosmina entirely. The MOE overall yearly density and biomass estimate subsequently are half
of that estimated from DFO sampling. When DFO’s sampling is divided into spring, summer and
fall samples to match those of the MOE, DFO mean density and biomass are still above that of
MOE (Fig. 13) using Welch’s non-parametric test of means (allowing unequal variance, p<0.01).
The summer MOE sample is the closest for density or biomass estimates, but it underestimate
veliger counts, likely due to vertical patchiness of their distribution. The early spring sample is so
early that it catches mostly nauplii and copepodids of calanoid copepods (Fig. 14). The late fall
sample is reasonably good for species composition, but it underestimates the density, possibly
due to differences in methodology (number of Schindlers taken). This is conservative finding for
BUI#13 since phytoplankton communities change even more rapidly over time (Dermott et al.
2006).
96
Figure 12: Zooplankton density (counts m-3) for Hamilton Harbour. The 13 DFO samples are
shown in the filled area graph while the MOE samples are shown by the stacked bars. Dark
filled arrow indicate the yearly average for DFO, the outlined arrow average for MOE samples.
97
Figure 13: Zooplankton density (counts m-3) and biomass (mg m-3) comparison for spring,
summer and fall samples. Error bars are ±SE. For DFO, those designated spring are the first 4
biweekly samples, summer are the next 5, and fall are the last 4.
Figure 14: Zooplankton percent composition for DFO and MOE sampling of Hamilton Harbour
central station for 2006 and 2009 combined.
98
By subsampling the DFO biweekly sampling series, it is possible to determine the necessary
number of samples to capture both species composition and counts (Fig. 15). To match MOE
sampling timing as closely as possible, the first and last sample taken in the season were
always used, with the rest of the samples being as evenly spaced as possible, chosen by
selecting the closest mid gap sample. In order to capture the Bosmina peak in June and July
(Fig. 12), it is necessary to take at least 5 samples and preferably 6 over the course of the
season. There is an overestimate of the Bosmina densities when using 5 samples because one
of five samples falls exactly on the biomass peak. Both the 3 and 4 samples treatment evenly
spaced over the year underestimate the density and biomass (~ 60%) and suggest the Bosmina
composition is only 17% of the density when it is in fact 50% and 13% of biomass rather than
26%. Using 6 samples equates reasonably to monthly sampling.
Figure 15: Estimates of density (left) and biomass (right) for zooplankton composition in
Hamilton Harbour central station in 2006 as a function of number of subsamples of the total
possible 13 samples. To most closely match MOE protocol, the first and last sampling dates
were always used.
Summary
Major points:
 Zooplankton densities are very low at almost all of the sites as noted by the taxonomist
(Appendix 1).
 A viewing of the taxonomist notes indicated that some sites may not be effective as a
reference site for Toronto Harbour. The inner harbour is a protected site which differs
considerably from Etobicoke which is exposed coastal. Etobicoke shares similar
comments with Oakville (included in Appendix 1) in that it has very few rotifers, which
are much more common in protected waters. This effectively suggests that the site has a
different food-web than Toronto.
 The MOE Index samples are unevenly distributed by year and site resulting in difficulties
for examining the data statistically. Furthermore, even if uneven variance and
unbalanced design are ignored and a statistical analysis run, there are too few samples
to make a determination on differences in zooplankton or phytoplankton populations by
sampling site.
 A power analysis indicated that at least 50-60 samples would be needed from each site
to resolve differences between 2 locations (within AOC to a reference site).
 The comparison of DFO to MOE sampling frequency in Hamilton Harbour indicated that
the 3 samples taken per year by MOE is insufficient to account for changes in species
composition and density over the sampling season. It is recommended that monthly
sampling is necessary for zooplankton to give at least 6 samples per sampling year.
Phytoplankton have higher variability so are likely to require more frequent samples.
99
References
Dermott, R., Johannsson, O., Munawar, M., Bonnell, R., Bowen, K., Burley, M., Fitzpatrick, M.,
Gerlofsma, J., and Niblock, H. 2007. Assessment of lower food web in Hamilton Harbour,
Lake Ontario, 2002 - 2004. Can. Tech. Rep. Fish. Aquat. Sci. 2729: 120 p.
Google Earth V 7.1.2.2019. (May 9, 2013). Toronto, Canada, 43° 23.176'N 79° 54.672' W, eye
alt 74 km. NOAA. First Base Solutions 2014, Digital Globe 2014, TerraMetrics 2014.
http://www.earth.google.com [April 22, 2014].
JMP®, Version 10. SAS Institute Inc., Cary, NC, 1989-2007.
Haffner, G. D., Poulton, D. J. and Kohli, B. 1982. Physical processes and eutrophication.
Water Res. Bull. 18: 457-464.
Mackas, D.L., Denman, K.L., and Abbott, M.R. 1985. Plankton Patchiness - Biology in the
Physical Vernacular. Bulletin of Marine Science 37(2): 652-674.
Munawar, M., Munawar, I. E., McCarthy, L., Page W., and Gilron, G. 1993. Assessing the
impact of sewage effluent on the ecosystem health of the Toronto Waterfront (Ashbridges
Bay), Lake Ontario. J. Aquat. Ecosystem Health 2: 287-315.
Patalas, K. 1969. Composition and horizontal distribution of crustacean plankton in Lake
Ontario. J. Fish. Res. Board Can. 26: 2135–1462.
R Development Core Team (2008). R: A language and environment for statistical computing. R
Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL
http://www.R-project.org.
100
Appendix 1: Zooplankton taxonomist comments regarding sample viability/composition
Toronto Harbour
DATE: 940713, Rotifers very numerous both in number of taxa and as numerical abundance
DATE: 000516, Extremely poor sample in number of organisms.
DATE: 030430, A very poor sample in number or organisms.
DATE: 030730, A very poor sample in terms of number of organisms.
DATE: 061116, Poorly preserved and also very poor in terms of number of organisms sample.
DATE: 090424, A very poor sample in terms of number of organisms.
DATE: 090810, Algal bloom.
DATE: 091109, Very few rotifers.
Humber Bay
DATE: 001005,
DATE: 031201,
DATE: 030430,
DATE: 030730,
Rotifers very numerous.
An extremely poor sample in number of organisms
Rotifers extremely rare
Rotifers very numerous. Asplanchna sp. and Synchaeta sp. extremely
numerous.
DATE: 060427, A poor sample in number of taxa and specimens.
DATE: 090424, A poor sample in terms of number of organisms.
DATE: 090810, Algae very numerous.
Etobicoke
DATE: 061120,
DATE: 090424,
DATE: 090810,
DATE: 091109,
Pickering
DATE: 000529,
DATE: 000831,
DATE: 001016,
DATE: 030501,
DATE: 030811,
No rotifers.
Rotifers very few
Algal bloom.
Rotifers not many
DATE: 060515,
DATE: 061121,
DATE: 090429,
DATE: 091109,
A very poor sample in number of taxa and individuals.
Keratella cochelaris extremely numerous.
a very poor sample in number of taxa and specimens.
an extremely poor sample in terms of number of organisms. No rotifers.
a sample dominated by Bosmina longirostris. Otherwise the sample was poor
in number of taxa and specimens.
a very poor sample in number of organisms. One single Keratella cochlearis
occurred in the entire sample.
an extremely poor sample in number of organisms.
a very poor sample in number of organisms. Very rare rotifers
an extremely poor sample in number of organisms.
an extremely poor sample in number or organisms. Rotifers very few
Oakville
DATE: 940512,
DATE: 000517,
DATE: 000810,
DATE: 060428,
A sample very poor in number of taxa and specimens. Very few rotifers.
Extremely poor sample in terms of number of organisms. Rotifers very rare
A very poor sample in number of crustaceans. Rotifers very numerous
An extremely poor sample in terms of number of organisms.
DATE: 031204,
101
Appendix 2: Phytoplankton taxonomist comments regarding sample viability.
Coloured flags were assigned based upon the taxonomist comments and composition of the
sample. Red indicates serious degradation or dissolution resulting in a sample that is
unsatisfactory and likely to be biased. A yellow flag indicates that caution should be used when
using this sample in analysis.
SITE
FLAG
COMMENT
Toronto Harbour
13-Jul-94
25-Aug-94
10-Nov-94
28-Oct-97
30-Apr-03
30-Jul-03
03-Dec-03
27-Apr-06
15-Aug-06
24-Apr-09
10-Aug-09
09-Nov-09
Not well preserved.. Dinobryon cells out of lorica.. Lorica counted and cell size
estimated.. Plant remains starch and amorphous mass detritus masses.
Poorly preserved.. Detritus and broken fecal material .. Diatoms disolving but not as bad
as some others.
High plant material flocculent detritus.. Decomposing zoo remains.. Dissolution ..
Pseudfeces..
Fungal hypae present indicating that the sample became unpreserved prior to sending
for analysis.. Very low density, diatom frustules gone.. High detritus- mucilagae clumps ,
theca of Ceratium present but no complete cells
Plant remains, empty benthic diatoms poor preservation .. With degradation.. Biomass
seems like it might be under estimate.. Also lots of empty Dinobryon
Very sparse not healthy cells.. Near shore sample.. High detritus, fecal pellets, silty clay
and Plant material cuticles, marsh pollen and starch grains
mucilaginous clumps and plant remains.. Lots of benthic algae.. Probably from near
shore erosion.
Plant remains, Empty lorica of Dinobryon sociale v. americanum, empty benthic diatoms,
mats of benthic chlorella( not include in biomass ~ 84*60 and 160^2 cells 3-6um in size)
High clay and detritus .. No picos counted
Mucilaginous clumping.. Plant remains.. Some empty benthics - possible near shore
erosion .. Epiphytic taxa
Humber Bay
12-May-94
13-Jul-94
26-Aug-94
10-Nov-94
30-Apr-03
30-Jul-03
01-Dec-03
27-Apr-06
11-Aug-06
08-Nov-06
24-Apr-09
10-Aug-09
09-Nov-09
Plant debris.. Diatom dissolution.. Often only chloroplasts remain or ghosts of the
frustule. ..Poor preservation.. Or differentational preservation.
Diatoms dissolving.. Pseudokephyrion and Dinobryon lorica present but protoplast
shrunk of disappeared. ( Dinobryon included in count as some protoplasts still present.
Poor preservation .. Biomass likely an under estimate as difficult to ID remains of cells.
No count for pico blue or greens .. Due to high flocculent detritus. .. Si dissolution
Biomass probably significant under estimate… detritus and mucilaginous detritus.. Poor
preservation.. Diatoms dissolving .. Not good count at 10x due to only protoplasts left for
diatoms. .
Some diatoms with dissolution and dinobryon empty.. ( recycled .. Also benthic
epiphytic taxa present and empty .. Only recently live counted)
Plant material, littoral clumps of detritus , very little plankton and mostly empty frustules
( only live counted)
Plant remains and diatoms very thin and dissolving
Dinobryon Najakjaurensis present but empty.
Still not great shape but better than the samples of 1994.
Plant remains present diatoms very thin
Pseudofeces and clumps of phytoplankton, empty benthic algae. Chrysophytes not in
good shape.. Most dinobryon had left lorica.. Too much time between sampling and
preservation!
Lots of benthic bacteria present
102
(Appendix 2 continued)
SITE
FLAG
COMMENT
Etobicoke
28-Apr-06
14-Aug-06
24-Apr-09
10-Aug-09
09-Nov-09
Pickering
01-May-03
04-Dec-03
Mucilangious benthic material, plant scales and fibers and empty benthic diatoms
Some detritus and plant material, seems too low to be real, either concentrating error for
original sample or a dilution due to excessive ppt or run off
Very high detritus.. Need to dilute extra to ID and enumerate algae.
-
Very low biomass.. Lots of plant material .. Diatom frustules dissolved..
Very little in samples.. A bit of plant scales and detritus.
103
SECTION 3: REPORT ON PLANKTON SURVEYS RELATED TO THE THUNDER BAY AOC
K.L. Bowen, H.A. Niblock, and W.J.S. Currie
Introduction
In 1987 the International Joint Commission identified Thunder Bay Harbour on Lake Superior as
an Area of Concern (AOC). The main concerns in the AOC were degraded water and sediment
quality associated with pulp and paper mill and wood preservation plant operations, grain mill
operations and the Thunder Bay sewage treatment plant (Richman 2004; RAP 1991). These
include discharges directly to Thunder Bay Harbour and into the lower Kaministiquia (Kam)
River, which flows into Thunder Bay. The main contaminants of concern include dioxins/furans,
polycyclic aromatic hydrocarbons (PAHs), creosote, polychlorinated biphenyls (PCBs) and
mercury (InfoSuperior 2015). The Thunder Bay AOC includes approximately 28 kilometers of
Lake Superior shoreline and extends up to nine kilometers offshore from the City of Thunder
Bay, including the Welcome Islands (Fig. 1) (EC and OMOE 2011). The primary beneficial use
impairments (BUI) that have been identified include sediment contamination and degradation of
benthos, fish consumption advisories, impairments to fish populations and loss of species
diversity, and loss of recreational value (e.g., beach closures) (RAP 1991). The BUI
“degradation of zooplankton and phytoplankton populations” was assumed to be impaired in the
2005 Stage 2 RAP report, but it was not assessed prior to that determination (EC and OMOE
2011). Given the lack of available data on plankton in Thunder Bay Harbour, it has been given
the status of “requires further assessment”.
To advance knowledge of plankton in Thunder Bay, a 2005 study of total phosphorus (TP) and
chlorophyll a was carried out by OMOE (Benoit et al. 2012). This study concluded that
conductivity, TP and total Kjeldahl nitrogen (TKN) was elevated as a result of urban inputs in the
nearshore study area, particularly in the deltas of the Kam and McKellar Rivers, but TP levels
had improved in comparison to earlier studies (e.g., Anderson 1986, Richman 2004). Levels
have likely further declined since 2005 following improvements to sewage treatment and
operational reductions at the Bowater Abitibi pulp mill. Benoit et al. (2012) also showed rapid
dilution of TP farther away from the river deltas, and that chlorophyll a levels were low and
relatively unchanged over the years. They concluded that the area remains oligotrophic and
there should be no issues with nuisance algae. While this study is useful in addressing the
eutrophication BUI (#8), it does little to directly assess the plankton population BUI #13,
especially zooplankton. They recognize that “knowledge of chlorophyll and phosphorus in the
study area does not provide proof of healthy phytoplankton and zooplankton biomass in
Thunder Bay. More information on plankton community composition would be needed to make
that assessment overall”. The Great Lakes Laboratory for Fisheries and Aquatic Science was
approached in 2014 to process archived plankton samples from the OMOE Nearshore Index
Program, but it has been determined that these samples are insufficient to assess BUI 13 in and
off itself (see Section 2).
There is fairly limited published information on phytoplankton and zooplankton populations in
Lake Superior (e.g. Barbiero et al. 2001; Watson and Wilson 1978; Munawar and Wilson 1978;
Yurista et al. 2009; Munawar and Munawar 1978; Munawar et al. 1978; Munawar et al. 1987;
Munawar and Munawar 2000; Munawar and Munawar 2009; Reavie et al. 2014; Munawar et al.
2015) and very few studies have included the Thunder Bay area. The intention of this report is
to present and summarize the limited amount of zooplankton and phytoplankton data that is
available to date from the Thunder Bay area. This has been assembled with the other, relatively
more numerous, data from coastal, offshore and embayment areas in Lake Superior. We have
reviewed available literature, searched Environment Canada’s STAR database at the Canada
104
Centre for Inland Waters (CCIW) in Burlington ON for relevant information, and compiled data
from several unpublished studies conducted by federal and provincial agencies in Canada and
the United States. In some cases, we have taxonomically enumerated previously uncounted
archived zooplankton samples.
Survey Procedures
1971 and 1973 Great Lakes Biological Laboratory Surveys
In 1970 and 1971, comprehensive lakewide surveys were undertaken in lakes Huron, Erie,
Ontario and Superior by the Great Lakes Biological Laboratory at CCIW in Burlington, Ontario.
Watson and Carpenter (1974) reported that in Lake Huron in 1971, zooplankton were collected
using a 64 µm mesh, 40 cm diameter Wisconsin net, from a maximum depth of 50 m or 2 m off
bottom at shallower locations. No corrections were made for net efficiency. One third of each
sample was used for zooplankton counts, one third for determining organic material weight, and
one third for determining the amount of chlorophyll a in the net sample. For zooplankton
analysis, the sample was well mixed and two or more 1 mL subsamples were taken with a widebore pipette. A minimum of 200 animals (excluding nauplii, the first juvenile stage of copepods)
were counted and identified. In all of the studies reported here, zooplankton were preserved in
4% sugar buffered formalin.
We have made the assumption that 1971 Lake Superior samples were collected the same way
as the Lake Huron samples described in Watson and Carpenter (1974). Although some
sampling information and physical / chemical data for the Superior samples were available in
Environment Canada’s Star database at CCIW, no zooplankton data were found. Watson
(1974) also stated that no firm estimates were available for Lake Superior, indicating these
samples were never originally counted. However, many of these zooplankton samples remain in
the Fisheries and Oceans Canada (DFO) archival facility at CCIW. We counted archived
samples from three stations (station 48 within the Thunder Bay AOC, and coastal stations 45
and 50) from early May and early July 1971 (Fig. 1, Table 1). Each sample was homogenized,
and two or three 1 mL subsamples were drawn with a Henson-Stempler pipette. A minimum of
300 animals were enumerated from each sample in a Bogorov counting chamber, including
nauplii. Cladocerans were identified to genus, and copepods were classified as cyclopoid,
calanoid or nauplii. Lengths of up to 35 calanoids and cyclopoids were measured in each of
these samples. Mean weights of cladoceran taxa (weighted for density) were taken from the
2011 Superior CSMI data described below. Length-weight regression equations used in
biomass calculations are described in Bowen and Johannsson (2011).
In 1973, the Great Lakes Biological Laboratory at CCIW undertook one of the most
comprehensive sampling programs to date in Lake Superior, completing six surveys through the
May to November period (Watson et al. 1975, Watson and Wilson 1978, Munawar and
Munawar 1978). Each survey, they measured temperature, chlorophyll a and chemistry at about
144 stations, and collected zooplankton at 80 sites. They collected zooplankton in the same
manner as in 1971, except samples were taken from a maximum depth of 100 m. These
stations included 139 within the offshore portion of current boundaries of the Thunder Bay AOC,
138 and 137 at the mouth of Thunder Bay, and 133, 142 and 144 in the coastal area between
the mainland and Isle Royale (Fig. 1, Table 1). Sample information, physical, chemical data, and
densities and biomass of main zooplankton groups (calanoids, cyclopoids and cladocerans)
were obtained from the Star database. Nauplii were not counted in these samples.
Phytoplankton samples were taken from water collected from 0-20 m using an integrating
sampler at 34 stations across the lake including stations 139 and 144. Samples were preserved
in Lugol’s iodine solution and F. Munawar identified species using a phase contrast inverted
microscope (Utermohl 1958) using multiple magnifications such that all species present were
counted. At least 200 entities were counted. Integrated water samples were also incubated to
105
measure uptake of 14C in order to estimate total and size fractionated primary productivity as
described in Munawar et al. (1978).
USGS June Surveys
As part of their June fish survey work, the Lake Superior Biological Station of the United States
Geological Survey (USGS) from Ashland WI has sampled a number of coastal sites in Lake
Superior, ranging in depth from 20 to 130 m (Table 2). Water depth, surface and bottom water
temperatures were taken at the start and end of each trawling transect. A single total water
column 50 cm diameter 64 µm zooplankton net was also taken at the offshore end of each
transect. Samples taken in 1990, 1991 and 1992 at up to 33 stations were counted by an
unknown contractor to species if possible. Juvenile copepods were only identified as
“copepodids” in 1990 and 1991, but as “calanoid copepodids” or “cyclopoid copepodid” in 1992.
Additional archived samples from five stations in the Thunder Bay area collected in 2001-2003,
2013 and 2014 were obtained by DFO and counted, as described for the 1971 samples above.
Stations 401 to 403 are located in Thunder Bay and ranged from 43 to 80 m deep, 407 is in
Black Bay to the east (29 m deep), and 400 is a coastal station to the west (64 m deep) (Fig. 1).
OMOE Index Survey
In 1999, 2005 and 2011, the Ontario Ministry of Environment and Climate Change (hereafter
OMOE) surveyed two index sites in the Thunder Bay area in spring, summer and fall (Fig. 1,
Table 1). These included Welcome Island (284) within Thunder Bay, and Flatland Island (283),
a protected coastal station just south of Thunder Bay. Sturgeon Bay (285), a coastal site to the
east, was also sampled in 2005 and 2011. Depths at these three sites averaged 17, 7 and 10 m
deep, respectively. At each site, three 30 L Schindler-Patalas traps with a 64 µm sock were
collected 2 m from the surface, mid-depth and 2 m above the bottom of the water column and
pooled. Zooplankton in these samples were identified to the species level if possible, counted
and measured by taxonomist C. Tudorancea as described in Bowen and Johannsson (2011).
More details of the OMOE Index program are provided in Section 2. Various water chemistry
parameters were also measured as part of this program (N. Benoit, Ontario Ministry of the
Environment, Toronto, ON, personal communication, 2012), although we obtained results from
the OMOE only for the 2005 year.At these same sites, integrated water samples were collected
and preserved with Lugol’s iodine solution for phytoplankton enumeration. Samples were
collected using a ‘glug-glug’ sampler over the euphotic zone (2 x Secchi or to the top of the
metalimnion if stratified). Phytoplankton samples were counted by Hedy Kling following methods
described in Findlay and Kling (1996).
OMNR 2005 Embayment Surveys
Lake Superior was the focus of intensive lake-wide monitoring programs in 2005 and 2011 as
part of the multi-agency, binational Cooperative Science Monitoring Initiative (CSMI). As part of
this program, the Ontario Ministry of Natural Resources and Forestry (hereafter OMNR)
undertook spring, summer and fall surveys at four embayments in 2005, under the supervision
of T. Johnson, Research Scientist OMNR. Three stations along a depth gradient of 10 m, 50 m
and 100 m water depth were sampled at each of Thunder Bay (south of Pie Island), Nipigon
Bay, the Apostle Islands and the Duluth MN area (Figs. 1 and 2, Table 1). All of the 10 m deep
stations were within 0.5 km of shore. Given the steep bottom slope in coastal Lake Superior, the
100 m deep stations were at most only 4 km from shore. Secchi readings and a Hydrolab profile
(temperature, conductivity and pH) were generally taken at each station. More details of this
study are provided in Dietrich (2006).
Total water column zooplankton were collected from each station using either a 64 µm, 40 cm
diameter net or a 153 µm, 50 cm diameter net, as outlined in Table 7. All of the available
Thunder Bay samples and a subset of the 10 50 and 100 m deep samples from the other areas
106
were enumerated by taxonomist J. Foster, using the methods reported in the OMOE survey
above. Nauplii counts are not provided due to inconsistencies in net mesh size, as they are not
adequately captured by 153 µm mesh.
2001 Surveillance Survey
In 2001, in partnership with EC’s surveillance program on board the CCGS Limnos DFO
sampled 9 stations in May and 14 stations in August (Table 3a). Samples were collected with an
integrating sampler from 0-20m and preserved in Lugol’s iodine solution. Samples were
enumerated by F. Munawar using the inverted microscope Utermohl technique (Utermohl 1958)
and a minimum of 200 entities were counted. Integrated water samples were also incubated
onboard with 14C to estimate size fractionated primary productivity as described in Munawar et
al. (2009).
2011 CSMI Survey
In 2011 as part of a lake wide CSMI survey, DFO sampled 16 stations in Lake Superior from
late July to early August, and 10 stations from late September to early October (Fig. 2, Table
3b). This was in partnership with EC’s surveillance program on board the CCGS Limnos. A
single total water column zooplankton sample was taken at each site using a 50 cm diameter
153 µm net. These were taken to a maximum depth of 100 m, or 2 m off bottom at shallower
stations. These were enumerated as described in the OMOE survey above. Temperature
profiles and Secchi readings (during daylight hours only) were also taken on the surveillance
cruises. Integrated water samples were collected from 0-50 m in spring and summer and 0-20m
in fall. Samples were incubated with 14C to estimate size fractionated primary productivity as
described in Munawar et al. (2009).
Results and Discussion
Physical / Chemical Parameters: Temperature
Embayments in Lake Superior such as Thunder Bay begin warming more quickly in the spring
than coastal and offshore areas, which gives zooplankton production in these protected areas a
head start relative to the open lake. For example, during the early June surveillance cruise by
EC in 2005, temperature at station 139 was 8.4 °C, compared to only about 3 °C offshore.
During the USGS surveys in the early 1990s, June surface temperatures in Thunder Bay
averaged about 12 °C at nearshore stations 401 and 402, and were slightly cooler (7.9 °C) at
403 near Pie Island due to its closer proximity to open water (Table 2). Temperatures in Black
Bay ranged between 10.5 °C at the mouth to 15.7 °C in the protected inner bay. Western
Nipigon Bay (stations 412 to 414) was also relatively warm (about 13 °C) compared to the
stations 415-417 in the eastern area (7-10 °C). Eastern coastal stations were only around 3 °C
in June. Southern and western coastal stations were intermediate in surface temperature,
ranging from 5 to 8 °C. Monthly sampling in the early 1970s shows that in May, the Thunder Bay
sites were similar in temperature to adjacent coastal areas, but by June they were beginning to
warm relative to the lake (Tables 4 and 5). They tended to stay warmer through the summer
months, but by October, the embayment stations were again similar to the coastal sites. This
shows the lag effect in season in Superior; the coastal sites remain cool even in July, and
temperatures in mid-September are still indicative of summer conditions.
The OMNR embayment sampling in 2005 showed that in early June, both the Nipigon Bay (NB)
and Thunder Bay (TB) sites had just started warming at the 10 m deep stations (Table 6), but
temperatures were still ≤5 °C. Surface warming was evident at the Dululth sites by mid-June (78 °C). By mid-July, the TB stations had reached 16-18 °C at the surface, but the upper water
column was still unstable as temperature declined rapidly with depth. Epilimnetic temperatures
ranged from 14 to 17 °C at the TB sites through the summer, and the epilimnion had deepened
to >20 m by late September. Even in mid-October, the surface was still 14 °C, and the
epilimnion had reached a depth of about 37 m at TB50. The highest temperatures during the
107
OMNR survey were observed at the NB sites in early August (19 °C) and the Apostle Island (AI)
sites in early September (18 °C). The coastal Duluth sites remained cooler, reaching only 6-10
°C in mid-August and about 13 °C in early September.
During the 2011 CSMI lakewide survey, epilimnetic temperature at 139 in Thunder Bay was 16
°C in early August and 13 °C in late September (Table 3b). Epilimnetic temperatures at the
coastal stations were similar, ranging from 16 to 21 °C in the summer and 10 to 17 °C in the fall.
Although epilimnetic temperatures in the offshore were generally cooler than the coastal
stations in the summer (9 to 18 °C), they were more similar in the fall (10 to 15 °C).
Secchi Depth
Secchi depth, an indicator of water clarity, is generally quite low in the Kam River delta area due
to tributary inputs of sediment and DOC, and increases farther offshore. Benoit et al. (2012)
reported secchi depths of only 0.3 to 2 m in the river and delta, and values between 1.3 and 7 m
beyond the delta. Secchi values ranging from 4 to 6 m were observed in Thunder Bay during the
early 1970s (Tables 4 and 5). The lowest value (1.5 m) was observed on 2-Jun-1971 at station
48, indicating relatively high turbidity at that location. Coastal Secchi depths usually ranged
between 9 and 14 m in May and June 1971, and between 5 and 9 m from July to October. In
2005, the OMOE Thunder Bay stations 283 and 284 were also turbid in mid-May (Secchi = 1.3
m) and again at 283 in early October (1.2 m) (Table 7). Station 283 is shallow and may be
experience shoreline turbulence, whereas both 284 and 48 are closer to the City of Thunder
Bay and may be influenced by discharge from the Kaministiquia (Kam) River. The Thunder Bay
OMOE stations were less turbid during August, with Secchi depths of 4-6 m. Water clarity at
Sturgeon Bay (Station 285) was moderate, ranging from 3-4.8 m. Unfortunately, physical and
chemical data were not readily available from the OMOE stations in 1999 and 2011.
In contrast, water clarity was greater at Thunder Bay area sites farther from the Kam River
during other 2005 surveys. Secchi readings at station 139 were about 8 m in both early June
and mid-August 2005 (CSMI, EC Surveillance). The OMNR Thunder Bay area stations were
located to the south of Pie Island and also appeared to be more indicative of Lake Superior
coastal conditions. On 30 May, Secchi was 9.8 m at TB10, 11.3 m at TB50 and 16.8 m at
TB100. This was the highest Secchi value observed during the 2005 OMNR surveys. On the
remaining dates, Secchi at the TB sites ranged from 7.2 to 12.6 m. Water tended to be clear at
Duluth and the Apostle Islands in summer and fall, with Secchi depths ranging between 9.0 and
13.8 m. Water clarity in Nipigon Bay was generally lower, with Secchi depths between 5.6 and
9.2 m. During the summer 2011 CSMI survey, water clarity was generally high, with Secchi
depths ranging from 8 to 13 m in the coastal areas, and 11-16 m in the offshore (Table 3). In the
fall, offshore values were 8 to 12.5 m. Fall Secchi depth at the Duluth station (221) was only 2.5
m, and 6 m at 139 in Thunder Bay.
Water Chemistry
In the early 1970s, TP values were often slightly elevated in Thunder Bay (2.8 to 7.7 µg L-1)
relative to adjacent coastal areas (1.9 to 6.1 µg L-1) (Tables 4 and 5), but were still within the
oligotrophic range (Vollenweider et al, 1974, after Wetzel, 2001). The highest value was
observed during a turbid spring day in 1971 at station 48 near the Kam River mouth, and was
likely due to sediment loading. Soluble reactive phosphorus (SRP) was also very low in in the
early 1970s, usually under 1.5 µg L-1. Turbidity was also generally below 1 FTU. In 2005, TP
was elevated at the OMOE sites in May (12.3 to 23.3 µg L-1), and at 283 in October (11.7 µg L-1)
(Table 7). However, this coincided with higher turbidity and much of this likely represented
phosphorus bound with suspended sediment. Phosphate phosphorus, the dissolved fraction
available for algal uptake, was generally ≤1 µg L-1. During the EC 2005 surveillance cruises, TP
values at Station 139 in June (4.4 µg L-1) and August (3.0 µg L-1) were in the same range as
seen offshore (EC Star Database, CCIW). In May 2001, TP at stn 139 was higher than the
108
offshore, while in August it was in the same range as offshore stations. Benoit et al. (2012)
reported elevated phosphorus in the immediate area of the Kam River delta and along the inner
harbour adjacent to the city (e.g., 6-54 µg L-1). Levels quickly diminished farther offshore,
ranging from 6 to 16 µg L-1 in the spring and 3 to 8 µg L-1 in the summer and fall. Jackson et al.
(1990) also showed that TP and other nutrients in the Thunder Bay area were similar to other
Canadian shoreline sites in Lake Superior.
Total chlorophyll a values were also very low (≤2.2 µg L-1) in the Thunder Bay area throughout
the 1973 season (Table 5), again indicating oligotrophic conditions. In 2005, values for this
parameter were similar, ranging between 1.4 and 3.8 µg L-1 at OMOE stations 283 and 284, and
1.8 µg L-1 or less at 285 (Table 7). EC Star Database data from 2001 show 139 with the highest
chl a value in the August cruise although it was still very low. Benoit et al., (2012) also showed
that chlorophyll levels were low in the Thunder Bay area in 2005, with median values ranging
from 1.1 to 2.7 µg L-1. The highest concentrations were generally observed in the nearshore
adjacent to the City of Thunder Bay.
Phytoplankton
Biomass and Community Composition
The seasonal aspect of the phytoplankton community in offshore Thunder Bay (station 139) was
captured during the 6 surveys undertaken in 1973 where biomass increased through spring to a
peak in late July and remained relatively stable through to December (Table 8, Fig. 3). Total
biomass was ultra-oligotrophic at all dates, with a peak of 277 mg m-3 in July and a low of 51 mg
m-3 in October. All cruises (except July) were dominated by Cryptophyceae (26-78% of the total
biomass), closely followed by Chrysophyta (9-40%) and Diatomeae (3-47%, Fig. 3).
Rhodomonas minuta was common throughout the year and composition did not change much
through the season (Table 8, Munawar and Munawar, 1978). The total biomass observed at 139
and 144, the two stations in the Thunder Bay area, are in the range of open lake stations but did
not come close to the peaks in biomass observed in the western arm stations (Fig. 4).In 1983,
total phytoplankton biomass at stn 139 remained in the ultra-oligotrophic range, at less than 300
mg m-3, but was more constant throughout the year than it was in 1973 showing no defined
peak (Fig. 3). As in 1973, the annual average of 250 mg m-3 at this offshore Thunder Bay station
was in line with the biomass at other offshore stations across the lake which averaged 253±44
mg m-3 in June and 224 ±13 mg m-3 in September (Fig. 4) and was lower than the biomass
observed near Duluth. There was a more even mix of taxa in the biomass in 1983 with less
contribution by Cryptophyceae and increased Diatomeae and Chrysophyceae (Munawar and
Munawar, 2000). Chlorophyta were still low and constant throughout the year (Fig. 3).
Phytoplankton biomass at 139 was in the oligotrophic range in May 2001 (1943 mg m-3) and
slightly eutrophic in August (3332 mg m-3, Fig. 3), which is a large increase in overall biomass
from the earlier surveys (Munawar and Munawar, 2009). Composition in May and August was
dominated by Diatom taxa (57% and 76% biomass) and the importance of Cryptophycea had
completely diminished (4% biomass). Chrysophyceae still contributed 13 and 20% to the total
phytoplankton biomass measured. Another interesting change is that while the Thunder Bay
station was in line with other offshore stations in 1973 and 1983, in 2001 it contained the highest
biomass (Fig. 4), surpassing even the nearshore station at Duluth (221) which had much higher
biomass than Thunder Bay in 1973 and 1983.
2001 spring biomass at 139 was dominated by Asterionella formosa Hassall while summer
biomass was dominated by Tabellaria fenestrata (Lyngb.) Küetzing and Tabellaria flocculosa
(Roth) Küetzing. There were 80 taxa identified in the May cruise (Table 9). Of these, 5 were
oligotrophic indicators and 8 were eutrophic indicators (Munawar and Munawar 2009). In August
there were 122 taxa of which 10 were oligotrophic indicators and 11 eutrophic indicators. The
biomass of the oligotrophic indicators was higher than the eutrophic indicator in both months.
109
Phytoplankton taxonomic data from Thunder Bay offshore station 139 showed an increasing
trend in biomass from ultra-oligotrophic in 1973 to mesotrophic in 2001. A shift in percent
composition was also apparent with decreased unicellular flagellated Cryptophycea and
increases in Diatoms (Fig. 6). This station also shifted from having biomass similar to other
offshore stations and much lower than the west end /Duluth area stations in 1973 and 1983 to
having the highest observed biomass in 2001.
Phytoplankton biomass from samples collected during the seasonal OMOE index surveys in the
Thunder Bay area in 1999, 2005 and 2011 are presented in Fig. 7. At all 3 locations and
seasons total biomass appears to be increasing or holding steady over this time period. Overall
the biomass is in the ultra-oligotrophic range and so much lower than the values measured in
2001 by Munawar and Munawar (2009). Composition is dominated by Diatoms and
Chrysophyceae at all stations and dates and this is similar to the 2001 sampling by Munawar
and Munawar (2009).
Species composition is given in table 10. The Chrysophyte genera Ochromonas and
Pseudopedinella are common at all stations, Tabellaria and Fragillaria Diatoms are very
common. Cryptophytes Cryptomonas and Rhodomonas are found at all stations but at higher
biomass in the Welcome and Flatland Islands sites compared to Sturgeons Bay.
Phytoplankton productivity
Phytoplankton productivity averaged between 1.08 and 2.06 mg C m-3 hr-1 across Lake Superior
during cruises from June through December, 1973 (Fig. 5) with a low of 0.27 to a high of 12 mg
C m-3 hr-1 (Munawar et al. 1978). The primary productivity at station 139 was consistently higher
than the monthly average and was the highest value recorded in the lake for the JuneSeptember (Fig. 5). Activity coefficient or productivity to biomass ratios (P:B) averaged across
Lake Superior from June through December, 1973 ranged between 2.16 and 2.68 (g C m-3 d-1 /
g Biomass m-3) x10-1 with a low of 0.25 to a high of 6.62 (g C m-3 d-1 / g Biomass m-3) X10-1
(Munawar et al. 1978). Productivity to biomass was variable at 139 being highest in the lake in
June, higher than average in September and October and lower than average in July and
December. In 1983 productivity was not estimated in the Thunder Bay area. Lakewide primary
productivity was higher than in 1973 and averaged 2.6 ± 0.48 mg C m-3 hr-1 in July and 4.7±
1.12 mg C m-3 hr-1 in August.
In 2001, lakewide average primary productivity averaged 0.46± 0.05 mg C m -3 hr-1 in May and
1.11 ± 0.12 mg C m-3 hr-1 in August (Munawar and Munawar 2009). Station 139 had the highest
rate recorded in May and second highest in August (Fig. 5). Average productivity in May was
dominated by the mid-sized nano-plankton (2-20 µm, 55%) followed by small pico (>2 µm, 37%)
and then net (>20µm, 7%) plankton while productivity at station 139 was more of a mix of size
classes with more of the large plankton than average (26%). In August, lakewide average
productivity had relatively more mid (65%) and large (14%) sized plankton compared to May.
Station 139 showed different conditions with 47% of the productivity coming from the largest
size category. Taxa that would be included in this large category are colonial or chain forming
species such as Tabellaria fenestrata, a large chain forming Diatom that was a 47% of the
phytoplankon biomass in August (Table 9).
In 2001, lake wide average P:B was higher in August (1.2 ± 0.16 mg C m-3 d-1 / mg Biomass m-3)
than in May (0.5 ± 0.05 mg C m-3 d-1 / mg Biomass m-3). The Thunder Bay station was fairly
consistent in spring and summer at 0.47 and 0.54 mg C m-3 d-1 / mg Biomass m-3 in May and
August respectively. In 2011, primary productivity was measured during summer and fall cruises
and the lakewide average was 1.12 ± 0.12 mg C m-3 hr-1 in summer and 0.62 ± 0.09 mg C m-3
hr-1 in October (Fig. 5) (Munawar et al. 2015). The 2011 summer lake wide averages were
110
almost exactly that found in 2001. The productivity at station 139 was very close to the lakewide
average, with values of 1.23 and 0.58 mg C m-3 hr-1 in summer and fall respectively.
Rates of primary productivity declined at station 139 over the 1973 to 2011 time period (Fig. 6)
and were consistently dominated by the <20 µm sized algae. While there appeared to be an
increase in netplankton in 2001 compared to summer 1973, the nanoplankton became more
important in the 2011 sampling. More frequent sampling is needed to determine trends.
Zooplankton
Zooplankton Density, Biomass and Community Composition
Zooplankton community composition in Thunder Bay and elsewhere in Lake Superior is
seasonal in nature, and the timing of seasonal succession is influenced by temperature.
Generally, densities and biomass are low in the spring, peak in the summer, and begin declining
in the fall. Overall, Lake Superior zooplankton densities are low compared to most other Great
Lakes sites (Watson and Wilson 1978, Barbiero et al. 2001). Zooplankton species richness was
relatively low at all of the Lake Superior sites, especially in the offshore. When juvenile forms
that were not identified to genus or species were excluded, only 11 taxa were identified at the
offshore sites in both summer and fall (Table 12). At the coastal sites, the number of taxa
increased to a maximum of 19 in the fall. Most of the same taxa were found in Thunder Bay as
the coastal sites, although richness was slightly less in Thunder Bay, with a maximum of 16 taxa
in the summer. Taxa richness at the other embayment sites ranged from only 6 taxa at Duluth in
the spring, to 19 taxa at Nipigon in the spring. The number of taxa is partly dependant on the
number of samples counted (Table 11), as rare taxa are more likely to be encountered as the
number of samples increases.
Copepod nauplii (larvae which were not consistently identified as cyclopoid or calanoid) were
often numerically a dominant part of the zooplankton community in Lake Superior, especially in
the spring (Table 11, Figs. 5, 12 and 13). The highest nauplii densities observed within Thunder
Bay occurred in June and July 1971 (Fig. 8) and May and July 1999 (Fig. 13), when densities
ranged from 12 213 to 20 673 ind m-3. Nauplii densities also intermittently fell between 5 000
and 12 000 ind m-3 during the spring USGS surveys at the Thunder Bay area sites (Fig. 12).
However, values were usually <5000 ind m-3 during most surveys. Nauplii comprised about 84%
of total zooplankton density at spring coastal sites but only 4% at offshore fall sites. In Thunder
Bay, napulii made up 71% of total density in the spring, 23% in the summer, and 22% in the fall.
However, they were generally unimportant in terms of biomass due to their small size,
comprising ≤ 6% of the total, or <1 mg m-3 (Table 12). However, this group was not always
captured effectively, through the use of coarse mesh (153 µm) in plankton nets, or counted in all
surveys, especially those in the offshore and the other embayments.
When nauplii were excluded, zooplankton densities in Thunder Bay averaged 1183 ind m-3 in
the spring, 15 992 ind m-3 in the summer, and 3966 ind m-3 in the fall, based on 1990 to 2011
surveys (Table 11). Thunder Bay values were about twice as high as those seen at the coastal
stations, and summer values were about 10 times higher than in the offshore. In fact, the
Thunder Bay summer mean was the highest density observed in any area in Table 11. The
highest spring zooplankton densities (excluding nauplii) were found in Black Bay (4243 ind m-3)
and Nipigon Bay (2 903 ind m-3), comprised mostly of cyclopoid and calanoid copepods (Fig.
10).
Zooplankton biomass of Lake Superior tends to be higher and more variable in nearshore areas
than in the offshore. For example, Yurista et al. (2009) reported late summer 2006 means of 41,
17 and 22 mg m-3 for station depths of <30 m, 30-150 m and >150 m, respectively. For the
studies summarized in this report (Table 12), zooplankton biomass in coastal areas of Lake
Superior was low in the spring (mean = 6 mg m-3), increased in the summer to about 20 mg m-3,
111
and declined in the fall to about 10 mg m-3. Mean spring and fall values in Thunder Bay were
similar to the coastal areas, but summer biomass in Thunder Bay reached an average of 64 mg
m-3 between 1999 and 2011. Thunder Bay area sampling by OMOE in 1999, 2005 and 2011
showed zooplankton biomass <4 mg m-3 in the spring, and higher biomass in the summer (1959 mg m-3) and fall (7-33 mg m-3) (Fig. 13). In recent years, the highest biomass values were
seen in the OMNR 2005 samples; particularly the 50 m deep Thunder Bay coastal site in early
August (123 mg m-3 at TB50) and the shallow Apostle Island site in late October (95 mg m-3 at
AI10) (Fig. 14). Over the whole study period, the highest biomass was found at Station 48 in
Thunder Bay in early July 1971, at 154 mg m-3 (Fig. 8). In contrast, biomass in Thunder Bay
never exceeded 30 mg m-3 throughout the 1973 sampling season (Fig. 9), and averaged 10-20
mg m-3 (Watson and Wilson, 1978). During the 2011 CSMI summer and fall cruises,
zooplankton biomass in Thunder Bay, the Apostle Islands and Duluth were about two or more
times higher than elsewhere in Lake Superior (Fig. 15). This was driven largely by increases in
cyclopoid copepods and Daphnia in these protected areas. The highest CSMI values were seen
at Thunder Bay in fall 2011 (47 mg m-3). Offshore CSMI values averaged 10 and 12 mg. m-3 in
summer and fall, respectively.
Calanoid copepods are generally the most dominant group by biomass found in Lake Superior
due to their relatively large size, comprising on average between 51 and 94% in coastal and
offshore areas of Lake Superior (Table 12), and most species are indicative of oligotrophic,
cool-water conditions (Balcer et al., 1984). The lowest proportion of calanoids was seen in Black
Bay in the spring (28%), but generally calanoids comprised between 40 and 89% of zooplankton
biomass in the embayments. In spite of this, mean calanoid densities rarely exceeded 5000 ind
m-3 (excluding nauplii). Numbers tended to be lowest in the spring (<1200 ind m-3) and peaked
in the summer. The highest mean summer value observed was in Thunder Bay (5476 ind m-3),
and means ranged between 2200 and 4200 ind m-3 at the other coastal and embayment sites.
At the coastal sites, calanoids comprised 65% of total density in the spring, 32% in the summer
and 41% in the fall. The proportion of calanoids in Thunder Bay tended to be less than the
coastal sites in the spring and fall, but similar in the summer. Calanoids were also the most
commonly encountered group at offshore sites, but their densities averaged only 1025 ind m-3 in
the summer (85%) and 1886 ind m-3 in the fall (73%) (Fig. 15).
Leptodiaptomus sicilis was the most common calanoid species in the spring at the coastal,
offshore, Thunder Bay and Nipigon sites. Limnocalanus macrurus was another dominant
species, especially in the offshore and coastal areas. Both species prefer the hypolimnion of
large, cold, deep lakes (Balcer et al., 1984). Leptodiaptomus minutus, a small cool-water
calanoid, was common at the Apostle Islands and Duluth sites throughout the season, and at
the Thunder Bay and Nipigon sites in the fall. Calanoid copepodids (juvenile forms not identified
to species), were also important, comprising between 9% (Black Bay) and 65% (offshore) of the
total density (excluding nauplii). Leptodiaptomus siciloides, a calanoid indicative of warm
eutropic embayments, was only found occasionally at the Duluth and Apostle Island sites, and
was absent at the remaining sites.
Cyclopoid copepods were usually less dominant than calanoids in Lake Superior, especially at
the offshore and coastal sites. In terms of density (excluding nauplii), they comprised between
13% to 20% and 25% to 48% in the two areas, respectively (Table 11). They were less
important in terms of biomass due to their smaller size (5% to 27%). In the embayments, they
tended to be most dominant in the spring, especially in Black Bay (82% by density) and Thunder
Bay (51%). The highest mean cyclopoid abundances were seen in Thunder Bay in the summer
and Duluth in the fall (around 4500 ind m-3), and means ranging between 2000 and 3500 ind m-3
were recorded in the other nearshore areas. Almost all of the cyclopoids identified to species
were Diacyclops thomasi. This is a common, cool water species that prefers the thermocline
112
(metalimnion) during stratified conditions (Stewart 1974). It is predatory, consuming other small
zooplankton (Balcer et. al, 1984). Occasionally Mesocyclops edax and Acanthocyclops vernalis
were found at the embayment and coastal sites. Cyclopoid copepodids (juveniles) were
common, but these were probably almost all D. thomasi.
Cladocerans were the third dominant zooplankton group at the Superior sites, with the highest
densities seen in the embayments in summer and early fall (Fig.s 9, 13-15). These values
ranged from 1000 to 5000 ind m-3, with the highest density seen in Thunder Bay in summer.
They were more abundant in warmer, more protected locations (such as upper Black Bay and
upper Nipigon Bay) earlier in the spring (Figs. 10 and 11). In Thunder Bay, they were
uncommon in the spring, but reached about 30% of total density in the summer and fall (Table
11). In the coastal areas, they comprised only about 1% of zooplankton density (excluding
nauplii) in the spring, but 20% to 34% later in the season. Cladoceran density and biomass
remained low in the offshore throughout the year (Fig. 15), reaching a mean of only 177 ind m -3
( 7% of total density) by the fall. The proportions of cladocerans by biomass (Table 12) were
usually fairly similar to those of density. In the embayments and coastal areas, the most
common cladocerans during the warmer months were Daphnia retrocurva and Bosmina
longirostris. Daphnia galeata mendoate and Eubosmina coregoni tended to dominate in the fall,
along with Holopedium gibberum in the coastal areas. These three latter taxa were also the
most dominant cladocerans in the offshore. All are herbivores, filtering phytoplankton and other
microscopic organisms. The invasive predatory cladoceran Bythotrephes was ocassionally
found.
Veligers, the larval form of Zebra and Quagga mussels (Dreissena sp.) were rare in the
Superior zooplankton, especially at the coastal sites, though veligers are under-sampled when
using 153 µm mesh nets. They were not found offshore. They reached their highest proportion
of total density (excluding nauplii) in Thunder Bay during the summer (7%), although they
comprised only 2% of biomass due to their small size.
Summary of Existing Zooplankton Data
Embayments in Lake Superior such as Thunder Bay and Nipigon Bay tend to warm more
quickly in the spring and reach higher temperatures in the summer than adjacent coastal areas.
This, combined with slightly higher nutrient levels, results in earlier seasonal succession and
higher overall zooplankton densities and biomass in the embayments. Temperature appears to
be an important driver of zooplankton biomass in nearshore Lake Superior (Yurista et al. 2009;
Watson and Wilson 1978). This is particularly evident with cladocerans such as Bosmina and
Daphnia and cyclopoid copepods. Populations of these taxa tend to develop first in the
nearshore and spread offshore as the summer progresses (Watson and Wilson, 1978). In the
studies summarized here, Thunder Bay generally supported the highest zooplankton
populations in Lake Superior. However, total phosphorous and chlorophyll results suggest that
Thunder Bay is still usually in the oligotrophic range. Zooplankton densities and biomass values
in Thunder Bay are also very low relative to more productive areas in the lower Great Lakes.
For example , seasonal mean biomass values in eutrophic embayments in Lake Ontario such
as the Bay of Quinte and Hamilton Harbour are approximately an order of magnitude higher
(Bowen and Johannsson 2011; Dermott et al. 2007). The zooplankton communities in these
enriched southern areas are usually dominated by cladocerans, particularly Bosmina,
Eubosmina and Daphnia. In contrast, calanoid copepods tend to dominate in Lake Superior,
even in the embayments. Zooplankton species richness in Thunder Bay and elsewhere in Lake
Superior is generally quite low, with the community dominated by a few species. Most of the
calanoid copepods found tend to be indicative of cold, nutrient-poor environments.
Unlike the other Laurentian Great Lakes where dramatic changes in zooplankton populations
have been observed over the last 40 years (e.g. Lake Ontario, Lake Michigan (Barbiero et al.
113
2014; Vanderploeg et al. 2012), the zooplankton community in the Thunder Bay area of Lake
Superior appears to have been relatively stable since the early 1970s (Fig. 16). However,
determining long term temporal trends is challenged by year to year variability, lack of
consistency in sampling station locations, and a general paucity in long-term data.
Conclusions
This report presents all available plankton data from the Thunder Bay area, and compares to
other embayment, coastal and offshore areas in Lake Superior. However, most of the Thunder
Bay area stations summarized here are either located outside of the AOC boundaries (e.g.,
OMOE’s 283, OMNR’s TB10, TB50 and TB100 and USGS’ 401 and 402), or are at the
southern, coastally influenced portion of the AOC (EC-DFO’s 139 and USGS 403), as shown in
Fig. 1. Very few plankton samples have been collected from the AOC in close proximity to the
City of Thunder Bay and the Kam River, where human impacts are most likely to occur. Fig. 16
highlights the infrequency of zooplankton sampling within the AOC, starting in 1971. The closest
station to the river mouth is OMOE’s Welcome Island (284), and it has only been sampled nine
times over a twelve year period. Furthermore, even this station is still too far outside the zone of
eutrophication, based on the TP and chlorophyll results in Benoit et al. (2012). Turbidity (as
indicated by Secchi disk depth) and TP were intermittently elevated at stations 48 (sampled in
1971 only) and 284; stations in the southern part of the AOC and those south of Pie Island
appear to be more coastal in nature and less indicative of AOC conditions. Although the USGS
has sampled a number of sites in Thunder Bay and the surrounding coastal areas since 1990,
June is not an ideal time to sample zooplankton in Lake Superior as the lake is still very cold
and the zooplankton not very diverse. Zooplankton populations tend to be fairly homogeneous
early in the season, consisting of calanoids and Diacyclops thomasi which persist year-round
(Watson and Wilson 1978). Most differences among areas develop through the summer as
cladocerans and other taxa preferring warmer temperatures appear.
In order to properly assess whether phytoplankton and zooplankton populations within the
Thunder Bay AOC are impacted, it is necessary to sample the areas where impacts are most
likely to occur, such as locations close to the river mouth and areas with historically
contaminated sediment such as the North Harbour area (Cole Engineering, 2014; Benoit et al.
2012). The Thunder Bay RAP identified the Kam River, the inner Thunder Bay Harbour and
Chippewa Beach as the areas of highest degradation, with impacts radiating out from the river’s
delta (Ontario Ministry of Environment et al. 1991; Richman 2004). Sampling should be carried
out at several stations along a gradient away from the most impacted areas, as shown in Benoit
et al. (2012). Sampling would also need to be done repeatedly over the course of one or more
seasons, with emphasis on the July to September period when the zooplankton community is
most developed. This would provide data on spatial variability within Thunder Bay harbour, and
determine if a trophic gradient exists. Data contained in this report could be used as a baseline
or reference for any new studies.
114
Acknowledgements
All of the authors would like to acknowledge the contributions of a number of individuals who
provided data, gave support or improved the manuscript. Many people were instrumental in
completing work in the field and lab and assisting with data analyses and guidance, including
DFO’s Mark Fitzpatrick, Robin Rozon, Angela Wilson, Marten Koops and Ora Johannsson. The
phytoplankton, primary production and microbial loop findings were carried out under the
supervision of DFO’s Mohi Munawar. Other agencies were also vital to the completion of this
project. We would like to thank Environment Canada’s (EC) Technical Operations staff and the
captains, officers and crew of DFO research vessels over the years, including the CCGS
Limnos and the Martin Karlsen. We appreciate the contributions of the Lake Superior CSMI
researchers, including Jack Kelly and Glen Warren of US Environmental Protection Agency,
Jason Stockwell of the US Geological Survey (USGS) and Alice Dove of EC. Thanks to Lori
Evrard of the USGS office in Ashland WI for providing samples and data from their nearshore
trawling program, and to DFO’s Gavin Christie for sample delivery. Appreciation goes to Nadine
Benoit (OMOECC) for supplying details on the Index Sampling Station program, and to the
OMOECC field crews for sample collection. Thanks go to Tim Johnson, Jason Dietrich and
other field crew members of the Ontario Ministry of Natural Resources and Forestry for
coordinating and implementing the 2005 embayment study, and to E.J. Isaac for finding the long
lost samples. We appreciate the efforts of N. Watson, J. Wilson and G. Carpenter of the Great
Lakes Biological Laboratory in Burlington, Ontario and their technicians for the 1970s research,
and to EC for providing these data from the STAR database at CCIW. Thanks to Claudiu
Tudorancea, Jodi Foster and Amanda Conway for zooplankton and rotifer sample enumeration
and taxonomy. Funds were secured through Environment Canada under the Great Lakes Action
Plan, upon request from the Thunder Bay RAP and research base funding at DFO GLLFAS.
115
References
Anderson, J. 1986. Nearshore Water Quality at Thunder Bay, Lake Superior, 1983, Ministry of
Environment. Queen’s Printer for Ontario.
Balcer, M.D., Korda, N.L., Dodson, S.I. 1984. Zooplankton of the Great Lakes. A guide to the
identification and ecology of the common crustacean species. University of Wisconsin
Press, Ltd., Madison, Wisconsin.
Barbiero, R.B., Little, R.E., and Tuchman, M.L. 2001. Results from the U.S. EPA’s Biological
Open Water Surveillance Program of the Laurentian Great Lakes: III. Crustacean
Zooplankton. J. Great Lakes Res.27:167-184.
Barbiero, R.B., Lesht, B.M., Warren, G.L. 2014. Recent changes in the offshore crustacean
zooplankton community of Lake Ontario. J. Great Lakes Res., 40:898–910.
Benoit, N., George, T., Boyd, D., and Baker, S. 2012. Assessment of total phosphorus and
chlorophyll in Thunder Bay, 2005. Ministry of the Environment, Environmental Monitoring
and Reporting Branch. February 2012.
Bowen K.L., Johannsson, O.E. 2011. Changes in zooplankton biomass in the Bay of Quinte
with the arrival of the mussels Dreissena polymorpha and D. rostiformis bugensis, and the
predatory cladoceran Cercopagis pengoi:1975-2008. Aquat. Ecosyst. Health Manage.
14:44-55
Cole Engineering, 2014. Sediment Management Options Evaluation – Final Report. Thunder
Bay North Harbour, City of Thunder Bay. Prep. for EcoSuperior Environmental Programs.
Dermott, R., Johannsson, O., Munawar, M., Bonnell, R., Bowen, K., Burley, M., Fitzpatrick, M.,
Gerlofsma, J., Niblock, H. 2007. Assessment of lower food web in Hamilton Harbour, Lake
Ontario, 2002 - 2004. Can. Tech. Rep. Fish. Aquat. Sci. 2729:120 p
Dietrich, J.P., 2006. Lake Superior Food Web Study Summary Report I. Ontario Ministry of
Natural Resources, Glenora Fisheries Station, Picton, Ontario. 21 pp.
Environment Canada and the Ontario Ministry of the Environment, 2011. Thunder Bay Area of
Concern – Status of Beneficial Use Impairments September 2010. PIBs 8232e, Queen’s
Printer for Ontario.
Findlay D. L., Kling, H.J. 1996. Protocols for Measuring Biodiversity: Phytoplankton in
Freshwater Lakes. URL https://www.researchgate.net/publication/264881321_
Protocols_for_measuring_biodiversity_Phytoplankton_in_freshwater
InfoSuperior, 2015. Lake Superior Information Network – Thunder Bay.
http://infosuperior.com/thunder-bay/
Jackson, M.B., Vandermeer, E.M., Heintsch, L.S. 1990. Attached filamentous algae of northern
Lake Superior: Field ecology and biomonitoring potential during 1983. J. Great Lakes Res.
16:158-168.
Munawar, M., Munawar, I.F. 1978. Phytoplankton of Lake Superior 1973. In: M. Munawar
(ed.), J. Great Lakes Res. Internat. Assoc. Great Lakes Res., 4:415-422.
Munawar, M., Munawar, I.F. 2000. Chapter 1. Lake Superior: Phytoplankton composition,
parameters, and ecological implications. In: Phytoplankton dynamics in the North American
Great Lakes, Vol. 2. Lakes Huron, Superior, & Michigan. Ecovision World Monograph
Series. Backhuys Publishers, Amsterdam, The Netherlands. pp 1-70.
Munawar, I.F., Munawar, M. 2009. Phytoplankton communities of Lake Superior 2001:
Changing species composition and biodiversity of a pristine ecosystem. In: M. Munawar, I.F.
Munawar (Eds.), State of Lake Superior. Ecovision World Monograph Series, Aquatic
Ecosystem Health & Management Society, Burlington, ON.pp.319-359.
Munawar, M., Wilson, J.B. 1978. Phytoplankton - zooplankton associations in Lake Superior. A
statistical approach. J. Great Lakes Res. 4:497-504.
Munawar, M., Munawar, I.F., Culp, L.R., Dupuis, G. 1978. Relative importance of
nannoplankton in Lake Superior phytoplankton biomass and community metabolism. In: M.
Munawar (ed.), J. Great Lakes Res., and 4:462 480.
116
Munawar, I.F., Munawar, M., McCarthy, L.H. 1987. Phytoplankton ecology of large eutrophic
and oligotrophic lakes of North America: Lakes Ontario and Superior. In: M. Munawar (Ed.),
Proc. Internat. Symp. on Phycology of Large Lakes of the World. Arch. Hydrobiol. Beih.
Ergebn. Limnol./ Advances in Limnology, 25:51 96.
Munawar, M., Munawar, I. F., Fitzpatrick, M., Niblock, H., Lorimer, J., 2009. The base of the
food web at the top of the Great Lakes: Structure and function of the microbial food web of
Lake Superior. In: M. Munawar, I.F. Munawar (Eds.), State of Lake Superior. Ecovision
World Monograph Series, Aquatic Ecosystem Health & Management Society, Burlington,
ON. pp.289-318.
Munawar, M., Fitzpatrick, M., Niblock, H. 2015. Exploring planktonic dynamics in the deeper
strata of the Laurentian Great Lakes. Oral presentation at the Great Lakes of the World VIII.
March 24-25, 2015. Mangochi, Malawi. Aquatic Ecosystem Health & Management Society.
RAP 1991. Thunder Bay Area of Concern Remedial Action Plan Stage 1: Environmental
Conditions and Problem Definition. Ontario Ministry of the Environment, Environment
Canada, Ontario Ministry of Natural Resources, Department of Fisheries and Oceans.
September 1991.
Reavie, E.D., Barbiero, R.P., Allinger, L.E., Warren, G.J. 2014. Phytoplankton trends in the
Great Lakes, 2001-1011. Journal of Great Lakes Research 40:618-639.
Richman, L.A. 2004. Great Lakes Reconnaissance Survey - Water and Sediment Quality
Monitoring Survey: Harbours and Embayments Lake Superior and the Spanish River.,
Ontario Ministry of the Environment. PIBs 4865e, Queen’s Printer for Ontario.
Stewart, J.A. 1974. Lake Michigan zooplankton communities in the area of the Cook nuclear
plant. In The biological, chemical and physical character of Lake Michigan in the vicinity of
the Donald C. Cook nuclear plant. (Eds.), E. Seible, Ayers, J.C. pp. 211-232. Univ. Mich.
Great Lakes Res. Div., Spec. Rep. 51.
Utermöhl, H. 1958. Zur vervolkommnung der quantitativen phytoplankton-methodik. (The
improvement of quantitative phytoplankton methodology. In German.) Mitt. Internat. Verein.
Limnol. 9:1-38.
Vanderploeg, HA, Pothoven SA, Fahnenstiel GL, Cavaletto JF, Liebig JR, Stow CA, Nalepa TF,
Madenjian CP, Bunnell DB. 2012. Seasonal zooplankton dynamics in Lake Michigan:
disentangling the impacts of top-down and bottom-up mechanisms during a critical
ecosystem transition. J. Great Lakes Res. 38: 336-352
Vollenweider, R. A., Munawar, M., and Stadelmann, P. 1974. A comparative review of
phytoplankton and primary production in the Laurentian Great Lakes. J. Fish. Res. Bd. Can.
31:739-762.
Watson, N.H. F. 1974. Zooplankton of the St. Lawrence Great Lakes - species composition,
distribution and abundance. J. Fish. Res. Board Can. 31:783-794.
Watson, N. H. F., Carpenter, G.F. 1974. Seasonal abundance of crustacean zooplankton and
net plankton biomass of lakes Huron, Erie, and Ontario. J. Fish. Res. Board Can. 31:309317.
Watson, N. H. F., Nicholson, H. F. and Culp, L. R. 1975. Chlorophyll a and primary production in
Lake Superior, May to November, 1973. Fisheries and Marine Service, Techl Rep. No. 525.
Watson, N.H.F., Wilson, J.B. 1978. Crustacean zooplankton of Lake Superior J. Great Lakes
Res., 4:481-496
Wetzel, R.G. 2001. Limnology: Lake and River Ecosystems. 3rd ed. Elsevier Academic Press.
San Diego Ca.
Yurista, P.M., Kelly, J.R., Miller, S.E. 2009. Lake Superior zooplankton biomass: Alternate
estimates from a probability-based net survey and spatially extensive LOPC surveys. J.
Great Lakes Res. 35:337-346.
117
Tables
Table 1: Locations and station depths of zooplankton survey stations in the Thunder Bay area
from 1971 to 2014, including the Ontario Ministry of Natural Resources 2005 Superior
embayment survey sites.
Station
Area
Description
Latitude Longitude
Great Lakes Biological Laboratory (1971)
47
Thunder Bay
central Thunder Bay
48
Thunder Bay
north
45
Coastal
Black Bay mouth - nearshore
46
Coastal
Thunder Bay mouth offshore
49
Coastal
south Pie Island - nearshore
50
Coastal
NW Isle Royale- offshore
Depth
48.3667
-88.9967
56
48.4300
-89.1467
30
48.3767
-88.5283
70
48.1600
-88.9250
246
48.1683
89.1800
47.9667
-89.3750
99
236
48.3017
40
48.2983
-88.9500
-89.0667
-89.1800
48.3300
-88.6333
98
48.2833
187
48.0833
-88.5972
-89.1483
-89.0950
OMOE Index suveys (1999, 2005, 2011)
283
Coastal
Flatland I. SW Thunder Bay
284
Thunder Bay
Welcome Island
285
Coastal
Sturgeon Bay
48.2133
48.3669
48.5277
-89.2631
-89.1561
-88.4455
6
15
8
OMNR Embayment Survey (2005)
TB10
Thunder Bay
S. Pie Island
TB50
Thunder Bay
S. Pie Island
TB100
Thunder Bay
S. Pie Island
NB10
Nipigon Bay
NB100
Nipigon Bay
DS10
Duluth
Knife R.
DS100
Duluth
Knife R.
AI10
Apostle Islands
AI100
Apostle Islands
48.2124
48.2042
48.1964
48.8059
48.8083
46.9177
46.9056
46.8719
46.8868
89.1560
89.1410
89.1124
87.5994
87.6132
91.8451
91.8226
90.5951
90.5776
10
5
100
10
100
10
100
10
100
Great Lakes Biological Laboratory (1973)
137
Thunder Bay
Sibley Peninsula tip
138
Thunder Bay
outer harbour mouth
139
Thunder Bay
NW Pie Island
135
Coastal
Black Bay mouth - nearshore
133
Coastal
Black Bay mouth - offshore
140
Coastal
south Pie Island - nearshore
142
Coastal
south Pie Island - offshore
118
48.3000
48.1500
27
25
220
240
Table 2: Locations and station depths (m) of USGS zooplankton survey stations along the
Canadian coast of Lake Superior, sampled between 1990 and 2014. Temperatures are the
1990 to 1992 means in C.
* indicates the location is approximate.
station
Area
Description
latitude
longitude
depth
temper.
401
402
403
406
407
408
400
404
405
410
411
412
413
414
415
416
417
450
451
453*
454
455
456
457
462
463
464
465
466
458*
459
460
461
Thunder Bay
Thunder Bay
Thunder Bay
Black Bay
Black Bay
Black Bay
W. coastal
W. coastal
W. coastal
W. coastal
W. coastal
Nipigon Bay
Nipigon Bay
Nipigon Bay
Nipigon Bay
Nipigon Bay
Nipigon Bay
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
East coastal
S coastal
S coastal
S coastal
S coastal
MacKenzie Bay
Sawyer Bay
Pie Island
George's Point
Central
Northeast
Cloud Bay
Thunder Cape
Black Bay mouth
Borden Island
Shesheeb Bay
SW Nipigon Bay
Red Rock
Dublin Creek
Rainboth Point
Sampson Island
Schreiber Channel
Michipicoten Island
Dog River
Old Woman Bay
Red Rock River Bay
Gargantua Bay
Agawa Bay
Alona Bay
Dore' Bay
The Flats
Crane Island
Otter Island
Richardson Harbor
Batchawana Bay
Maple Island
Goulais Point
Pancake Point
48.5048
48.3897
48.2538
48.4907
48.5587
48.6028
48.0729
48.3070
48.4073
48.5119
48.5993
48.8319
48.9350
48.9378
48.8802
48.8283
48.8312
47.7993
47.9241
47.7831
47.6756
47.5470
47.3102
47.1664
47.9403
47.9015
47.9397
48.1197
48.0269
46.9030
46.7637
46.6566
46.9288
-88.9316
-88.9100
-89.1787
-88.6239
-88.5788
-88.5007
-89.3992
-88.9110
-88.6888
-88.3390
-88.3059
-88.1155
-88.2244
-87.9790
-87.7642
-87.6668
-87.4759
-85.6933
-85.1784
-84.9619
-85.0007
-84.9805
-84.6670
-84.7218
-84.9456
-85.4375
-85.8202
-86.0710
-85.9960
-84.5748
-84.6250
-84.5787
-84.7284
46
80
43
43
29
20
64
65
74
41
55
51
29
30
45
117
70
88
68
70
80
110
85
130
110
80
120
100
110
46
72
62
72
12.0
12.1
7.9
12.8
12.7
15.7
4.8
6.3
10.5
5.6
8.0
13.2
13.8
12.5
9.9
9.8
6.5
2.8
2.9
2.9
2.7
3.7
3.2
3.2
3.2
3.0
3.1
3.0
7.8
6.7
6.5
119
Table 3a. 2001 Survey locations in Lake Superior 2001. Data courtesy of Environment Canada.
– indicates station was not sampled in the fall. N/A indicates Secchi readings could not be taken
because the station was visited after dark. Temp indicates epilimnetic water temperatures.
Station
Station
2
2
12
12
22
22
23
23
25
25
31
31
39
39
42
42
43
43
45
45
51
51
57
57
59
59
68
68
76
76
80
80
82
82
95
95
97
97
100
100
113
113
115
115
118
118
125
125
127
127
139
139
153
153
155
155
157
157
160
160
164
164
169
169
177
177
196
196
201
201
218
218
221
221
Latitude
Latitude
46
32 39
46
47 32
02 39
12
47
02
46 58 12
05
46
47 58
12 05
51
47
47 12
27 51
19
47
27
47 55 19
11
47
47 55
41 11
22
47
41
47 19 22
25
47
47 19
04 25
49
47
04
46 54 49
30
46
46 54
31 30
02
46
31
46 56 02
02
46
47 56
09 02
36
47
09
47 00 36
56
47
47 00
24 56
06
47
47 24
34 06
57
47
34
47 51 57
33
47
48 51
13 33
02
48
13
48 26 02
16
48
48 26
45 16
21
48
45
48 08 21
42
48
47 08
50 42
49
47
50
47 36 49
26
47
47 36
36 26
19
47
47 36
50 19
53
47
50
48 15 53
12
48
47 15
41 12
18
47
41
47 48 18
13
47
47 48
36 13
50
47
36
47 22 50
00
47
47 22
01 00
37
47
01
47 12 37
24
47
47 12
44 24
24
47
46 44
44 24
54
46
44
47 07 54
54
47
46 07
49 54
05
46
49
46 46 05
54
46 46 54
May 10-15, 2001
Aug 10-15,
17-23, 2001
May
May 10-15,
2001
Aug 17-23,
2001
Surface
Surface
Surface
Surface
Surface
Depth Secchi Temperature
Temperature
Depth Secchi Temperature
Depth
Secchi
Temperature
Longitude
(m) Latitude
(m)
(°C)
(°C)
Station
Longitude
(m) Secchi
(m)(m) Temperature
(°C)
Longitude
(m)
(m)
(°C)
Secchi
(m)
(°C)
-84 44 56 2 101.4 46 32
N/A
9
19.3
39 -84 442.6
56 101.4
N/A
2.6
-84
44
56
101.4
N/A
2.6
9
19.3
-85 06 10 12171.8 47 02812 -85 06
2.06
N/A
16.7
10 171.8
8
2.06
-85
06
10
171.8
8
2.06
N/A
16.7
-85 43 43 22159.7 46 58-05 -85 43 43
N/A
17.2
159.7
-85
43
43
159.7
N/A
17.2
-85 38 07 23135.6 47 12
N/A
16.6
51 -85 382.5
07 135.6
N/A
2.5
-85
N/A
N/A
16.6
-85 38
16 07
28 25135.6
245.9 47 27
919 -85 162.5
2.1
N/A
17.5
28 245.9
9
2.1
-85
16
28
245.9
9
2.1
N/A
17.5
-84 54 50 31100.5 47 55911 -84 542.4
10.5
17.6
50 100.5
9
2.4
-84
922 -85 582.4
10.5
17.6
-85 54
58 50
02 39100.5
133.5 47 4114
202 133.5
15
16.9
14
2
-85
58
02
133.5
14
2
15
16.9
-86 22 22 42 175 47 19
N/A
17.7
25 -86 222.6
22
175
N/A
2.6
-86
175 47 04
N/A
N/A
17.7
-86 22
28 22
44 43199.7
N/A
2.5
18.1
49 -86 282.6
44 199.7
N/A
2.5
-86
28
44
199.7
N/A
2.5
N/A
18.1
-86 35 49 45364.5 46 54
N/A
19.6
30 -86 352.7
49 364.5
N/A
2.7
-86
35
49
364.5
N/A
2.7
N/A
19.6
-87 20 15 51 18.9 46 31
N/A
8
21.1
02 -87 204.9
15
18.9
N/A
4.9
-87
20
15
18.9
N/A
4.9
8
21.1
-87 18 21 57142.3 46 561102 -87 182.1
12
20.4
21 142.3
11
2.1
-87
18
21
142.3
11
2.1
12
20.4
-87 16 55 59155.6 47 091336 -87 162.4
N/A
19.2
55 155.6
13
2.4
-87
16
55
155.6
13
2.4
N/A
19.2
-88 11 00 68145.9 47 00
N/A
11.5
19.0
56 -88 113.1
00 145.9
N/A
3.1
-88
11
00
145.9
N/A
3.1
11.5
19.0
-87 24 43 76160.4 47 241306 -87 242.1
N/A
19.2
43 160.4
13
2.1
-87
1357 -86 572.1
N/A
19.2
-86 24
57 43
05 80160.4
313.4 47 34
N/A
2.5
12
16.8
05 313.4
N/A
2.5
-86
57
05
313.4
N/A
2.5
12
16.8
-86 38 12 82247.1 47 51
N/A
16.3
33 -86 382.6
12 247.1
N/A
2.6
-86
38
12
247.1
N/A
2.6
N/A
16.3
-87 00 55 95198.7 48 13
N/A
16.0
02 -87 002.2
55 198.7
N/A
2.2
-87
00
55
198.7
N/A
2.2
N/A
16.0
-87 15 09 97151.9 48 26
11.5
7
15.6
16 -87 152.2
09 151.9
11.5
2.2
-87
15
09
151.9
11.5
2.2
7
15.6
-86 58 27 100114.3 48 45921 -86 58 227 114.3
N/A
16.9
9
2
-86
58
27
114.3
9
2
N/A
16.9
-87 42 12 113274.3 48 081242 -87 422.3
11.5
15.8
12 274.3
12
2.3
-87
1249 -87 272.3
11.5
15.8
-87 42
27 12
24 115274.3
174.3 47 50
N/A
2.1
14
16.5
24 174.3
N/A
2.1
-87
27
24
174.3
N/A
2.1
14
16.5
-87 42 34 118166.3 47 36
N/A
18.5
26 -87 422.6
34 166.3
N/A
2.6
-87
42
34
166.3
N/A
2.6
N/A
18.5
-88 13 02 125262.1 47 36
N/A
19.5
19 -88 132.4
02 262.1
N/A
2.4
-88
N/A
2.4
N/A
19.5
-88 13
20 02
12 127262.1
262.2 47 50
N/A
2.3
8
16.3
53 -88 20 12 262.2
N/A
2.3
-88
20
12
262.2
N/A
2.3
8
16.3
-89 10 47 139 45 48 15
N/A
16.8
12 -89 103.8
47
45
N/A
3.8
-89
10
47
45
N/A
3.8
N/A
16.8
-89 27 59 153161.9 47 411418 -89 272.4
11.5
17.0
59 161.9
14
2.4
-89
27
59
161.9
14
2.4
11.5
17.0
-89 08 49 155 67 47 481513 -89 082.2
N/A
17.2
49
67
15
2.2
-89
08
49
67
15
2.2
N/A
17.2
-89 00 03 157204.4 47 36
14.5
N/A
16.4
50 -89 002.4
03 204.4
14.5
2.4
-89
00
03
204.4
14.5
2.4
N/A
16.4
-88 49 07 160146.4 47 22
N/A
9
20.9
00 -88 492.8
07 146.4
N/A
2.8
-88
49
07
146.4
N/A
2.8
9
20.9
-89 02 20 164 24 47 01
N/A
8.5
20.8
37 -89 024.3
20
24
N/A
4.3
-89
02
20
24
N/A
4.3
8.5
20.8
-89 40 03 169200.4 47 121824 -89 402.6
9.5
18.6
03 200.4
18
2.6
-89
40
03
200.4
18
2.6
9.5
18.6
-90 14 30 177128.5 47 441024 -90 142.3
11
17.2
30 128.5
10
2.3
-90
11
17.2
-90 14
42 30
10 196128.5
29.1 46 4410
354 -90 422.3
7.6
8
19.9
10
29.1
3
7.6
-90
42
10
29.1
3
7.6
8
19.9
-91 06 46 201 197 47 07-54 -91 06 46
N/A
19.2
197
-91
-N/A
19.2
-91 06
53 46
04 218 197
130 46 49--05 -91 53 04
N/A
19.7
130
-91
130 46 46
-54 -92 037.9
N/A
19.7
-92 53
03 04
13 22122.3
N/A
19.6
13
22.3
N/A
7.9
-92 03 13
22.3
N/A
7.9
N/A
19.6
120
Aug 17-23, 200
Surfa
Temper
Secchi (m)
(°C
9
19.
N/A
16.
N/A
17.
N/A
16.
N/A
17.
10.5
17.
15
16.
N/A
17.
N/A
18.
N/A
19.
8
21.
12
20.
N/A
19.
11.5
19.
N/A
19.
12
16.
N/A
16.
N/A
16.
7
15.
N/A
16.
11.5
15.
14
16.
N/A
18.
N/A
19.
8
16.
N/A
16.
11.5
17.
N/A
17.
N/A
16.
9
20.
8.5
20.
9.5
18.
11
17.
8
19.
N/A
19.
N/A
19.
N/A
19.
Table 3b: 2011 CSMI survey locations in Lake Superior sampled by DFO in from 26 July 26 to
04 August (Summer) and 27 September to 03 October (Fall). – indicates station was not
sampled in the fall. N/A indicates Secchi readings could not be taken because the station was
visited after dark. Temp indicates epilimnetic water temperatures.
Station
Area
Description
Summer
Latitude Longitude Depth Secchi (m) Temp (C)
2
23
31
43
51
68
80
100
113
127
139
164
169
177
196
201
221
Coastal
Offshore
Coastal
Offshore
Coastal
Coastal
Offshore
Offshore
Offshore
Offshore
Thunder Bay
Coastal
Offshore
Coastal
Apostle Islands
Offshore
Duluth
Whitefish Bay
central east
Michipicoten ON
southeast
Marquette MI
Keweenaw Bay
central deep hole
Jackfish Bay
central
central
Thunder Bay ON
west Keweenaw Pen.
west central
NW coast
Apostle Islands South
Apostle Islands NW
Duluth
46.5433
47.2133
47.9183
47.0800
46.5167
47.0167
47.5833
48.7567
48.1450
47.8483
48.2533
47.0267
47.2067
47.7467
46.7483
47.1316
46.7817
-84.7483
-85.6333
-84.9128
-86.4778
-87.3367
-88.1833
-86.9517
-86.9758
-87.7033
-88.3367
-89.1800
-89.3383
-89.6667
-90.2350
-90.7033
-91.1116
-92.0542
121
95
126.4
91.7
192.9
17.6
145.4
312
112
275.8
266.6
44
23
201
128.8
28.8
193
21.5
N/A
11
N/A
13
N/A
13
N/A
N/A
16
N/A
N/A
N/A
N/A
8
12
N/A
N/A
19.8
12
19.8
9
19
16
9.3
16.6
9.1
11.8
15.5
18
14.1
15.5
20.5
17.6
17.8
Fall
Secchi (m) Temp (C)
9
10
12.5
N/A
12
N/A
6
8
10
2.5
16.8
13.1
12.5
13.6
15.1
11.5
12.5
11.7
9.6
10
Table 4. Physical and chemical information collected at the Thunder Bay (TB) area stations during the 1971 surveys. Sur. Temp is
the surface temperature, and TWC is the whole water column temperature averaged at 1, 5, 10, 25, 50, 100, 150 and 2 m off bottom.
TB-UF is unfiltered total phosphorus. Chemistry results are averaged for the TWC. Coast NS = coastal nearshore stations, and
Coast Off = coastal offshore stations. Station 48 inside the AOC is shown in bold.
Date
Station
Area
Secchi
(m)
Sur. Temp.
(degC)
TWC Temp NO3/NO2
(degC)
mg/L
NH3
(mg/L)
TOC
(mg/L)
DO
(mg/L)
SRP
(ug/L)
TP-UF
(ug/L)
Conduct.
(useimens)
turbidity
(FTU)
(units)
2-Jun-71
47
TB
5
4
3.9
0.267
0.008
2.00
13.0
0.30
6.00
100
3.50
2-Jun-71
48
TB
1.5
8.6
2-Jun-71
49
Coast NS
4.5
3.4
8.6
0.209
0.014
4.17
12.4
0.30
7.68
96
11.88
3.5
0.262
0.007
2.17
13.2
0.30
3.32
100
8.13
30-May-71
45
Coast NS
7
31-May-71
46
Coast Off
10
2.7
3.1
0.272
0.010
1.87
13.6
0.30
2.55
99
0.42
2.4
2.5
0.271
0.007
1.93
13.4
0.53
3.25
98
0.36
2-Jun-71
50
Coast Off
-
2.2
2.5
0.280
0.013
1.07
13.5
0.85
2.76
97
0.55
7-Jul-71
47
TB
4
14
7.5
0.202
0.007
2.37
11.7
0.58
6.60
97
0.45
7-Jul-71
48
TB
4
15.1
15.1
0.194
0.005
3.13
11.4
0.30
7.58
101
0.45
7-Jul-71
49
Coast NS
5
6.9
5.1
0.244
0.008
1.63
12.9
0.55
3.46
98
0.27
5-Jul-71
45
Coast NS
-
7.1
5.7
0.211
0.007
2.17
13.3
0.66
3.64
100
0.20
5-Jul-71
46
Coast Off
7
3.6
3.5
0.251
0.004
2.30
13.3
0.30
4.78
95
0.24
7-Jul-71
50
Coast Off
-
3.5
3.6
0.253
0.002
1.87
13.2
0.30
4.54
97
0.40
11-Oct-71
47
TB
-
10.8
8.4
0.238
0.002
1.90
10.9
0.30
2.78
98
0.50
11-Oct-71
48
TB
5
10.9
9.0
0.259
0.003
1.75
10.7
0.46
3.28
100
0.90
11-Oct-71
49
Coast NS
-
10.8
7.8
0.255
0.005
1.83
11.4
0.36
2.94
98
0.49
11-Oct-71
45
Coast NS
-
11
7.8
0.257
0.004
1.60
11.5
0.36
2.21
98
0.24
11-Oct-71
46
Coast Off
-
10.2
5.3
0.264
0.004
1.30
12.0
0.48
1.91
97
0.34
11-Oct-71
50
Coast Off
6
10.4
5.6
0.252
0.003
1.87
11.8
0.42
4.43
96
0.36
122
Table 5. Physical and chemical information collected at the Thunder Bay (TB) area stations
during the 1973 surveys. Sur. Temp is the surface temperature, and TWC is the whole water
column temperature averaged at 1, 5, 10, 25, 50, 100, 150 and 2 m off bottom. TP-UF is
unfiltered total phosphorus. Chemistry results are averaged for the TWC. Coast NS = coastal
nearshore stations, and Coast Off = coastal offshore stations. Station 139 inside the AOC is
shown in bold.
Date
Station
Area
Secchi
(m)
Sur. Temp.
(degC)
TWC Temp Chlor. a NO3/NO2
(degC)
(ug/L)
mg/L
NH3
(mg/L)
DO
(mg/L)
SRP
(ug/L)
TP-UF
(ug/L)
Conduct.
(useimens)
turbidity
(FTU)
(units)
19-May-73
137
TB
-
2.5
2.7
1.3
19-May-73
138
TB
-
-
-
1.7
0.32
0.003
13.6
-
-
-
0.36
0.31
0.003
13.4
-
-
-
19-May-73
139
TB
-
-
-
0.35
1.7
0.29
0.004
13.2
-
-
-
19-May-73
135
Coast NS
-
2.2
0.53
2.0
0.8
0.33
0.004
13.7
-
-
-
19-May-73
133
Coast Off
-
0.24
2.1
2.1
0.9
0.33
0.004
13.6
-
-
98
19-May-73
140
Coast NS
0.23
8.0
2.2
2.0
0.9
0.33
0.004
13.7
-
-
-
19-May-73
142
Coast Off
0.20
14.0
2.0
1.8
0.9
0.33
0.003
13.7
-
-
-
0.20
24-Jun-73
137
TB
-
8.7
6.9
1.2
0.26
0.005
12.9
-
-
-
0.42
19-May-73
138
TB
5.0
9.4
8.1
1.7
0.26
0.008
12.3
-
-
-
0.43
19-May-73
139
TB
-
-
-
2.1
0.25
0.005
11.9
-
-
-
0.48
22-Jun-73
135
Coast NS
9.0
3.5
3.6
-
0.28
0.004
13.7
-
-
-
0.24
22-Jun-73
133
Coast Off
12.0
3.2
3.2
1.0
0.28
0.004
13.8
-
-
95
0.24
22-Jun-73
140
Coast NS
14.0
3.2
3.2
0.9
0.29
0.007
13.5
-
-
-
0.20
22-Jun-73
142
Coast Off
13.0
3.0
3.1
0.9
0.29
0.007
13.5
-
-
-
0.24
2-Aug-73
137
TB
5.0
16.7
10.9
1.6
0.25
0.006
11.7
1.14
4.63
-
0.64
3-Aug-73
138
TB
5.0
11.5
7.9
2.2
0.26
0.010
12.1
1.22
5.30
-
0.48
3-Aug-73
139
TB
5.0
16.8
11.3
1.4
0.25
0.009
11.6
1.64
5.77
-
0.56
2-Aug-73
133
Coast NS
8.0
11.5
5.9
1.3
0.28
0.005
13.0
1.26
3.10
92
0.23
2-Aug-73
135
Coast Off
7.0
11.8
8.9
1.5
0.27
0.007
12.4
1.28
4.53
-
0.24
3-Aug-73
140
Coast NS
4.5
14.7
9.8
1.6
0.26
0.004
12.1
0.94
4.87
-
0.48
3-Aug-73
142
Coast Off
6.5
15.8
10.1
1.8
0.26
0.006
12.2
1.20
6.10
-
0.36
12-Sep-73
137
TB
6.0
13.5
8.2
1.0
0.27
0.008
12.2
-
-
-
0.40
13-Sep-73
138
TB
4.0
15.8
11.3
1.3
0.26
0.008
11.1
-
-
-
0.34
13-Sep-73
139
TB
5.0
12.6
9.9
1.3
0.27
0.006
11.7
-
-
-
0.58
12-Sep-73
133
Coast NS
6.0
14.3
7.2
1.7
0.28
0.005
12.3
-
-
91
0.30
12-Sep-73
135
Coast Off
4.5
11.0
8.3
1.1
0.28
0.007
12.4
-
-
-
0.56
13-Sep-73
140
Coast NS
-
11.8
9.3
1.3
0.27
0.012
11.7
-
-
-
0.28
13-Sep-73
142
Coast Off
-
14.0
9.8
1.6
0.26
0.011
11.7
-
-
-
0.30
22-Oct-73
137
TB
-
8.0
7.2
1.2
0.28
0.008
11.8
1.80
7.37
-
0.55
22-Oct-73
138
TB
6.0
8.5
7.8
1.4
0.28
0.007
11.6
1.38
7.23
-
0.68
22-Oct-73
139
TB
5.0
7.4
7.4
1.3
0.28
0.005
12.0
0.98
6.20
-
0.53
22-Oct-73
133
Coast NS
-
8.5
6.4
1.5
0.29
0.005
12.4
0.87
3.99
91
0.44
22-Oct-73
135
Coast Off
-
7.9
7.3
1.5
0.28
0.006
12.1
1.08
5.75
-
0.45
22-Oct-73
140
Coast NS
9.0
7.9
7.3
1.7
0.28
0.003
12.2
0.90
5.17
-
0.35
22-Oct-73
142
Coast Off
9.0
8.1
7.5
1.7
0.28
0.003
12.0
0.60
5.13
-
0.33
24-Nov-73
137
TB
5.0
4.5
4.3
1.6
0.29
0.006
12.3
0.57
5.75
-
0.73
24-Nov-73
138
TB
7.5
5.0
4.9
1.2
0.28
0.006
12.2
1.50
7.33
-
1.00
24-Nov-73
139
TB
4.0
4.5
4.3
1.5
0.28
0.006
12.3
1.33
6.53
-
0.57
24-Nov-73
133
Coast NS
-
5.2
4.9
1.2
0.29
0.003
12.4
1.08
4.38
89
0.28
24-Nov-73
135
Coast Off
6.0
5.3
5.2
1.2
0.29
0.004
12.3
0.43
5.37
-
0.33
25-Nov-73
140
Coast NS
10.0
4.5
4.9
0.9
0.29
0.005
12.4
1.00
4.80
-
0.20
25-Nov-73
142
Coast Off
10.0
4.9
4.8
0.9
0.29
0.003
12.4
0.73
6.60
-
0.30
123
Table 6. Physical and chemical information collected at embayment stations by the OMNR
during the 2005 surveys. TWC is the total water column, and unstr. indicates unstratified
conditions. * indicates that no clear epilimnion was present. The mesh column indicates whether
a zooplankton sample was counted, and the net mesh size used.
mesh
temperature (C)
Conductivity
Station
Date
(um)
Secchi
Depth (m)
surface
TWC
pH
Bottom
epi (m)
Bottom
meta (m)
AI10
AI50
AI100
19-Jul-05
19-Jul-05
19-Jul-05
64
153
-
10.2
10.9
11.9
15.9
16.5
16.7
13.5
8.7
9.2
8.2
8.2
8.1
94.2
94.5
94.1
unstr.
3
15
unstr.
22
20
AI10
AI50
AI100
07-Sep-05
07-Sep-05
07-Sep-05
153
153
10.0
11.8
17.9
17.9
17.2
17.8
10.7
10.6
8.4
8.3
8.2
96.4
96.4
96.1
unstr.
11
16
unstr.
33
31
AI10
AI50
AI100
26-Oct-05
26-Oct-05
26-Oct-05
153
153
9.0
10.1
10.0
10.1
10.1
9.6
9.6
8.4
8.4
8.5
92.4
92.4
92.4
unstr.
40.0
40.0
unstr.
>49
>49
DS10
DS50
DS100
21-Jun-05
21-Jun-05
21-Jun-05
153
153
-
5.2
8.5
7.7
7.3
6.8
7.9
6.2
4.7
4.6
8.0
7.9
7.9
90.7
90.5
92.3
unstr.
6
6
unstr.
8
10
DS10
DS50
DS100
15-Aug-05
15-Aug-05
15-Aug-05
-
12.7
13.5
11.1
5.8
7.8
10.1
5.4
5.2
5.6
7.6
7.8
7.9
90.6
91.6
92.4
unstr.
2
2
unstr.
9
7
DS10
DS50
DS100
06-Sep-05
06-Sep-05
06-Sep-05
64
153
12.0
12.5
12.1
12.9
13.2
13.1
12.4
8.4
8.3
8.2
8.2
8.2
93.3
93.4
93.3
unstr.
8
10
unstr.
22
27
DS10
DS50
DS100
27-Sep-05
27-Sep-05
27-Sep-05
64
153
-
12.5
13.0
13.8
-
-
-
-
-
-
NB10
NB50
NB100
06-Jun-05
06-Jun-05
06-Jun-05
153
153
-
8.8
8.4
9.2
5.0
4.7
4.4
5.0
4.7
4.2
7.8
7.8
7.8
91.4
90.9
92.7
unstr.
unstr.
unstr.
unstr.
unstr.
unstr.
NB10
NB50
NB100
08-Aug-05
08-Aug-05
08-Aug-05
64
153
-
5.6
6.1
6.3
19.0
18.8
18.5
17.2
11.1
10.1
8.2
8.3
8.3
105.9
106.1
105.2
unstr.
4
9
unstr.
21
15
NB10
NB50
NB100
18-Oct-05
18-Oct-05
18-Oct-05
64
64
6.5
6.0
13.2
13.2
13.1
13.2
10.0
10.1
8.5
8.4
8.4
97.8
98.2
98.3
unstr.
22
22
unstr.
26
31
TB10
TB50
TB100
30-May-05
30-May-05
30-May-05
153
153
153
9.8
11.3
16.8
5.0
3.6
3.1
4.6
3.8
3.0
7.7
7.7
7.7
90.6
90.1
89.7
unstr.
unstr.
unstr.
unstr.
unstr.
unstr.
TB10
TB50
TB100
13-Jul-05
13-Jul-05
13-Jul-05
-
7.4
7.2
8.0
17.9
15.7
16.4
11.8
8.2
8.3
8.2
8.2
8.3
99.7
99.6
98.8
2
*
*
4
11
22
TB10
TB50
TB100
25-Jul-05
25-Jul-05
25-Jul-05
-
8.9
9.6
9.1
14.4
15.3
16.5
13.0
8.8
8.3
8.2
8.1
8.1
96.3
96.7
97.4
unstr.
3
6
unstr.
9
21
TB10
TB50
TB100
05-Aug-05
05-Aug-05
05-Aug-05
64
64
-
8.6
8.7
8.9
17.2
17.5
16.8
16.2
9.5
8.7
8.2
8.3
8.2
99.0
98.7
98.1
2
2
9
5
25
18
TB10
TB50
TB100
12-Sep-05
12-Sep-05
12-Sep-05
-
8.7
8.5
12.6
14.7
12.4
11.1
11.1
7.2
5.4
8.2
8.1
8.1
96.4
95.9
94.6
unstr.
*
*
unstr.
14
9
TB10
TB50
TB100
22-Sep-05
22-Sep-05
22-Sep-05
-
-
16.3
16.2
16.3
16.3
15.3
15.2
8.3
8.3
8.2
94.4
94.4
94.5
unstr.
28
22
unstr.
43
24
TB10
TB50
TB100
03-Oct-05
03-Oct-05
03-Oct-05
-
10.9
10.9
11.5
14.8
14.7
14.7
14.2
8.3
8.8
8.4
8.4
8.4
94.4
94.4
94.4
3
4
17
4
22
20
TB10
TB50
TB100
11-Oct-05
11-Oct-05
11-Oct-05
153
153
153
10.8
10.8
10.3
13.8
13.9
13.9
13.8
13.5
13.2
8.3
8.3
8.3
93.8
94.0
94.1
unstr.
37
23
unstr.
43
27
(usiem.cm -1 )
124
Table 7. Physical and chemical information collected at the Thunder Bay (TB) area stations by the OMOE during the 2005 surveys.
Chlor A is total chlorophyll a, TP is total phosphorus and DOC is dissolved organic carbon.
Secchi
DOC
-1
Chlor. A Conductivity NH3+NH4 NO3/NO2
-1
date
station
14-May-05
283
16-May-05
284
14-May-05
285
(m)
1.3
1.3
3.0
(mg.L )
4.37
2.57
1.80
ug.L
3.80
2.17
1.60
18-Aug-05
18-Aug-05
17-Aug-05
283
284
285
4.0
6.0
4.8
1.77
1.67
1.53
2.07
1.43
0.80
6-Oct-05
6-Oct-05
8-Oct-05
283
284
285
1.2
4.5
4.0
1.90
1.53
1.40
1.93
1.63
1.47
usiem.cm
110
102
94
-1
-1
mg.L
0.0063
0.0093
0.0043
mg.L
0.2897
0.3290
0.3080
104
102
101
0.0020
0.0020
0.0143
103
98
98
0.0090
0.0073
0.0020
125
pH
-1
TP
Turbidity
-1
7.89
7.87
7.95
ug.L
23.3
15.0
12.3
FTU
5.42
3.95
0.77
0.2947
0.2920
0.2743
7.76
7.77
7.97
5.7
3.0
7.3
0.84
0.52
1.08
0.2907
0.3053
0.2883
8.02
8.05
8.05
11.7
2.7
2.3
6.09
0.86
0.90
Table 8. Seasonal changes in phytoplankton biomass (mg m-3) at station 139 Thunder Bay,
Lake Superior, 1973 (Munawar and Munawar 1978).
Cyanophyta
Chroococcus dispersus var. minor G.M. Smith
spores
Oscillatoria limnetica Lemmermann
Oscillatoria sp.
Chlorophyta
Ankistrodesmus falcatus (Corda) Ralfs
Carteria sp. (Carter) Diesing
cysts
Chlamydomonas metapyrenigera Skuja
Chlorella sp.
Scenedesmus bijuga (Turpin) Lagerh.
Chrysophyceae
Chromulina sp. Cienkowski
Chrysochromulina parva Lackey
Dinobryon bavaricum Imhof
Dinobryon sp.
Dinobryon divergens Imhof
Ochromonas sphagnalis Conrad
Ochromonas sp. Wyssotzki
Stelexomonas sp.
Diatomeae
May
Jun
Jul/Aug
Sep
Oct
Nov/Dec
0.47
1.08
0.25
0.25
0.82
0.90
0.28
0.97
4.15
0.12
1.15
0.67
1.95
Asterionella formosa Hassall
Asterionella gracillima (Hantzsch) Heiberg
Cyclotella comta (Ehr.) Kütz.
Cyclotella glomerata Bachmann
Cyclotella stelligera (Cleve & Grunow) Van Heurck
Fragilaria crotonensis Kitton
Rhizosolenia eriensis H.L. Smith
Synedra acus var. radians (Kütz.) Hustedt
Synedra maria
Synedra sp.
Tabellaria fenestrata (Lyngb.) Kütz.
Cryptophyceae
Cryptomonas erosa Ehrenberg
Cryptomonas marssonii Skuja
Katablepharis ovalis Skuja
Rhodomonas minuta Skuja
Rhodomonas minuta var. nannoplanctica Skuja
2.28
4.43
1.98
0.64
0.90
0.96
1.12
0.36
0.09
6.16
2.82
3.28
5.56
0.19
2.45
2.13
6.27
1.21
6.70 69.46
2.66
22.07
0.36
39.20
3.95
2.61
5.17
7.45
0.35
18.07 2.63
64.36
10.15
8.78
4.60
19.14
6.72
0.24
1.46
18.52
0.94
1.70
39.64
1.23
2.02
0.82
0.90
23.06 14.97
13.69
10.01
1.51 7.91
23.83 45.00
126
11.41
12.08
4.52
42.69
3.46
10.11 9.82
17.33
0.93
39.87 27.96
3.80 1.54
1.90
32.80
3.83
Table 9. Seasonal changes in phytoplankton biomass (mg m-3) at station 139 Thunder Bay, Lake Superior, 2001.
May
Cyanophyta
Anabaena flos-aquae
Aphanocapsa delicatissima West & West
Chroococcus dispersus var. minor G.M. Smith
Gomphosphaeria lacustris Chodat
Merismopedia sp.
Oscillatoria limnetica Lemmermann
Oscillatoria sp.
Chlorophyta
Ankistrodemus falcatus var. acicularis (A. Braun) G.S. West
Ankistrodesmus falcatus (Corda) Ralfs
Ankistrodesmus falcatus var. mirabilis (West & West) G.S. West
Ankistrodesmus falcatus var. spirilliformis G.S. West
Chlamydomonas globosa Snow
Chlamydomonas sp.
Chlorella homosphaera Skuja
Chlorella vulgaris Beyerinck
Cosmarium phaseolus Brebisson
Dictyosphaerium cells
Dictyosphaerium pulchellum Wood
Elakatothrix gelatinosa Wille
Gemellicystis neglecta
Gloeocystis cyst
Gloeocystis gigas (Kuetz.) Lagerheim
Gloeocystis planctonica (West & West) Lemmermann
Gloeocystis sp.
Green cells
Kirchneriella lunaris (Kirch.) Moebius
Oocystis gloeocystiformis Borge
Oocystis lacustris Chodat
Oocystis parva West & West
Oocystis submarina Lagerheim
Pedinomonas minutissima Skuja
Quadrigula lacustris (Chod.) G.M. Smith
Scenedesmus bijuga (Turp.) Lagerheim
Tetraedron minumun cyst
Tetraedron minumun var. tetralobulatum Reinsch
Tetrastrum sp.
Chrysophyceae
Chromulina mikroplankton Pascher
Chromulina minima Dolf.
Chromulina obconica
Chromulina sp.
Chromulina sphaerica Doflein
7.27
21.36
2.63
1.51
9.47
0.17
0.18
1.87
0.40
7.28
13.61
17.44
August
2.64
0.36
6.30
2.34
2.22
0.03
0.02
3.20
0.99
5.64
3.39
1.92
11.67
0.43
0.31
17.12
4.68
4.88
1.35
7.17
71.99
0.53
0.25
3.50
1.43
0.38
6.97
0.75
1.15
0.96
2.76
21.75
16.66
3.22
0.34
1.61
0.33
5.88
1.43
127
May
Chrysophyceae (cont.)
Chromulina sphaeridia
Chrysamoeba sp.
Chrysidalis peritaphrena Schiller
Chrysochromulina parva Lackey
Chrysococcus sp.
Chrysolykos planctonicus Mach
Chrysomonad cells cyst
Chrysomonad flagellate D
Chrysomonad sp.
Chrysosphaera sp.
Diceras chodatii Reverdin
Dinobryon bavaricum Imhof
Dinobryon cylindricum alpinum
Dinobryon cylindricum Imhof
Dinobryon divergens cyst
Dinobryon divergens Imhof
Dinobryon sociale Ehrenberg
Dinobryon sociale var stipitatum (Stein) Lemmermann
Dinobryon sp.
Dinobryon sp.
Erkenia subaequiciliata Skuja
Kephyrion boreale
Mallomonas bispinosa
Mallomonas denticulatus
Mallomonas genevensis
Mallomonas globosa Schiller
Mallomonas Heimii
Mallomonas Hirsuta
Mallomonas horrida
Mallomonas lata Conrad
Mallomonas radiata
Mallomonas sp.
Monas sp.
Monochrysis parva
Ochromonas elegans Doflein
Ochromonas nana Doflein
Ochromonas scintillans Conrad
Ochromonas silvarum Doflein
Ochromonas sp.
Ochromonas sphagnalis Conrad
Pseudokephryion depressum Schmid
Pseudokephryion sp.
Pseudokephyrion poculum Conrad
August
71.35
8.76
1.56
0.85
12.26
28.40
0.15
63.85
8.46
1.09
58.27
4.38
0.80
1.55
1.85
7.18
6.97
185.03
0.59
18.88
0.59
9.03
1.48
19.46
8.65
0.59
0.15
33.56
1.77
10.55
4.92
1.17
1.87
3.18
39.36
1.04
24.94
4.59
1.70
31.83
25.70
2.00
0.40
1.26
3.10
42.39
0.10
4.99
0.90
5.43
4.50
1.88
0.50
Table 9. continued.
May
Chrysophyceae (cont.)
Rhizochrysis sp.
Salpingoeca frequentissima (Zacharias) Lemmermann
Sphaleromantis tetragona
Stelexmonas dichotoma Lackey
Stelexmonas sp.
Stichogloea sp.
Synura sp.
Diatomeae
Asterionella formosa Hassall
Asterionella gracillima (Hantzsch) Heiberg
Cyclotella atomus Hustedt
Cyclotella bodanica Eulenstein
Cyclotella comta (Ehr.) Kütz.
Cyclotella glomerata Bachmann
Cyclotella michiganiana
Cyclotella ocellata Pantocsek
Cyclotella pseudostelligera
Cyclotella sp.
Cyclotella stelligera (Cleve.) Grunow
Cymbella ventricosa Kuetzing
Diatoma elongatum (Lyngb.) Agardh
Fragilaria capucina Desmazieres
Fragilaria crotonensis Kitton
Fragilaria sp.
Gomphonema sp.
Melosira islandica O. Muller
Navicula exigua (Greg.) O. Muller
Navicula sp.
Nitzschia acicularis (Küetz.) W. Smith
Nitzschia gracilis Hantzsch
Nitzschia sp.
Nitzschia vermicularis (Kuetz.) Grunow
Rhizosolenia eriensis H.L. Smith
Rhizosolenia gracilis H. L. Sm.
Stephanodiscus astraea var. minutula (Küetz.) Grunow
Synedra acus Küetzing
Synedra acus var. radians (Küetz.) Hustedt
Synedra sp.
Tabellaria fenestrata (Lyngb.) Küetzing
Tabellaria flocculosa (Roth) Küetzing
August
May
2.11
0.54
0.29
6.93
19.80
6.59
1.67
820.68
92.13
19.98
13.04
45.36
27.22
27.35
9.27
9.64
35.71
30.94
9.87
4.85
1.42
6.48
24.24
5.43
1.57
5.59
40.88
10.88
2.98
154.98
2.22
0.71
40.25
1.33
2.15
1.21
0.75
0.50
2.10
0.46
0.39
43.47
1.19
1.88
2.16
1561.14
597.63
128
Cryptophyceae
Chroomonas acuta Utermöhl
Chroomonas breviciliata Nygaard
Chroomonas minor
Chroomonas Nordstedtii Hansgirg
Cryptaulax rhomboidia Skuja
Cryptomonas caudata Schiller
Cryptomonas cyst
Cryptomonas erosa cyst
Cryptomonas erosa Ehrenberg
Cryptomonas gracillis
Cryptomonas Marssonii Skuja
Cryptomonas ovata Ehrenberg
Cryptomonas pusilla
Cryptomonas reflexa cyst
Cryptomonas sp.
Cryptomonas sp. cyst
Cryptomonas tetrapyrenoidosa Skuja
Katablepharis ovalis Skuja.
Rhodomonas lens Pascher & Ruttner
Rhodomonas minuta Skuja
Rhodomonas minuta var. nannoplanctica Skuja
Rhodomonas sp.
Dinophyceae
Amphidinium luteum
Ceratium hirundinella (O.F. Muell.) Schrank
Dinoflagellate cyst
Glenodinium bogoriense
Glenodinium cyst
Glenodinium pulvisculus (Ehr.) Stein
Gymnodinium albulum
Gymnodinium cyst
Gymnodinium helveticum Penard
Gymnodinium lacustre Schiller
Gymnodinium ordinatum Skuja
Gymnodinium profundum Schiller
Gymnodinium sp.
Gymnodinium uberrimum (Allman) Kofoid & Swezy
Gymnodinium uberrimum cyst
Gymnodinium varians Maskell
Peridinium sp.
August
0.48
12.85
10.92
5.95
8.99
8.19
4.92
0.64
11.32
0.48
4.50
0.25
3.68
15.48
1.38
3.51
10.88
1.13
23.57
3.79
7.96
10.14
3.61
17.98
6.12
0.25
0.63
2.15
44.95
8.44
0.69
24.61
11.59
5.23
29.68
21.04
21.90
5.40
28.07
11.88
17.32
22.01
5.95
1.26
4.64
1.31
2.73
6.80
6.50
27.86
9.05
Table 10. Time series of Phytoplankton biomass (mg m-3) at OMOE index stations near Thunder Bay 1999, 2005, 2011.
Total Biomass mg m-3 165.7 58.2 31.7 307.7 193.9 187.2 283.7 417.7 192.1 71.7 88.3 74.6 150.4 115.4 126.4
Cyanophyta
Achnanthidium sp.
1.4
Anabaena flos aquae Br.ex Born. Flah.
Anabaena lemmermannii Rich
1.3
16.3
0.6
Anabaena sp.
0.7
Aphanocapsa elachista
0.1
0.1
Aphanocapsa holsatica ( Lemm) Cronb & Kom.
0.1
0.2
0
Aphanocapsa incerta ( Lemm) Cronb. & Kom.
0.8
Aphanocapsa sp.
6
Aphanotheca sp.
47.2
Aphanothece sp.
Chroococcus minutus ( Kutz) Naeg.
0.2
Coelosphaerium kuetzingianum Naegeli
4.4
Cyanodictyon planctonicum B.Meyer
0.3
Cyanodictyon reticulatum (Lemmermann) Geitler
Gloeocapsa sp.
Limnothrix sp.
3.7
0.4
Merismopedia punctata Meyen
0.1
Planktolyngbya limnetica Komárková-Legnerová & Cronberg
0.1
2.4
0.1
Planktolyngbya sp.
0.5
Pseudanabaena contorta Kling & Watson
0.3
0.5
0.4
0.3
0.6
Pseudanabaena limentica (Lemmermann) Komárek
0.1
0.1
0.1
0.1
0.2
Pseudanabaena sp.
1.2
0.1 0.3
0
0.5
0.2
Radiococcus Geminata
0.1
Snowella sp.
Synechococcus sp.
0.1 0.1
0.3
0.1
0.1
0.1
2
Woronichinia compacta (Lemmermann) Komárek & Hindák
0.3
0.1
0.3
Unknown Cyanophyceae
2.2
2.6 12.7
6.7
5.8 12.7
25 3.6 3.6
37.6
11
9
Chlorophyta
Actinastrum hantzschii Lagerh.
0.9
Ankistrodesmus falcatus
0
0 0.2
0.2
0.1
0
0.2
0.1
0.2
0
Botryococcus braunii
Botryococcus pila
0.3
0.3
Chlamydomonas sp.
1.4
0.8
0.8
0.1
Closterium aciculare T. West
2.6
Closterium acutum Breb
0.1
Closterium limneticum Lemmermann
0.5
1.8
Collodictyon triciliatum H. Carter
12.8
Cosmarium abbreviatum Reciborski
0.1
Cosmarium sp.
0.6
Crucigeniella pulchra
Crucigeniella quadrata (Morren) Gaillon
0 0.3
0.3
0.3
Crucigeniella tetrapedia
0.1
0.3
Dictyosphaerium sp.
2.2
Didymocystis sp.
0.1
Elakatothrix genevensis (Reverd.) Hindak
0
0.1
1.8
0.4
Elakatothrix sp.
129
fall
spring
summer
2011
fall
spring
fall
summer
spring
85 101.1
summer
Welcome Island
2005
1999
fall
summer
spring
fall
Sturgeon Bay
2005
2011
summer
spring
1999
fall
summer
2011
spring
fall
spring
fall
summer
spring
summer
Flatland Island
2005
1999
35 134.2 232.6 122.9 123.9 90.5 279.6
0.6
20.3
2.6
1.8
0.2
0.4
0.6
0
0.2
1.3
3.3
1
2
0.3
0.1
1
0.1
0.2
1
0.1
0.1
0
2.1
5.4
26
0
4.5
0.1 0.1
0.1
0.1
0.4
0.1
0.1
0
21
0.4
0.9
0.3
0.2
0.4
5.6
10.6
2.6
0
0.3
0
0.3
0.2
9.2
0.4
0.1
0.3
3.5
0.2
0.6
0
0
Table 10: continued
fall
spring
summer
2011
fall
summer
fall
summer
spring
spring
Welcome Island
2005
1999
fall
summer
spring
spring
fall
Sturgeon Bay
2005
2011
summer
1999
fall
spring
summer
2011
fall
spring
fall
summer
spring
Chlorophyta cont.
Elakatothrix sp.
Franceia sp.
Gloeotila pelagica (Nyegaard) Skuja
Koliella sp.
Lagerheimia subsalsa Lemmermann
Monoraphidium arcuatum (Korshikov) Hindák
Monoraphidium contortum (Thurs.) Kom
Monoraphidium griffithii (M. J. Berkeley) Komarkova-legn.
Monoraphidium komarkova
Monoraphidium minutum (Nägeli) Komárková-legnerová
Monoraphidium sp.
Mougeotia sp.
Nephrochlamy subsolitaria ( G.S.West) Korsh.
Nephrocytium agardhianum Naegeli
Nephroselmis sp.
Oocystis apiculata (Skuja) Kom.
Oocystis lacustris Chodat
Oocystis solitaria Wittrock
Oocystis sp.
Oocystis submarina Lagerheim
Paulschulzia pseudovolvox
Pseudosphaerocystis lacustris
Quadrigula closterioides (Bohlin) Printz
Quadrigula sp.
Scenedesmus sp.
Spermatozopsis exsultans Korshikov
Stichococcus sp.
Tetraëdron minimum (A. Br.) Hansg.
Tetraëdron minimum var. tetralobulatum Reinsch.
Unknown Chlorophyceae
Chrysophyceae
Bitrichia chodatii
Bitrichia longispina
Chrysochromulina parva
Chrysococcus sp.
Chrysoikos skuja
Chrysolykos planktonicus Mack
Dinobryon attenuatum Hilliard
Dinobryon bavaricum Imhof
Dinobryon bavaricum var. vanhoeffenii (Bachmann) Krieger
Dinobryon crenulatum West and West
Dinobryon cylindricum Imhof
Dinobryon dilalatum
Dinobryon divergens Imhof
Dinobryon pediforme (Lemm.) Steinecke
Dinobryon sertularia Ehrenberg
Dinobryon sociale Ehrenberg
summer
Flatland Island
2005
1999
0
1.2
1.9
0.8
0.1
0.4
0.2
0
0.1
0.2
0.3
0
0.1
0.1
0.1
0.1
0.6
0.2
0.1
0
0.4
0.1
0.2
0.1
0.3
0.2
0.1
0.5
1
0.3
2.2
0.1
0.5
0.8
0.6
0.1
0.4
1.5
0.7
2.4
1.8
0.5
0.2
0.3
2.8
5.5
0.2
2.6
0.2
0
0.6
0.1
0
0.2
0.7
4
0.7
0.2
0
0.3
31.7
2.5
9.2
0
0.7
16.4
0
0.2
3.2
2.2
5.2
11.5
0.3
0.4
19.5
2.4
0.3
0
0.4
5
0.6
0.1
0.7
1.9
0.1
0.4
0.2
1
1
0.1
0.1
0.4
2.8
12.6
0.1
8.1
4.8
10.6
0.4
2.5
2.8
0.3
0.1
8.6
0.8
2
1.1
5
0.1
0.5
2.3
1.4
0.1
4.1
0.2
0.9
0.1
1.6
0.3
0.5
0.5
3.6
0.7
1.7
0.6
0.8
0.3
0.2
0.4
0.1
2.8
0.1
0.1
0.1
0.9
0
12.8
0.5
0.5
0.2
0.3
3.5
6.3
0.4
0.1
0.4
0
1.7
0.3
1.2
0.2
0.5
0
0
0.5
0.1
25.1
3.3
5.4
1.6
5.4
0.8
3.1
9
0
1.6
1.2
130
9.9
7.9
0.1
0.4
0.4
11.5
1.2
8.5
0
0.2
0.1
0
0.7
0.1
6.1
0.7
0.1
1.5
0.2
0.1
0.1
0.1
0.1
2
0.2
40.3
0.5
0.6
0.2
0.2
0.7
1.1
10.8
0.5
0.1
0.9
3.8
4.9
0.1
5.5
0.3
0.2
0.2
0.3
10.2
38.1
Table 10: continued
5.5
0.8
14.9
0.2
1.2
0.1
0
0.4
0.2
0.8
5.5
fall
summer
2011
spring
fall
summer
fall
summer
spring
spring
Welcome Island
2005
1999
fall
summer
spring
spring
0.2
6.6
fall
Sturgeon Bay
2005
2011
summer
1999
fall
spring
summer
2011
fall
spring
fall
summer
spring
Chrysophyceae cont.
Dinobryon sociale var. americanum (Brunthaler) Bachmann
Dinobryon sociale var. stipitatum (Stein) Lemmermann
Dinobryon sp.
Dinobryon suecicum Lemmermann
Kephyrion boreale Skuja
Mallomonas caudata Iwanoff
Mallomonas elongatum Reverdin
Mallomonas sp.
Ochromonas sp.
Pseudokephryion sp.
Pseudokephyrion alaskanum Hilliard
Pseudopedinella sp.
Rhizochrysis limnetica G.M. Smith
Salpingoeca frequentissima (Zacharias) Lemmermann
Spiniferomonas sp.
Stelexomonas dichotoma Lackey
Stichogloea doederleinii (Schmidle) Wille
Synura sp.
Unknown Chrysophyceae
Diatomeae
Achnanthidium minutissimum
Amphipleura pelucida
Asterionella formosa
Aulacoseira ambigua
Aulacoseira granulata
Aulacoseira islandica
Aulacoseira sp.
Aulacoseira subarctica
Cocconeis sp.
Cyclotella bodanica Eulenstein
Cyclotella sp.
Cymatopleura solea (Bréb. & Godey) W. Smith
Diatoma tenue C. Agardh
Diatoma tenue var. elongatum Lyngb.
Diatoma vulgare Bory
Encyonema sp.
Fragilaria capucina Desmazières
Fragilaria crotonensis Kitton
Fragilaria pinnata Ehrenberg
Fragilaria sp.
Gyrosigma sp.
Melosira varians C.A. Agardh.
Navicula radiosa Kütz.
Navicula sp.
Nitzschia acicularis (Kütz) W. Smith
Nitzschia palea (Kütz.) W. Smith
Nitzschia sigmoidea (Nitzsch) W. Sm.
summer
Flatland Island
2005
1999
0
0.8
9
3.3
3.6
1.4
1.9
1.4
2.8 33.3
9.1
1.1
1.1
0.1 0.7
2.5 39.2
0.1
0.1
11.9
7.4
0.5
1.4
2.3 10.4
1.5
0.3
3.4 70.1
2.2
1.1 35.1 14.8
4.4
0.5
5.4
2.8
0.8
1.2
5.4
175
4.9
2.8
0.1
1.1
4.4
9.4
0.7
2.2
5.4
3.2
4.5
0.9
9
2.1
0.3
0.3
3.1
26.2
0.8
0.8
1.2
10.5
9.3
0.7
2.5
0.4
8.7
1
2.9 14.8
5
0.2
4.2
5.4
1.1
4.3
0.3
1.1
3.2
1.9
1.1
3.2
10
5.4 14.7
5.5
0.1
0.3
1.3
0.9
74 12.2 13.6
1
0.4
1.8
0.1
0.8
1.3
8.6 20.2
6.7
0.6
2.3 18.4
2.3 16.1
0.9
1.4
1.2
1.7
0.1
0.7
5.2 11.4
0.3
1
9.2
0.8
8.6 12.5
8.2
6
2.5
0.1
4.6
1.1
1.9
0.1
1.7
6.4 10.8
6.1
0.6
8
2.5
0.4
5.2
0.4
0.5
1.4 13.4
5.6
0.4
1.4
4.3
4.3
1.6
0.3
2.6
3.4
0.6
0.5
3.2 12.8
0.1
0.3
0.3
1
4.2
4.9
2.8
3.6 25.1 15.7 19.4
0.1 1.1
1.7
12.9
0.2
0.5
0.7
4 20.8
9.9
0.6
4.8
0.3
1.2 14.6
0.9
1.3
0.5
17.6
9.1
0.7
0.3 48.8
8.2
7.9
4
4.2
1.8
1.5
2
0.3
0.5
1.2
7
1.7
1.5
0.4
0.9
1.7 34.7 10.3 19.3
1.6
0.4
0
3.3 20.9
0.5
1.9
4.7
0.2
0.1
1.3
1.4
0.2
0.5
3.2
3.6 34.5
0.3
3.8
9.3
2.3
0.3
0.3
0.5
2.1
1.2
0.8
0.4
0.2
0.1
0.1
0
0.6
131
Table 10: continued
0.5
0
0.5
1
5
0.8
7.5
4.2
0.2
1.5
4.3
fall
summer
2011
spring
fall
summer
spring
fall
summer
spring
0.1
Welcome Island
2005
1999
fall
0.2
summer
0.3
spring
spring
2.3
fall
fall
0.1
Sturgeon Bay
2005
2011
summer
summer
0
1999
spring
1.5
2011
fall
0.2
spring
fall
summer
spring
Diatomeae cont.
Nitzschia sp.
Rhicosphenia abbreviata
Rhopalodia gibba
Stephanodiscus niagarae Ehrenberg
Stephanodiscus sp.
Stephanodiscus subtransylvanicus Gasse.
Surirella sp.
Synedra acus var. radians (Kütz.) Hustedt
Synedra nana Meister
Synedra sp.
Synedra ulna (Nitzsch) Ehrenberg
Synedra ulna v. danica
Tabellaria fenestrata (Lyngb.) Kütz.
Tabellaria flocculosa (Roth) Kütz.
Urosolenia eriensis Crawford & Mann
Urosolenia longiseta (Zach.) M. B. Edlund & Stoermer
Unknown Diatom
Cryptophyceae
Cryptomonas erosa Ehrenberg
Cryptomonas marssonii Skuja
Cryptomonas ovata Ehrenberg
Cryptomonas pusilla Bachmann
Cryptomonas reflexa Skuja
Cryptomonas rostratiformis Skuja
Cryptomonas sp.
Katablepharis ovalis Skuja
Rhodomonas lacustris Pascher & Ruttner
Rhodomonas lens Pascher & Ruttner
Rhodomonas minuta Skuja
Rhodomonas minuta var. nannoplanctica Skuja
Dinophyceae
Amphidinium sp.
Ceratium furcoides
Ceratium hirundenella
Glenodinium sp.
Gymnodinium helveticum Penard
Gymnodinium mirabile Penard
Gymnodinium sp.
Peridinium inconspicuum Lemmermann
Peridinium polonicum Woloszynska
Peridinium pusillum (Pénard) Lemmermann
Other
Aulomonas perdyi
Aulomonas sp.
Chlamydomonas granularis
Colorless flagellate
Gyromitus cordiformis Skuja
summer
Flatland Island
2005
1999
0.4
3.6
17
4.3
9.8
1.2
0.7
8.7
0.4
4
0.3
0
0.8
3.3
2.6
0.5
1.6
7.2
0.8
0.4
0.8
2.2
0.4 3.3
0.2
0.1
0.6
0.4
61.8 8.2 0.4 12.3 30.9 30.9
8.4
0.5
0.2 1.4
0.3
0.1
1.5 0.4
5.7
0.2
1.3 0.2
59.4 10.6
18.4 1.7
1.8 0.2 0.1
3.2 0.6
9.2 3.1 3.8
5.3
1.8 3.7
0.9
1.4
0.9 1.7
3.7
5.4 28.8
1.2 8.4
0.3 0.2
9.3 4.6
1.8
2.5 10.1 8.3 4.6 5.1 4.8 2.5
1.8 0.2
0.5 23.2
9.7
6.7 10.1
5.5 3.7
0.1
0.5
4.5
1.7
2.9 12.5
7.3
4.9 38.2
1.8
0.7
0.1
1.4
2.9
3.7
0.2
10.7
0.8
8.2
4 2.7 2.7 0.2 12.7 37.6
4.7
12.7
0.5 0.1 1.9
2.2
9.5
3.2
0.1 0.7 0.4
0.1
6.6
4.9 19.4
5.6
1.4
2.1
1.1
2.4
10.4
1.7
0.7
7.1
0.7
3.2
0.5
2.3
0.5 11.5
0.3 0.1
23.8
1.6
1.9
0.4
2.5
0.5
1.4
1.8
3.4
2.7
4
1.8
2.3 3.4 1.1 2.1 1.6
2 0.4
2.3
2.7
2.8 4.2
5
3.2
1.4
0.3
11.8
0.1
0.1
0.2
10.3
5.2
6
0.3
0.5
3.2 5.2
0.6
0.2
3.2
0.7
1.9
4.9
2.5
0.9
2.2
2.4
13.5
4.4 9.9
8.8
0.2 0.4 1.2
0.3
1.2 3.4 2.3 1.1 1.4 0.7
1.2
1.5 0.7
1.9
19
26.4
15.7
2.1 6.9 3.2
2.9
2.6
4.5
10.1
2
4.8
4.5
13
8.6
0.5
0.9
3.2
6.5
9.3
0.3
2.5
3.7
2.5
4.3 4.4 1.1 0.6
0.9
6.8
4.4
2.9
0.4
14.5
5.7
3.1
2.9
0.2
2.6
1.9
0.3
5.7
0.4
0.4
2.8
1.2
0.1 0.1
1.4
0.2
0.9
0.3
1.9
132
0.2
Table 11. Number of replicates, mean total zooplankton density (excluding copepod nauplii) and percent composition by density
(excluding nauplii) of all zooplankton taxa found seasonally (Sp=spring, Su=summer and F=fall) in Lake Superior. Copepod nauplii as
a percent of total density (nauplii included) are also shown. Data from: USGS (spring 1990 to 1992), OMNR (2005), OMOE Index
(1999 to 2011) and CSMI (2011). The dominant taxa are shown in bold. – indicates the taxon was not found. Stations within each
area are given in Tables 1-3.
% Composition by Density
Number of replicates
Apostle Islands
Su
F
Black Bay
Sp
Duluth Area
Sp
Su
5
2
7
Density (No.m-3) - w/o nauplii
5565
9447
4243
Total Cladocerans
29.4
26.5
4.8
-
9.9
0.0
1.4
10.4
0.2
4.6
2.9
-
1.4
24.8
0.2
0.1
-
3.5
0.9
0.1
0.1
0.1
0.0
0.0
-
15.0
17.4
81.9
1.4
13.5
17.4
53.2
28.7
72.3
56.1
7.5
0.1
17.1
4.8
0.7
5.2
5.7
31.1
2.8
9.5
1.4
0.2
18.2
3.5
20.4
13.3
11.4
Alona sp.
Bosmina longirostris
Bythotrephes longimanus
Chydorus sphaericus
Daphnia galeata mendotae
Daphnia pulex
Daphnia longiremis
Daphnia retrocurva
Daphnia sp.
Diaphanosoma birgeii
Eubosmina coregoni
Holopedium gibberum
Leptodora kindti
Polyphemus pediculus
Total Cyclopoids
Acanthocyclops vernalis
Diacyclops thomasi
Eucyclops agilis
Mesocyclops edax
Tropocyclops extensus
Cyclopoid copepodid
Total Calanoids
Epischura lacustris
Leptodiaptomus ashlandi
Leptodiaptomus minutus
Leptodiaptomus sicilis
Leptodiaptomus siciloides
Limnocalanus macrurus
Senecella calanoides
Skistodiaptomus oregonensis
Calanoid copepodid
Veligers
Copepod Nauplii (% of total)
2
F
Nipigon Bay
Sp
Su
F
Thunder Bay
Sp
Su
F
Coastal Superior
Sp
Su
F
Offshore
Su
F
13
5
5
48
7
3
8
7
1183 15992
3966
721
8543
3157
1359
2671
3
3
20
2
2
1596 10051
9661
2903
7685
6980
24.8
25.3
5.6
27.9
38.3
3.2
30.7
25.4
1.1
20.2
34.0
1.4
6.8
4.0
3.3
0.1
17.3
0.1
0.0
-
1.6
0.0
8.0
14.6
0.0
1.0
-
1.9
0.0
1.0
0.0
0.2
2.0
0.2
0.2
0.0
8.8
0.0
1.7
16.1
1.3
-
7.5
0.3
21.4
8.4
0.6
-
0.9
0.0
0.9
0.1
0.1
0.2
0.2
0.9
-
11.8
2.8
12.5
1.5
2.1
0.0
-
4.7
0.0
5.2
5.5
5.5
4.4
0.1
-
0.4
0.0
0.0
0.1
0.0
0.0
0.4
0.0
0.1
0.0
14.0
0.0
1.8
0.9
0.0
2.2
1.2
0.0
0.3
11.3
0.1
0.1
0.9
0.2
12.2
8.9
-
0.5
0.0
0.5
0.1
0.3
0.0
-
0.3
0.0
3.5
1.3
1.7
-
33.2
28.5
38.0
43.1
30.2
22.6
51.2
28.6
23.0
34.5
48.3
25.0
13.4
20.2
5.3
28.0
4.8
0.0
23.7
0.8
37.1
3.6
18.9
0.1
20.6
0.1
2.8
27.3
0.4
0.8
21.3
22.8
28.4
0.3
5.0
0.0
23.4
0.9
22.1
0.1
29.8
4.6
6.4
0.0
41.9
1.5
0.1
0.1
0.1
23.0
2.9
10.5
1.5
0.0
18.7
13.3
66.8
46.8
36.6
51.3
41.2
39.0
45.6
34.0
31.7
64.5
31.5
41.0
85.2
73.0
0.3
0.5
1.5
1.7
9.3
2.5
13.5
6.8
5.7
0.1
38.1
0.4
0.1
3.8
1.6
5.9
0.0
35.0
1.5
7.8
1.0
1.4
0.3
0.0
1.5
23.1
1.0
0.0
1.3
12.9
8.1
0.1
0.1
27.7
2.0
4.1
1.5
7.6
26.0
4.5
10.4
1.4
3.8
4.9
14.1
0.3
4.0
15.1
7.3
0.1
18.9
1.7
0.0
3.6
3.1
2.5
0.9
22.2
4.1
5.7
1.4
0.8
2.6
17.0
0.0
0.4
41.0
10.4
0.7
0.0
12.0
0.1
0.0
0.0
2.5
1.3
0.0
0.3
27.3
1.8
0.3
0.4
0.8
0.1
1.2
36.4
0.1
37.0
16.6
0.5
30.9
0.2
2.1
5.6
0.3
64.8
45.2
51.4
15.5
0.2
19.3
64.4
0.7
35.4
33.8
71.3
6.6
23.0
0.4
21.6
83.6
23.6
0.2
22.2
57.6
4.1
133
Table 12. Total number of taxa, mean zooplankton biomass (excluding copepod nauplii) and percent composition by biomass
(excluding nauplii) of all zooplankton taxa found seasonally (Sp=spring, Su=summer and F=fall) in Lake Superior. Copepod nauplii
as a percent of total biomass (nauplii included) are also shown. Data from: USGS (1990 to 1992), OMNR (2005), OMOE Index (1999
to 2011) and CSMI (2011). The dominant taxa are shown in bold. – indicates the taxon was not found. Mean weights of the taxa used
in these biomass calculations are also given.
% Composition by Biomass
mean Apostle Islands
wt (ug)
Su
F
Number of Taxa
Biomass (mg.m-3) w/o nauplii
Total Cladocerans
Alona sp.
Bosmina longirostris
Bythotrephes longimanus
Chydorus sphaericus
Daphnia galeata mendotae
Daphnia pulex
Daphnia longiremis
Daphnia retrocurva
Daphnia sp.
Diaphanosoma birgeii
Eubosmina coregoni
Holopedium gibberum
Leptodora kindti
Polyphemus pediculus
1.15
1.39
102.68
4.83
11.07
4.48
5.41
5.41
5.41
2.40
1.94
5.69
10.50
2.15
Total Cyclopoids
Acanthocyclops vernalis
Diacyclops thomasi
Eucyclops agilis
Mesocyclops edax
Tropocyclops extensus
Cyclopoid copepodid
4.55
3.56
1.43
6.99
0.93
1.11
Total Calanoids
Epischura lacustris
Leptodiaptomus ashlandi
Leptodiaptomus minutus
Leptodiaptomus sicilis
Leptodiaptomus siciloides
Limnocalanus macrurus
Senecella calanoides
Skistodiaptomus oregonensis
Calanoid copepodid
Veligers
Copepod Nauplii (% of total)
17.75
6.15
4.12
9.66
4.19
28.87
49.89
7.45
2.68
1.30
0.11
Black Bay
Sp
Duluth Area
Sp
Su
6
8.2
14
36.5
F
15
34.4
Nipigon Bay
Sp
Su
16.2
5.0
4.2
0.1
3.9
10.4
2.1
8.0
-
0.2
15.8
0.0
0.1
-
1.4
3.0
0.2
0.2
0.1
0.1
0.0
5.5
2.5
66.9
1.9
3.5
2.5
56.8
10.1
65.8
81.3
28.1
11.2
0.2
7.1
5.2
0.2
17.9
4.5
19.6
5.4
4.8
1.9
0.1
60.1
2.7
6.4
1.5
0.6
4.2
13.9
7.9
8.1
10.1
12.5
35.5
0.1
22.5
1.3
0.1
2.7
2.7
24.8
0.0
24.2
6.2
7.5
2.6
1.3
2.4
0.2
2.9
16.6
3.8
0.0
1.1
15.5
33.8
1.1
0.2
16.1
5.0
2.5
1.9
28.0
21.4
14.3
7.5
2.6
16.1
6.7
8.4
1.0
3.5
22.5
31.1
0.2
11.4
6.7
0.1
3.1
7.4
11.0
1.4
18.8
20.6
6.2
3.1
5.5
5.3
11.6
0.0
0.2
44.5
31.8
2.7
0.0
4.7
0.4
0.0
0.0
7.9
11.5
0.3
1.0
29.3
10.4
0.4
1.3
7.0
1.5
2.9
29.3
0.2
33.4
44.0
2.3
14.1
0.9
3.9
33.6
3.0
39.2
0.6
0.3
2.5
2.7
0.7
0.1
0.9
4.2
0.3
2.0
1.9
5.7
2.3
1.0
0.1
0.6
6.3
1.8
0.1
1.1
3.3
0.1
11.2 13.4 12.9
3.6
7.6
6.2
0.1
7.1
0.9
11.9
88.8 55.8 39.7
6.4 30.6 36.9
0.7
0.1
2.7
0.0
0.2
2.5
0.1
0.2
0.0
4.0
0.0
2.4
23.2
0.9
-
2.1
0.5
28.6
4.7
1.1
-
22.0 10.4
7.5
3.7
12.8
0.1
5.5
0.2
2.2
8.0
0.2
0.9
6.5
71.6 58.7 55.5
134
16
64.1
14
15.8
3.9 35.5 40.3
0.2
0.0
2.1
0.1
0.1
0.2
0.1
1.1
-
5.0
10.2
16.5
0.7
3.1
0.1
-
2.5
1.4
16.2
7.8
3.1
9.2
0.1
-
26.4 13.7
7.3
18.7
7.8
0.3
5.0
0.0
8.4
0.8
6.5
69.7 48.5 52.3
16
6.1
18
20.4
19
9.8
Offshore
Su
F
28.8
0.5
0.0
26.1
18.8
0.0
1.9
-
13
5.7
Coastal Superior
Sp
Su
F
12
15.2
1.2
7.7
0.0
21.6
0.2
0.1
-
12
26.0
F
10
69.2
-
12
28.4
Thunder Bay
Sp
Su
15
19.6
- 30.8 47.4
19
13.5
F
1.1 22.9 36.4
0.1
0.0
0.0
0.3
0.0
0.0
0.5
0.0
0.0
11
11.8
1.3 12.8
0.1
5.2
3.8
0.2
3.6
0.4
7.0
16.0
-
0.1
0.1
0.8
0.1
0.2
0.1
-
0.1
0.8
9.0
0.6
2.2
-
14.9 26.5 10.9
4.8
6.5
1.6
3.2
1.2
0.0
5.3
0.0
13.9
1.0
0.0
8.0
1.1
7.9
1.9
0.0
1.3
2.6
0.0
11
9.5
8.3
0.1
18.1
1.7
0.0
0.2
0.0
8.8
84.0 50.6 52.7
93.9 80.7
Figures
Figure 1: Map of the Thunder Bay area of Lake Superior showing stations sampled by various agencies between 1971 and 2014.
The approximate AOC boundary is indicated by the dashed line.
135
Figure 2: CSMI Lake Superior Study stations sampled by DFO, and embayments sampled seasonally in 2005 by OMNR.
136
a)
Cryptophycea
Diatomeae
Chrysophycea
Chlorophyta
Cyanophyta
300
b)
250
Dinophyceae
mg m -3
200
Cryptophyceae
Diatomeae
150
Chrysophyceae
100
Chlorophyta
Cyanophyta
50
0
June
Sep
Oct
3500
3000
mg m-3
2500
Dino
c)
Crypto
Diatom
Chryso
Chloro
Cyano
2000
1500
1000
500
0
May
August
Figure 3. Phytoplankton biomass (mg m-3) at offshore Thunder Bay station 139 during a) 1973
b) 1983 c) 2001.
137
800
a)
a)
1290
884
700
May
600
Sep
Nov/Dec
2000
300
700
600
b)
1734
Jun/Jul
Sep
500
400
300
200
100
1
2
3
12
15
17
22
25
31
43
50
51
52
62
69
70
84
89
92
100
102
115
127
133
139
149
157
165
169
180
189
196
203
207
218
220
221
0
Figure 4. Phytoplankton biomass (mg m-3) at all stations sampled during a) 1973, b) 1983 and c) 2001. Thunder Bay area stations
outlined.
138
221
196
169
157
139
127
115
100
80
68
59
51
0
45
0
31
500
12
100
5
9
12
17
28
31
43
50
62
69
72
80
86
89
95
105
106
121
127
139
144
164
169
178
183
192
194
196
203
205
212
214
220
221
1000
2
1500
200
800
May
August
2500
Oct
400
c)
c)
3000
Jul/Aug
500
mg m-3
3500
Jun
Jun
Sep
Nov/Dec
a)
3.0
12
3.5
3
mg C m-3 hr-1
mg C m-3 hr-1
2.5
Jul/Aug
Oct
2.0
1.5
1.0
1
2.5
169
144
139
127
95
89
80
72
69
62
43
28
17
0
12
0.0
b)
Oct
1.5
0.5
3
July/Aug
2
0.5
3.5
mg C m-3 hr-1
2.5
c)
2
23
31
43
51
68
80
100
113
127
139
164
169
177
196
201
221
3.5
May
August
2
1.5
1
0.5
2
12
31
42
43
51
59
68
76
80
95
100
115
127
139
157
169
196
221
0
Figure 5. Lake wide Primary Productivity (mg C m-3 hr-1) a) 1973 b) 2001 and c) 2011. Thunder Bay area stations outlined.
139
3500
Dino
Diatom
Chloro
3000
mg m -3
2500
Crypto
Chryso
Cyano
2000
1500
1000
500
0
1973
3.5
2001
1973
1983
2001
August
May
3
mg C m -3 hr -1
1983
2.5
2
1.5
1
0.5
0
100%
90%
% total productivity
80%
70%
60%
>20 um
50%
<20 um
40%
30%
20%
10%
0%
1973
2001
2011
1973
Summer
2011
Fall
Figure 6 Thunder Bay station 139 long term comparison of a) phytoplankton biomass (mg m-3) and
composition b) primary productivity (mg C m-3 hr-1) and c) proportion of productivity from large (>20
um) and small sized phytoplankton (<20 um).
140
450
400
Sturgeon Bay
400
350
300
300
mg m-3
350
250
250
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
2011
2005
2011
2005
2011
1999
0
2005
0
1999
50
2011
50
2005
100
1999
100
2011
150
2005
150
2011
200
200
1999
mg m-3
450
Welcome Island
100%
80%
60%
40%
20%
Spring
CYAN
CHRY
DIAT
CRYP
DINO
2011
1999 2011
Spring
Fall
Summer
CHLO
2005
1999
2011
2005
1999
2011
2005
1999
0%
Summer
Fall
CYAN Spring
CHLO
2005 2011
CHRY Summer
DIAT CRYP
2005 2011
DINO
Fall mixo
mixo
Figure 7. Phytoplankton biomass (mg m-3, top panels) and composition (lower panels) during the seasonal OMOE Index surveys in the Thunder
Bay area in 1999, 2005 and 2011. The Welcome Island station (284) is located in the outer AOC, and Flatland Island (283) is to the south of the
AOC. Sturgeon Bay (285), a coastal station to the east, was not sampled in 1999
141
60000
1971
Density (No.m-3)
50000
40000
30000
20000
10000
0
180
45
48
nauplii
Late
May
Biomass (mg.m-3)
160
50
45
48
50
Early July
calanoids
140
120
cyclopoids
100
cladocerans
80
60
40
20
0
45
48
50
45
Late May
48
50
Early July
Figure 8: Density and biomass of dominant zooplankton groups at stations in the Thunder Bay
area during the 1971 surveys by Watson and Carpenter. Station 48 indicated by the arrow is
located in the outer AOC.
142
Biomass (mg.m-3)
35
Biomass (mg.m-3)
June 1973
30
30
25
25
Cyclopoid
20
20
Cladocera
15
15
10
10
5
5
0
35
137
138
139
133
August 1973
140
142
0
35
30
30
25
25
20
20
15
15
10
10
5
5
0
35
Biomass (mg.m-3)
35
May 1973
calanoid
137
138
137
138
139
133
140
142
139
133
140
142
140
142
September 1973
0
137
138
139
133
October 1973
140
142
35
30
30
25
25
20
20
15
15
10
10
5
5
0
November 1973
0
137
138
139
133
140
142
137
Station
138
139
133
Station
Figure 9: Biomass of dominant zooplankton groups at stations in the Thunder Bay area during
the 1973 surveys by Watson and Carpenter. Station 139 indicated by the arrow is located in the
outer AOC. Copepod nauplii were not counted during this survey.
143
45
1990-1992
Biomass (mg.m-3)
40
Nauplii
35
Copepodites
30
Calanoid
Cyclopoid
25
Cladocerans
20
15
10
5
Thunder
Black
West Coastal
Nipigon
East Coastal
458
459
460
461
450
451
453
454
455
456
457
462
463
464
465
466
412
413
414
415
416
417
400
404
405
410
411
406
407
408
401
402
403
0
South Coastal
Station / Area
Figure 10: Mean biomass of dominant zooplankton groups found in June at nearshore USGS stations along the Canadian Lake
Superior coast, averaged over the 1990-1992 period.
144
7000
1200
Density (No.m-3)
1000
Cladocerans
6000
5000
800
4000
600
3000
400
2000
200
1000
0
0
401 402 403
Density (No.m-3)
Cyclopoids
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
406 407 408
401 402 403
410 400 404 405
406 407 408
410 400 404 405
1200
Nauplii
1000
Calanoids
800
600
400
200
0
401 402 403
Thunder Bay
406 407 408
Black Bay
410 400 404 405
Coastal
401 402 403
406 407 408
Thunder Bay
Black Bay
410 400 404 405
Coastal
Figure 11: Mean densities (±SE) of dominant zooplankton groups found in June at nearshore
USGS stations in the vicinity of Thunder Bay, averaged over the 1990-1992 period.
145
15000
Nauplii
copepodids
Calanoid
Cyclopoid
cladocerans
403 Pie Island
12000
9000
6000
3000
30
25
Biomass (mg.m-3)
Density (No.m-3)
18000
0
2001 2002 2003
401 Mackenzie
9000
6000
3000
3000
Density (No.m-3)
15000
1990 1991 1992
2001 2002 2003
400 Cloud Bay
6000
3000
N/A
0
2001 2002 2003
2013 2014
407 Black Bay
9000
6000
3000
0
N/A
1990 1991 1992
N/A
2001 2002 2003
402 Sawyer Bay
10
5
0
30
1990 1991 1992
2001 2002 2003
2013 2014
400 Cloud Bay
20
15
10
5
25
12000
2013 2014
15
0
30
Biomass (mg.m-3)
15000
1990 1991 1992
2001 2002 2003
20
25
9000
18000
0
30 1990 1991 1992
2013 2014
12000
401 Mackenzie
5
25
6000
2013 2014
10
402 Sawyer Bay
9000
2001 2002 2003
15
2013 2014
12000
0
18000
Density (No.m-3)
2001 2002 2003
1990 1991 1992
20
Biomass (mg.m-3)
Density (No.m-3)
15000
1990 1991 1992
5
25
12000
0
18000
10
0
30
2013 2014
Biomass (mg.m-3)
15000
1990 1991 1992
15
Biomass (mg.m-3)
Density (No.m-3)
18000
403 Pie Island
20
N/A
1990 1991 1992
2001 2002 2003
47
2013 2014
407 Black Bay
20
15
10
5
0
N/A
1990 1991 1992
2013 2014
N/A
2001 2002 2003
2013 2014
Figure 12: Mean densities and biomass of dominant zooplankton groups found in June at
nearshore USGS stations in the vicinity of Thunder Bay, from 1990-1992, 2001-2003 and 20132014. Years marked NA were not sampled. Biomass in 2003 at Black Bay was off the scale,
reaching 47 mg m-3.
146
40000
Zooplankton Biomass (mg.m-3)
Zooplankton Density (No.m -3)
45000
283 Flatland Is.
35000
30000
25000
20000
15000
10000
5000
1999
Oct
1999
May
2005
Aug
2005
Oct
2005
284 Welcome Is.
May
2011
Aug
2011
Oct
2011
30000
25000
20000
15000
10000
5000
Zooplankton Biomass (mg.m-3)
1999
Jul
35000
0
45000
Zooplankton Density (No.m -3)
May
40000
35000
30000
25000
Jul
May
Aug
Oct
May
Aug
Oct
2011
2011
2011
calan
cyclo
other
15000
daphnia
5000
Oct
285 2005
Sturgeon
1999nauplii
1999 1999
2005 Bay
2005
20000
10000
50
40
30
20
10
70
60
May
Jul
Oct
May
Aug
Oct
May
Aug
Oct
1999
1999
1999
2005
2005
2005
2011
2011
2011
May
Jul
Oct
May
Aug
Oct
May
Aug
Oct
1999
1999
1999
2005
2005
2005
2011
2011
2011
284 Welcome Is.
50
40
30
20
10
0
May
bos not sampled
0
Zooplankton Biomass (mg.m-3)
Zooplankton Density (No.m-3)
40000
283 Flatland Is.
60
0
0
45000
70
70
60
285 Sturgeon Bay
50
40
30
20
10
0
May
Jul
Oct May Aug
Oct May Aug
Oct
1999 1999 1999 2005 2005 2005 2011 2011 2011
May
Jul
Oct
May Aug
Oct
May Aug
Oct
1999 1999 1999 2005 2005 2005 2011 2011 2011
Figure 13: Density and biomass of dominant zooplankton groups during the seasonal OMOE
Index surveys in the Thunder Bay area in 1999, 2005 and 2011. The Welcome Island station is
located in the outer AOC, and Flatland Island is to the south of the AOC. Sturgeon Bay, a
coastal station to the east, was not sampled in 1999.
147
16000
120
Apostle Islands
2005
100
Biomass (mg.m-3)
Density (No.m-3)
20000
12000
8000
4000
80
60
40
20
0
0
AI50
20000
June
16000
Duluth
2005
AI50 AI100
September
Month/ Station
AI10 AI100
October
AI10
12000
8000
4000
June
100
Duluth
2005
60
40
20
DS10 DS50
late Sep.
Nipigon Bay
2005
120
100
Biomass (mg.m-3)
Density (No.m-3)
DS10 DS100
early Sep.
8000
4000
0
20000
June
16000
Thunder Bay
2005
NB10 NB100
August
Month/ Station
80
4000
DS10 DS100
early Sep.
DS10 DS50
late Sep.
NB10 NB100
August
NB10 NB50
October
Nipigon Bay
2005
60
40
20
NB10 NB50
120
100
8000
DS10 DS50
June
0
NB10 NB50
October
Biomass (mg.m-3)
NB10 NB50
Density (No.m-3)
Month/ Station
AI10 AI100
October
0
DS10 DS50
June
12000
12000
AI50 AI100
September
80
0
16000
AI50
120
Biomass (mg.m-3)
Density (No.m-3)
AI10
20000
Apostle Islands
2005
0
80
June
Month/ Station
calanoids
cyclopoids
Thunder Bay
2005
Holopedium
60
Daphnia
40
bosminids
20
0
TB10 TB50 TB100
Spring
TB10 TB50
Summer
Month/ Station
TB10 TB50 TB100
Fall
TB10 TB50 TB100
Spring
TB10 TB50
Summer
Month/ Station
TB10 TB50 TB100
Fall
Figure 14: Density and biomass of dominant zooplankton groups during the seasonal OMNR
surveys in Lake Superior embayments in 2005. Nauplii were abundant but not included as they
were not consistently sampled due to differences in net mesh size.
148
Figure 15: Total water column biomass of dominant zooplankton groups during the summer
2011 and fall 2011 CSMI surveys completed by DFO. Samples were collected using a 153 µm
net, so nauplii and veligers were not sampled effectively.
149
403
403
284
284
403
403
403
284
403
403
403
139
139
48
Spring
284
139
284
284
71 72 73 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 11 12 13 14
403
403
284
139
284
403
403
403
284
403
403
403
139
139
Fall
48
10000
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
139
139
Summer
48
Zooplankton Density (No.m-3) Zooplankton Density (No.m-3)
Zooplankton Density (No.m-3)
10000
copepodid
9000
calanoid
8000
7000
cyclopoid
6000
cladocerans
5000
4000
3000
2000
1000
0
45000
40000 71 72 73 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 11 12 13 14
35000
30000
25000
20000
15000
10000
5000
0
71 72 73 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 11 12 13 14
Station / Year
Figure 16: Densities of zooplankton groups at stations within the outer Thunder Bay AOC
between 1971 and 2014. Note that the scale for the summer densities is different. Station 403
was only sampled in June. Copepod nauplii, though numerically dominant, are not included as
they were not counted consistently.
150
PHYTOPLANKTON AND ZOOPLANKTON POPULATIONS: CONCLUSIONS
While information on plankton populations is scarce for both Toronto Region AOC and Thunder
Bay AOC, all available historical information including results from the DFO’s 2010 Ecosystem
Research Initiative (ERI), OMOECC Index sampling, and the 2013 GLLFAS survey of Toronto is
documented in this report.
Section 1:
The Toronto Region planktonic ecosystem study was a lone survey during the week of Sept 913, 2013 from Etobicoke to Pickering, the boundaries of the AOC. The purpose was to
determine the distribution of zooplankton, chlorophyll and physical water characteristics using
DFO’s towed SHRIMP sensor array, but to enhance this spatial survey (for the 2013 CSMI),
station sampling was included for physical characteristics, water chemistry, and collection of
phytoplankton, microbial loop and zooplankton for taxonomy, which are made available.
During the survey, the entire Toronto coastline experienced a strong, widespread upwelling
which greatly affected the distribution of physical characteristics, chlorophyll, and zooplankton
densities. In particular, the area near Ashbridges Bay along the scarp was highly affected by the
upwelling making any determination of impact by factors such as the sewage treatment outfall
difficult for this survey. Though much reduced in intensity, Humber Bay, the source water for
Toronto Harbour, was also influenced by the upwelling. Humber Bay also showed weak
stratification for all of 2013, likely due to its orientation to the northwest, the dominant prevailing
wind direction. Frequent upwelling forces combined with the internal seiche of the lake is likely
to create very specific physical mixing conditions in Humber Bay unique to Lake Ontario, so
comparisons to other embayments will be difficult.
Toronto Inner Harbour was very different from surrounding habitat in physical water
characteristics with elevated values for temperature, turbidity and chlorophyll but much reduced
primary production, densities of zooplankton and phytoplankton and differing composition.
Phytoplankton composition was highly variable between stations although there was a
preponderance of flagellated forms capable of self-directed movement. Primary production was
depressed in the Harbour except at the Don River mouth, which also had higher chlorophyll-a,
turbidity and total phosphorus. Driven in part by river discharges, bacterial production was
elevated within the Harbour and in Humber Bay. Zooplankton particle densities were highly
reduced in the Harbour compared to other coastal and other embayment habitats, especially for
the eastern portion of the AOC which had much higher densities. This was unexpected since
zooplankton should be able to retain themselves in the Harbour, even during an upwelling
event. This, added to low counts found during other past surveys, and the lack of change in
rotifer densities, suggests the possibility that Toronto Harbour may not be a suitable habitat for
plankton populations. A single snapshot spatial survey is however not adequate to properly
assess the zooplankton and phytoplankton BUI of the Toronto AOC. Further sampling should
involve at least monthly sampling of zooplankton and phytoplankton from May-Oct to determine
population structure over the spring-fall period and possibly population growth studies using
incubations, in addition to tracking the effect of planktivory from fishes.
Section 2:
The use of the Ontario Ministry of the Environment (and Climate Change) Nearshore Index
archived plankton samples, in of themselves, were found to be insufficient to determine the
status of BUI 13 with regards to densities or composition of zooplankton or phytoplankton. The
sampling program of three times per year, every three years for Toronto Harbour is too sparse
to account for the underlying variability within plankton populations and determine differences
151
between sites. A power analysis indicated that at least 50-60 samples would be needed from
each site to resolve differences between 2 locations (within AOC to a reference site), and the
years of sampling has not been the same for each Index site, so pairing sites is additionally
difficult. An additional difficulty is in the timing of the early sample in April, which was chosen to
target the freshet runoff and resulting increased chloride inputs. Zooplankton composition is
generally limited to overwintering juvenile copepod stages at this time of the year so is not
comparable to any other studies. The “fall” sample in November is also very late in the year,
leaving only a single sample in August per year for comparison to other sampling programs.
Lastly, the taxonomist notes that that the other nearby coastal Index sites have different
planktonic species compositions than Toronto making them unsuitable reference conditions.
A comparison of DFO to MOECC sampling frequency in Hamilton Harbour for two sampling
years indicated that the three samples taken per year by MOECC is insufficient to account for
changes in species composition and density over the sampling season. In particular, the
dominant genus Bosmina, is almost completely absent from the Index sampling due to lack of
sampling during June and July. Furthermore, estimated zooplankton densities were only half of
that found by DFO biweekly sampling. It is recommended that a minimum of monthly sampling
is necessary for zooplankton resulting in at least 6 samples per sampling year. Phytoplankton
populations have higher variability so are likely to require even more frequent samples to
accurately sample species composition.
Section 3:
All available plankton and coinciding physical-chemical data from the Thunder Bay area is
documented from DFO, MOECC Index, MNRF and USGS programs, along with other
embayment, coastal and offshore areas in Lake Superior. Data contained in this report could be
used as a baseline for lake-wide changes over time or reference for any new studies.
Some governmental program sampling takes place during less ideal periods early in the year,
since they are not targeting plankton (e.g. USGS since 1990 in June and MOECC in May),
when zooplankton consists of only copepods and their nauplii stages, which are undersampled
by the use of large-mesh nets. Most differences among areas develop through the summer as
cladocerans and other taxa preferring warmer temperatures appear, which occurs earlier in
protected embayments. However, most previously sampled Thunder Bay area stations are
either located outside of the AOC boundaries or are at the southern, lake-mixed, coastally
influenced portion of the AOC. In order to properly assess whether phytoplankton and
zooplankton populations within the Thunder Bay AOC are impacted, it is necessary to sample
the areas where impacts are most likely to occur (e.g. turbidity, contaminated sediment). The
Thunder Bay RAP identified the Kaministiquia River, the inner Thunder Bay Harbour and
Chippewa Beach as the areas of highest degradation, with impacts radiating out from the river’s
delta. Sampling should be carried out at several stations along a gradient away from the most
impacted areas. Sampling would ideally be done six times per year with emphasis on the July to
September period when the zooplankton community is most developed. This would provide data
on spatial variability within Thunder Bay harbour, and determine if a trophic gradient exists.
152
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising