Prepared By:
United States Environmental Protection Agency
Great Lakes National Program Office
United States
Environmental Protection
Agency
Great Lakes
RESTORATION!
Status and Trends through 2014 for Chlorophyll, Phytoplankton,
Zooplankton and Benthos; and through 2016 for Mysis
GREAT LAKES BIOLOGY
MONITORING PROGRAM
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
ACKNOWLEDGMENTS
This work was supported by the U.S. Environmental Protection Agency (USEPA) Great Lakes National
Program Office (GLNPO) as part of EPA Contract No. EP-C-15-012, Technical, Analytical, and
Regulatory Mission Support for the Water Security Division, with CSRA, LLC, a General Dynamics
Information Technology (GDIT) company, under the direction of Louis Blume, Project Manager as well
as by agreements with Cornell University (Department of Natural Resources) under award agreement GL-
00E01184 from the USEPA "Great Lakes Long Term Biological Monitoring of Zooplankton, Benthos,
and Chlorophyll-a" and with Regents of the University of Minnesota from the USEPA under award
agreements GL-00E23101-2 and GL-00E01980 "Great Lakes Biological Monitoring: Phytoplankton."
We gratefully acknowledge the support of the following team members in the preparation of this
Technical Report:
Affiliation
Team Member(s)
USEPA GLNPO
Elizabeth Hinchey, Todd Nettesheim, Marc Tuchman, Louis Blume
Cornell University
Jim Watkins, Lars Rudstam,
Buffalo State College
Lyubov Burlakova, Alexander Karatayev
University of Minnesota
Euan Reavie
Duluth
Oak Ridge Institute for
Katelyn Bockwoldt
Science and Education
GDIT
Richard Barbiero, Barry Lesht, Julie Lietz, Molly Middlebrook Amos
Cover Photo Credit: Conrad DeBarros
Citation: U.S. EPA 2019. Great Lakes Biology Monitoring Program Technical Report: Status and Trends
through 2014 for Chlorophyll, Phytoplankton, Zooplankton and Benthos; and through 2016 for Mysis.
(EPA 95 0-R-19-001)
JULY 2019
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
TABLE OF CONTENTS
Acknowledgments i
List of Figures iii
1 Executive Summary 1
2 Introduction 3
3 Historical Sampling Context 4
4 Description of Sampling Methods 4
4.1 Phytoplankton 5
4.2 Zooplankton and Mysids 5
4.3 Benthos 6
5 Laboratory Methods 6
5.1 Phytoplankton 6
5.2 Zooplankton and Mysids 6
5.3 Benthos 6
6 Remote Sensing of Surface Chlorophyll 7
6.1 Description of Analysis 7
6.2 2014 Surface Chlorophyll 7
6.3 Surface Chlorophyll Trends from 1998 to 2014 8
7 Phytoplankton 12
7.1 Community Composition in 2014 12
7.2 Community Composition from 2001 to 2014 12
7.3 Community Trends from 2001 to 2014 13
8 Zooplankton 19
8.1 Community Composition in 2014 19
8.2 Community Composition Trends from 1997 to 2014 20
9 Mysis 24
9.1 Abundance in 2014 24
9.2 Population Trends from 2006 to 2016 24
10 Benthos 27
10.1 Community Composition in 2014 27
10.2 Community Composition Trends from 1997 to 2014 29
References 32
Appendix A - List of the Sampling and Analytical Standard Operating Procedures Supporting the
GLBMP Components A-l
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Figure 1. Map of GLNPO long-term monitoring stations for annual spring and summer nutrients and
plankton sampling (includes phytoplankton, zooplankton. Mysis) and summer benthos sampling 5
Figure 2. Monthly average surface chlorophyll-a concentrations estimated from satellite
observations 8
Figure 3. Monthly averaged (March-October) surface chlorophyll-a concentrations at station
locations in Lake Erie for the period 1998-2014 9
Figure 4. Monthly averaged (March-October) surface chlorophyll-a concentrations at station
locations in Lake Ontario for the period 1998-2014 10
Figure 5. Monthly averaged (March-October) surface chlorophyll-a concentrations at station
locations in Lake Michigan for the period 1998-2014 10
Figure 6. Monthly averaged (March-October) surface chlorophyll-a concentrations at station
locations in Lake Huron for the period 1998-2014 11
Figure 7. Monthly averaged (March-October) surface chlorophyll-a concentrations at station
locations in Lake Superior for the period 1998-2014 11
Figure 8. Phytoplankton biovolume and percent biovolume, by major taxonomic group, for spring and
summer, 2014 14
Figure 9. Phytoplankton biovolume and percent biovolume, by major taxonomic group, in Lake Erie
for spring 2001-2014 15
Figure 10. Phytoplankton biovolume and percent biovolume, by major taxonomic group, in lakes
Ontario, Huron, Michigan and Superior for spring 2001-2014 16
Figure 11. Phytoplankton biovolume and percent biovolume, by major taxonomic group, in Lake Erie
for summer 2001-2014 17
Figure 12. Phytoplankton biovolume and percent biovolume, by major taxonomic group, in lakes
Ontario, Huron, Michigan and Superior for summer 2001-2014 18
Figure 13. Crustacean volumetric biomass and percent volumetric biomass, by major taxonomic
group, for spring and summer, 2014 19
Figure 14. Crustacean volumetric biomass and percent volumetric biomass, by major taxonomic
group, for spring 1998-2014 21
Figure 15. Crustacean volumetric biomass and percent volumetric biomass, by major taxonomic
group, for summer 1997-2014 23
Figure 16. Mysis diluviana areal density (mg DW/m2) trends from 2006-2016 25
Figure 17 .Mysis diluviana areal biomass (mg DW/m2) for stations deeper than 30 meters, averaged
across years for the spring and summer surveys (2006/7-2016) 26
Figure 18. Absolute and percent areal biomass of benthos by major taxonomic group excluding
Dreissena spp. and areal biomass of Dreissena spp. at shallow and deep stations in 2014 28
Figure 19. Trends in benthos areal density and percent areal density of major taxonomic groups in
Great Lakes (1997-2014) < 70 meters depth 29
Figure 20. Trends in benthos areal density and percent areal density of major taxonomic groups in
Great Lakes (1997-2014) > 70 meters depth 30
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
1 EXECUTIVE SUMMARY
The United States Environmental Protection
Agency (USEPA) Great Lakes National Program
Office (GLNPO) Great Lakes Biology Monitoring
Program (GLBMP) annually adds observations to
the most comprehensive collection of consistent
data describing the lower food web of the Great
Lakes. The data generated by the GLBMP are
essential for understanding the current status and
recent trends of critical lower food web
components of the Great Lakes" ecosystem. This
report summarizes the GLBMP historical record of
phytoplankton (2001-2014), zooplankton (1997-
2014), Mvsis (2006/2007-2016), and benthic
(1997-2014) communities and estimates of
remotely sensed chlorophyll (1998-2014) in all
five Great Lakes.
LOWER FOOD WEB STATUS (2014)
• Chlorophyll-a concentrations in the surface
waters estimated from satellite observations
continue to be low overall compared to
historical levels. Although highly variable in
the western and central basins of Lake Erie
and Lake Ontario, annual average
concentrations in lakes Michigan and Huron
are at or near the lowest values observed by
satellite (1998-2014) and have remained
relatively stable in Lake Superior. This
suggests an overall decline in primary
production in the upper water column in some
lakes, though compensating production may
be occurring at depths below that sampled by
the satellite sensors.
• Phytoplankton biovolumes are higher in the
summer than in the spring in all lakes. Spring
communities are dominated by diatoms, along
with cryptophytes and dinoflagellates.
Summer communities in the western and
central basins of Lake Erie are dominated by
cyanophytes, with diatoms continuing to
dominate elsewhere. Low phytoplankton
biovolumes relative to previous years in lakes
Huron and Michigan are consistent with lower
levels of primary production implied by the
low chlorophyll-a concentrations.
• Zooplankton biomass is also higher in the
summer than in the spring. In the summer,
the zooplankton volumetric biomass follows
the lakes" trophic gradient with highest
values in western Lake Erie and lowest
values in Lake Superior. Community
composition also follows a trophic gradient
with a reduction in cladoceran and cyclopoid
biomass and an increase in calanoid biomass
associated with decreasing productivity.
Biomass and community composition are
very similar in lakes Huron, Michigan, and
Superior. A new (to the Great Lakes)
zooplankter (Thermocyclops crassns, a small
Eurasian cyclopoid copepod) was found in
western Lake Erie in the 2014 sampling.
• Mysid shrimps are relatively large crustacean
zooplankton, an important link between
benthic and pelagic components of the food
web, and an especially lipid-rich food source
for fish. Mysids are found in all five lakes,
though their abundance differs substantially
among the lakes. In 2014, Mysis was most
abundant in Lake Ontario and very rare in
Lake Erie. Populations in Lake Huron were
about 10% of those in lakes Michigan and
Superior.
• The benthic communities in all lakes except
Superior are dominated by the invasive
quagga mussels. After mussels, oligochaetes
are the second most abundant benthic
organism in the shallower (<70 meters)
regions of all lakes except Superior. The
previously abundant burrowing amphipod
(Diporeici) has essentially disappeared from
the shallow areas of all the lakes except Lake
Superior, where they remain dominant.
Diporeici are still present in the deeper areas of
lakes Huron and Michigan, but they are
virtually absent from the deeper areas of Lake
Ontario.
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
LOWER FOOD WEB TRENDS
The structure of the lower food web in the Great
Lakes has undergone dramatic changes since the
GLBMP began consistent multi-trophic level
monitoring in 1997. Because the several
components of the lower food web are
interconnected, analysis of each component is
essential for developing an understanding of the
different factors that may be responsible for the
changes observed from 1997-2014/2016.
• Analysis of satellite-derived estimates show a
general increase in late summer chlorophyll-a
concentrations in western Lake Erie.
Concentrations in the central basin of Lake
Erie also tended to increase over the years
primarily due to a reduction in the duration of
the period of post-spring bloom minima.
Although much lower than in the west and
central basins of Erie, average concentrations
in the eastern basin of Lake Erie and in Lake
Ontario have been increasing as well. In
contrast, the spring bloom in lakes Huron and
Michigan have disappeared, being last clearly
discernable in Huron in 2004 and Michigan in
2005. These rapid declines may be due to
nutrient sequestration and direct consumption
of phytoplankton by Dreissena mussels
(hereafter Dreissena) as well as other potential
causes. Spring chlorophyll concentrations in
Lake Superior also appeared to decline after
2004, though this decline is relatively small
and, in the absence of Dreissena in that lake,
the mechanism for the decline is unclear. In
recent years, highest chlorophyll
concentrations appear to occur in the autumn
in all lakes except Erie.
• In accordance with the chlorophyll-a
estimates, summer phytoplankton biovolume
measurements are variable in both lakes Erie
and Ontario. The abundance of cyanophytes
has increased during the summer in these
lakes, while spring diatom abundances are
dominated by centric diatoms. Spring diatom
abundances have dropped significantly in
lakes Michigan and Huron in fairly close
correspondence with the declines in
chlorophyll-a. In contrast to the other lakes,
phytoplankton biovolume estimates for Lake
Superior suggest an increase in spring and
decrease in summer.
• Summer crustacean communities in Lake Erie
are variable with no overall trend. In Lake
Ontario, however, the community began a
clear shift from cyclopoid dominance to
calanoid dominance around 2004. A further
shift was noted from 2008-2011 marked by
increased biomass of Leptodiaptomns sicilis,
Bvthotrephes longimanus, and Daphnia
mendotae. Both lakes Michigan and Huron
showed substantial losses of crustacean
biomass again occurring at approximately the
same time as the reductions in chlorophyll-a
and phytoplankton. These reductions were
primarily due to declines in cladoceran
biomass. Zooplankton populations in Lake
Superior have been relatively stable and
dominated by calanoid copepods.
• Mysis biomass remains low in Lake Erie, where
they are only found in the deeper portions of
the eastern basin, and remains high in lakes
Ontario (where the populations do vary
annually but without clear pattern), Michigan
and Huron. Mysis abundance in Lake Superior,
however, has increased since 2007. Populations
in Lake Huron are about 10% of those in lakes
Michigan and Superior.
• Dreissena, in particular quagga mussels, now
dominate the benthic communities in all lakes
except Superior. The increase in Dreissena has
been accompanied by the disappearance of
Diporeia while oligochaete abundances have
remained stable. Because of the decline in
Diporeia, Dreissena, and oligochaete s now
dominate the benthic community in lakes Erie,
Ontario, Michigan, and Huron.
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
2 INTRODUCTION
In this report we present the biological data
collected as part of the United States
Environmental Protection Agency (USEPA) Great
Lakes National Program Office (GLNPO) Great
Lakes Biology Monitoring Program (GLBMP).
Data from 2014 are presented in the context of
historical data from consistent time series for
phytoplankton (2001-2014), zooplankton (1997-
2014), mysids (2006/7-2016) and benthos
(1997/1998-2014). In addition, chlorophyll-a
concentrations estimated from remote sensing
data, validated with extracted chlorophyll
generated from the GLNPO monitoring program
(Lesht et al. 2013). are presented from 1998 to
2014. Our goal is to provide a brief general
description of the status of the lower food web of
all five Great Lakes in 2014, and to highlight the
most important trends in chlorophyll-a,
phytoplankton, zooplankton and benthos.
Community trend results are generally presented
in the order to span the trophic gradient: Erie,
Ontario, Michigan, Huron, and Superior.
USEPA GLNPO has conducted regular monitoring
of the Great Lakes since 1983. This GLBMP helps
EPA to satisfy our statutory requirements under
section 118 of the Clean Water Act to establish a
Great Lakes system-wide surveillance network to
monitor the water quality of the Great Lakes. It also
helps satisfy our obligations under the Great Lakes
Water Quality Agreement to "monitor
environmental conditions so that the Parties may
determine the extent to which General Objectives,
Lake Ecosystem Objectives and Substance
Objective are being achieved," and "undertake
monitoring and surveillance to anticipate the need
for further science activities and to address
emerging environmental concerns." Further, this
program allows EPA to meet commitments in the
GLRI Action Plan II to "assess the overall health of
the Great Lakes." The monitoring effort is designed
to track whole-lake responses to changes in
environmental stressors, so sampling is largely
restricted to the relatively homogeneous offshore
waters of each lake. As the initial focus of the
surveys was on chemical eutrophication and the
response of the lakes to changes in phosphorus
loading, spring surveys were originally initiated to
provide data to establish whole-lake nutrient
concentrations, while summer surveys were aimed
at determining epilimnetic depletion and
hypolimnetic enrichment of nutrients. GLNPO also
uses the spring and summer surveys to collect lower
food web data that are important for fisheries
management and non-native species detection.
Because of the logistical challenges of sampling a
waterbody as large as the Great Lakes, temporal
resolution is currently limited to two well-defined
periods during the year: the spring isothermal
period (March/April/May depending on ice cover),
and the stable, stratified summer period (August).
More context on the development of the GLNPO
surveys is provided in Barbiero et al. (2018a) and
Burlakova et al. (2018b).
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
3 HISTORICAL SAMPLING
CONTEXT
GLNPO's monitoring of the Great Lakes began in
1983 in lakes Michigan, Huron and Erie. Sampling
was extended to include Lake Ontario in 1986 and
Lake Superior in 1992. In addition to a wide range
of physical and chemical parameters, the lakes
have been sampled for phytoplankton and
zooplankton since the inception of the program.
However, inconsistent data collection over the
years has resulted in truncated time series for these
two variables. Inconsistencies in phytoplankton
taxonomic identification have led to a break in
comparability between older and more recent data;
thus, in this report we present phytoplankton data
from only 2001-2014, which represents years for
which a consistent time series exists. From 1983—
1996, zooplankton tows were collected primarily
from a depth of 20 meters. Such samples do not
cover all depths inhabited by zooplankton, and
show large differences between samples collected
day and night; therefore, they represent an
incomplete picture of the zooplankton community.
Tows to a depth of 100 meters were added to the
monitoring program in 1997. Data from these
deeper tows are reported here, as they are more
representative of the total zooplankton community.
Sampling for My sis diluvictnct, a key zooplankton
species in the offshore food web, was initiated in
2006 in lakes Michigan and Huron and in 2007 in
the other three lakes. While historically
enumerated in GLBMP zooplankton samples, this
crustacean species is not effectively sampled with
the standard 100-meter zooplankton tows. A
benthic invertebrate biomonitoring program was
initiated in summer of 1997. Dreissena spp. (the
zebra mussel D. polymorphct, and the quagga
mussel D. rostriformis bugensis) were first
enumerated in 2003. A remote sensing component
was added to the program in 2010 making it
possible to fill the temporal and spatial gaps for
chlorophyll-a in the field survey data and assess
spatial variability on kilometer scales back to
1998.
4 DESCRIPTION OF
SAMPLING METHODS
During the annual surveys, samples for nutrients,
phytoplankton, and zooplankton are collected from
72 regular open water stations (Appendix A
provides a complete list of standard operating
procedures). Mysid samples are taken when a
station is visited at night. Benthos samples are
taken from 33 of these "plankton" stations, as well
as from an additional 25 exclusively benthos
stations (Figure 1) during the August survey. In
2014, spring sampling was undertaken on lakes
Michigan, Huron, Erie and Ontario between April
17 and April 26, and on Lake Superior between
May 15 and May 18. Extensive ice cover in the
winter of 2013-14 delayed spring sampling in all
lakes, which usually commences the last week of
March or the first week of April. Summer
sampling occurred between August 6 and August
28.
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
42° N
Figure 1. Map of GLNPG long-term monitoring stations for annual spring and summer nutrients and
plankton sampling (includes phytoplankton, zooplankton, My sis) and summer benthos sampling.
4.1 PHYTOPLANKTON
At each station, integrated samples for
phytoplankton enumeration were created from a
composite of water samples taken at discrete
depths (spring integrated sample: surface, 5
meters, 10 meters, and 20 meters; summer
integrated sample: 2 to 4 depths in the epilimnion;
summer deep chlorophyll layer also sampled when
present) with Niskin bottles mounted on a SeaBird
Carousel Water Sampler. Samples were preserved
in the field with Lugo I s solution, and with
formalin upon return to the laboratory. From
2001-2006, phytoplankton were analyzed from a
limited number of stations.
4.2 ZOOPLANKTON AND MYSIDS
Two vertical net tows (one 20-meter depth tow
and one 100-meter tow) were performed at each
site for zooplankton sample collection, except in
Lake Superior where duplicate net tows are
collected, using a 0.5-meter diameter conical net
equipped with a TSK (Tsurumi Seiki Co., Ltd.)
flowmeter. Hie first tow was taken from 20 meters
below the water surface or 2 meters above the
bottom, whichever was less, using a 64-p.m mesh
net, and the second tow was taken from 100
meters below the water surface or from 2 meters
above the bottom, whichever was less, using a
153-^m mesh net. Only data from 153-f.im mesh
net tows are reported here.
A larger 1-meter diameter net towed vertically
from 2 to 5 meters from the bottom to the surface
at night was used to measure mysid abundance.
Replicate tows were performed at stations visited
at night from 1 hour after sunset to one hour
before sunrise with all lights except navigation
lights on the research vessel turned off. Only red
light that is not visible to mysids (Gal et al. 1999)
was used during these tows. Stations shallower
than 30 meters are typically not sampled for
mysids. Mysids avoid even very low light levels
(Gal et al. 1999: Boscarino et al. 2010) and can
avoid smaller-sized nets.
90° W 87° W 84° W 81° W 78* W 75° W
48° N
45° N
Station
O Plankton
• Benthos
3 Plankton/Benthos
125 250 Km
l l I I
Projection: Albers Equal Area
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
4.3 BENTHOS
During the summer survey, quantitative samples
for benthic invertebrate analysis were collected
from selected stations using a Ponar grab sampler
(surface area 0.0523 m2). Samples were taken in
triplicate, and material sieved through a 500-(.un
mesh net. Samples were preserved with buffered
formaldehyde with Rose Bengal to a final
concentration of 5-10% formaldehyde.
5 LABORATORY METHODS
5.1 PHYTOPLANKTON
Phytoplankton were identified and abundances
were estimated using the Utermohl technique
(Lundetal. 1958) at a magnification of 500x, with
diatoms other than Rhizosolenia identified as
either centrics or pennates. Diatoms were
identified, and relative abundances determined,
from permanent slide mounts at 125 Ox. Relative
proportions of each taxon of centrics and pennates
were then multiplied by the appropriate Utermohl
quantitative counts. At least 10 individuals of each
taxon were measured per sample, and cell volumes
computed using appropriate geometrical formulae
listed in EPA SOP LG401 (rev 5, 2010). Primary
taxonomic keys used were Prescott (1962),
Krammer and Lange-Bertalot (1986, 1991, 1997),
Patrick and Reimer (1966, 1975) and Germain
(1981).
5.2 ZOOPLANKTON AND MYSIDS
Samples for zooplankton analysis were split in the
lab using a Folsom plankton splitter, and four
stratified aliquots examined per sample using a
stereoscopic (crustaceans) or compound (rotifers)
microscope. Two subsamples of 200-300
crustaceans were identified to the lowest practical
taxonomic group (mostly species). Rarer species
were enumerated in additional subsamples. Mysis.
Cercopctgis and Bvthotrephes were identified in
the whole sample. Copepods were identified as
immature, mature males or mature females.
Nauplii, veligers and rotifers were not counted in
the 100-m tows and therefore not reported here.
Primary taxonomic keys used were Balcer et al.
(1984). Hudson et al. (1998). Brooks (1957).
Evans (1985). Edmondson (1959) and Rivier
(1998). Length measurements were made on the
first twenty individuals of each species
encountered per sample and dry mass calculated
from length-weight regressions (listed in EPA
SOP LG403, rev 8, 2017). Because constants for
length-weight regressions were updated in 2017,
the data presented here deviate somewhat from
earlier publications. All data since the initiation of
the 100-meter deep tows in summer 1997 are
presented except for spring 2000, which has not
yet been analyzed. Data are presented as
volumetric biomass (mg DW/m3). Comparisons of
volumetric density in the water column across
lakes with different maximum depths is
problematic because individuals are not evenly
distributed throughout the water column. As a
result, low zooplankton densities in deep water
will dilute average water column biomass
estimates in deep lakes. However, comparisons
among the deeper lakes is appropriate because the
depths sampled are similar. Comparisons across
time are the same regardless of whether whole
water column summed values (areal) or average
values per m3 are used since the same stations are
visited each year.
Mysids were counted from the mysid net sample
and the first 100 individuals were photographed
and measured (tip of rostrum to end of abdomen)
following EPA SOP LG408 (rev 2, 2017). Lengths
were converted to dry biomass using Johannsson
(1995) length-weight regression as modified by
Rudstam et al. (2008).
5.3 BENTHOS
Benthic organisms were picked out of samples in
the laboratory using a dissecting microscope
following EPA SOP LG 407 (rev 9, 2015).
Enumeration of Dreissena at each station began in
2003; measurements of shell length commenced in
2007; and measurements of total wet weight (with
shell) commenced in 2012. Other major taxonomic
groups (amphipods, chironomids, oligochaetes,
mollusks) were identified, counted and weighed
after being blotted dry. After counting and
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
weighing by size category, chironomids and
oligochaetes were mounted on slides for
identification. Dreissena were identified to species,
and then divided, counted and weighed by 5-mm
size fractions to the nearest 0.0001 gram after
being blotted dry on absorbent paper. Adult
oligochaetes were identified to species; immatures
were taken to the lowest taxonomic level possible,
usually family. Oligochaete fragments, though
counted, were excluded from density but used for
biomass estimates. Chironomids were identified to
the lowest practical taxonomic level, usually
genus. Other invertebrates were identified to
species, when possible. All unmounted specimens
after identification and weighting were preserved
in a mixture of ethanol (85%), water (10%) and
glycerin (5%).
6 REMOTE SENSING OF
SURFACE CHLOROPHYLL
6.1 DESCRIPTION OF ANALYSIS
In situ measurements of chlorophyll-a
concentration made during the regular surveys (to
be reported separately) were supplemented by
estimates of chlorophyll-a concentration in the
surface waters derived from satellite observations.
Although limited to the surface waters and subject
to interference by clouds, the satellite-derived
estimates provide frequent (as often as daily) and
high spatial resolution (approximately 1 kilometer)
observations throughout the year, making it
possible to discern both spatial and annual
temporal patterns. The satellite-derived estimates
we report here are based on a band-ratio retrieval
algorithm developed using GLNPO monitoring
data (Lesht et al. 2013; 2016) applied to data from
the Sea-viewing Wide Field-of-view (SeaWiFS,
1998-2007) and Moderate resolution imaging
spectroradiometer (MODIS, 2002-present) ocean
color sensors.
6.2 2014 SURFACE CHLOROPHYLL
Monthly averages of the satellite-estimated surface
chlorophyll concentration in each lake are shown
in Figure 2. The images in the upper panels are
based on the by-pixel means of all the satellite
(MODIS) scenes collected during the indicated
month. For lakes Huron, Ontario, Michigan and
Superior, the values plotted in the lower panel line
plot are the monthly averages of chlorophyll
concentration in those main-lake pixels in water
depths exceeding 30 meters. These averages do
not include the major embayments of Saginaw
Bay, Georgian Bay and the North Channel in Lake
Huron and Green Bay in Lake Michigan. The
Lake Erie basin averages include all the pixels
from all depths in each of the three basins but
excluding Lake St. Clair. Black areas in March
and April are regions where no satellite data were
recovered due to ice cover.
In 2014 March-October average surface
chlorophyll-a concentrations in the lower lakes
decreased following the general trophic gradient
from western Lake Erie (9.4 mg/m3) through
Lake Ontario (4.1 mg/m3). In the upper lakes,
surface chlorophyll-a concentration was highest
in Lake Superior (1.3 mg/m3) followed by lakes
Michigan (1.0 mg/m3) and Huron (0.8 mg/m3).
The spatial distributions of chlorophyll-a in the
lakes during the year varied, with the highest
values generally occurring in the late summer
through fall. In Lake Erie, high values were
observed in the western basin beginning in July
that persisted and spread through the central
basin in the following months. In Lake Ontario,
high values began appearing along the northern
and southern coasts in August but concentrations
decreased in October. Flux of high chlorophyll-a
concentrations typical of the major embayments
in lakes Michigan and Huron began to influence
the main lake basins of those lakes in late
Summer. In Lake Superior, higher concentrations
in the western sections of the lake beginning in
September and October account for increases in
lake average concentration late in the year.
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
MAR
MAY
AUG
¦ Erie-W
~ Erie-C
¦ Erie-E
9 Ontario
• Michigan
O Huron
O Superior
MODIS 2014
MAR APR MAY JUN JUL AUG SEP OCT
Figure 2. Monthly average surface chlorophyll-a concentrations estimated from satellite observations. Upper
panels are by-pixel averages of all satellite images collected during the month. The lower panel shows the
average concentrations in the three basins of Lake Erie and in the main basins (excluding major
embayments) of each of the other lakes. Note that the chlorophyll-a concentrations in both the images and the
line plot are depicted on a log scale. Areas shown in black during the spring months are regions where ice-
cover interfered with the chlorophyll-a retrieval. Lake images are not projected nor drawn to scale.
6.3 SURFACE CHLOROPHYLL
TRENDS FROM 1998 TO 2014
Reliable estimates of surface chlorophyll
concentration based on observations made by
satellites date from 1998. Figures 3-7 illustrate
how the monthly average chlorophyll-a
concentration in each of the lakes (each basin for
Lake Erie) has changed from 1998 to 2014. For
each satellite image collected in every month-year
combination, we extracted the satellite
chlorophyll-a estimates from the pixels nearest to
the sampling stations (see Figure 1 for station
locations) and averaged these values. We used the
satellite estimates extracted from the station
locations because they are the closest match to the
other datasets reported here that arise from ship-
borne sampling. Although these average values are
not samples from a continuous function in month-
year space as would be mathematically required
for contour analysis, displaying them in a contour
or isopleth plots helps to visualize changes in the
phytoplankton cycle both during and across years.
LAKE ERIE
The satellite observations reveal some changes in
the annual surface chlorophyll-a concentration
pattern across the years in Lake Erie, primarily in
JULY 2019
PAGE | 8
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
the western and central basins (Figure 3). In the
western basin, increases in chlorophyll-a
concentration in the late summer, possibly
associated with harmful algal blooms have
generally intensified in the years since 2006.
Average concentrations in the spring also have
tended to increase in this time period. In the central
basin, the most prominent change is the narrowing
(in time) and ultimate absence of a summer
concentration minimum between 2008 and 2013
thus creating a single summer peak in chlorophyll
rather than separate peaks in the spring and autumn
Concentrations in the eastern basin are lower than
in the other two basins and although they exhibit
some variability they have been relatively constant.
Oa
Sep
c Aug
VI
~2 Jul
c
1 Jun
I
s May
Apr
Mar
Ocl
Sep
Lake Erie - Regular Monitoring Stations
I I I I I I I 1 I III
7 V
¦
% ¦
-
H I 1 1 1 I 1 I I 1 1 1 f-
M
H 1-
JlWif I*L
— --— 1 <~
T I »
lli
r
8.00
1998 2000 2002 2004 2006 200® 2010 2012 2014
Year
6.00
J
cr
£
4.00 >
Q.
O
c
O
2.00
0.00
Figure 3. Monthly averaged (March-October) surface chlorophyll-a concentrations at station locations in
Lake Erie for the period 1998-2014. The top panel is based on the western basin stations, the middle panel on
the central basin stations, and the bottom panel on the eastern basin stations.
JULY 2019
PAGE | 9
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
LAKE ONTARIO
The seasonal trend in Lake Ontario annual chlorophyll is generally bi-modal with both late spring and
early autumn peaks separated by a summer minimum. The magnitudes of the peaks and the length of the
summer minimum has been variable, but appear to have been increasing since 2007 (Figure 4).
Lake Ontario - Regular Monitoring Stations
OCT
SEP
AUG
JUL
JUN
MAY
APR
MAR
¦
4.50
-
3.75
-
3.00
-
2.25
¦
1.50
0.75
—
0.00
O)
E
Q.
O
o
1998 2000 2002 2004 2006 2008 2010 2012 2014
Year
Figure 4. Monthly averaged (March-October) surface chlorophyll-a concentrations at station locations in
Lake Ontario for the period 1998-2014.
LAKE MICHIGAN
Seasonal trends in Lake Michigan phytoplankton as measured by surface chlorophyll-a concentration
have changed dramatically over the period of observation (Figure 5). Before 2005, chlorophyll-a peaked
during the spring bloom period. Since about 2005, however, the spring chlorophyll-a peak has been
absent and the annual average concentration has steadily declined. First reported by Lesht and Wortman
(200 7). the absence of the spring bloom has been most often attributed to direct filtration by dreissenid
mussels (Kerfoot et al. 2010). although subsequent research has suggested the potential importance of
other factors such as nutrient interception by nearshore populations of dreissenid mussels and
meteorological influence on phosphorus dynamics (Barbiero et al. 2018b).
Lake Michigan - Regular Monitoring Stations
OCT-
SEP -
AUG -
JUL-
JUN -j
MAY-
APR -
MAR -
I 2.00
1.50,
_i i i i i i i i i i i i i i i i i
1998 2000 2002 2004 2006 2008 2010 2012 2014
Year
i
1.00 S-
0.50
0.00
O
Figure 5. Monthly averaged (March-October) surface chlorophyll-a concentrations at station locations in
Lake Michigan for the period 1998-2014.
JULY 2019
PAGE | 10
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
LAKE HURON
The change in the seasonal chlorophyll-a pattern in Lake Huron (Figure 6) is very similar to that
observed in Lake Michigan. The well-defined spring peak in surface chlorophyll-a concentration found
prior to 2004 is absent in subsequent years. The similarity between the changes in lakes Huron and
Michigan is of particular interest because the population of dreissenid mussels in Lake Huron is much
lower than in Lake Michigan suggesting that the decline in the spring bloom in Lake Huron may result
from different or from a combination of causes (Barbiero et al. 2018b). Of all the Great Lakes, Lake
Huron has the lowest overall chlorophyll concentration
Lake Huron - Regular Monitoring Stations
12.00
1.50_
E
cs
E.
1.00?,
sz
Q.
O
O
0.50
0.00
O
1998
2000
2002 2004
2006
Year
2008
2010
2012 2014
Figure 6. Monthly averaged (March-October) surface chlorophyll-a concentrations at station locations in
Lake Huron for the period 1998-2014.
LAKE SUPERIOR
Although not as dramatic as the changes in lakes Huron and Michigan, Lake Superior also appears to
have experienced a decline in spring peak chlorophyll-a since 2005 (Figure 7). Lake Superior
chlorophyll-a concentrations peaked regularly during April-May prior to 2005, but since then the highest
concentrations have been observed during the fall. Because dreissenid mussels have not colonized Lake
Superior (except for some isolated coastal areas) this apparent chlorophyll-a decline must result from
some other mechanism.
Lake Superior - Regular Monitoring Stations
OCT-
SEP -
AUG -
£ JUL
JUN -
MAY
APR -
MAR
ir4
1998 2000 2002 2004
2006 2008
Year
2010 2012
2014
12.00
1.50,
u
~0>
1.00 >.
0.50
0.00
O
Figure 7. Monthly averaged (March-October) surface chlorophyll-a concentrations at station locations in
Lake Superior for the period 1998-2014.
JULY 2019
PAGE | 11
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
7 PHYTOPLANKTON
7.1 COMMUNITY COMPOSITION IN
2014
SPRING
During spring, a total of 198 phytoplankton taxa
was found. Total phytoplankton sample
biovolumes across the lakes ranged from
approximately 5 x 104 (.inrVinL in Lake Superior to
approximately 1 x 106 (.inrVinL in the central basin
of Lake Erie (Figure 8). Lakes Superior, Michigan
and Huron phytoplankton communities consisted
mainly of centric and pennate diatoms,
cryptophytes and dinoflagellates in spring,
although the proportions of each group varied
among the lakes. In Lake Erie, the western basin
of Lake Erie phytoplankton community was
dominated by centric and pennate diatoms in
spring. The central basin and eastern basin
phytoplankton communities had high levels of
centric diatoms and dinoflagellates in spring. Lake
Ontario's spring phytoplankton community was
dominated by centric diatoms, dinoflagellates and
cryptophytes.
SUMMER
During summer, a total of 223 phytoplankton taxa
was found. Summer phytoplankton communities
in lakes Superior, Michigan and Huron consisted
mainly of centric and pennate diatoms,
dinoflagellates and cryptophytes (particularly in
Lake Huron) (Figure 12).The western and central
basin of Lake Erie phytoplankton communities
were dominated by cyanobacteria in summer,
while the eastern basin had high pennate diatom
biovolumes. Lake Ontario's phytoplankton
community was dominated by pennate diatoms,
cryptophytes and dinoflagellates in summer.
7.2 COMMUNITY COMPOSITION
FROM 2001 TO 2014
Hundreds of unique taxa were encountered in the
2001-2014 phytoplankton dataset. The
assemblages comprised centric diatoms, pennate
diatoms, chrysophytes, chlorophytes,
cryptomonads, cyanophytes, euglenoids,
dinoflagellates and rare, unknown entities. Spring
biovolumes were highest in Lake Erie (Figure 8).
and dominated by the centric diatom (Figure 9)
Aulacoseira islcindicci, consistent with recent
findings of blooms of this taxon (Reavie et al.
2016; Barbiero et al. 2006). Summer biovolume
tended to be highest for the cyanophyte
Microcystis aeruginosa in Lake Erie's western
basin, but there were also some high abundances
of diatoms, dinoflagellates and cryptophytes.
These data illustrate how some taxa with low
numeric abundance and large cell size (e.g., the
dinoflagellate Peridinium in spring Lake Ontario)
can comprise an important component of lake
productivity.
Overall, the dominant phytoplankton in spring
tended to be opportunistic diatom taxa
(Aulacoseira, Stephanodiscus) which make use of
abundant nutrients such as phosphorus and silica
before declining due to nutrient limitation later in
the year. Lake Erie had the highest biovolume of
dominant taxa; algal biovolume overall was
relatively low in the upper lakes (Superior, Huron,
Michigan; Figure 8). In the summer, the upper
lakes were dominated by diatoms such as Synedra
and Cyclotella and in Huron by large-celled
dinoflagellates.
JULY 2019
PAGE | 12
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
7.3 COMMUNITY TRENDS FROM
2001 TO 2014
Temporal changes in phytoplankton abundance are
shown through histograms that summarize within-
lake and sometimes within-basin averages
(Figures 9-12). In the 14 years of data presented,
certain phytoplankton taxa in certain lake basins
have flourished and other taxa have declined.
These changes are attributed to food web shifts
and changes in water quality. Likely reasons for
these changes include selective grazing by
herbivores, changes in nutrient concentrations and
availability (e.g., Lake Erie) and climate-related
changes in physical properties of the lakes such as
extended ice-free seasons and enhanced summer
stratification. These mechanisms are discussed in
greater detail in Reavie et ctl. (2014. 2017).
LAKE ERIE (Figures 9. 11)
Lake Erie's western basin was typically dominated
by centric diatoms in the spring (e.g., Dicitoma,
Aiilctcoseirct) although recently large-celled
pennate diatoms (Surirella) and euglenoids
(Phacus) have also comprised a significant portion
of the assemblage. The last decade exhibited large
fluctuations in algal abundance and composition in
the spring, but summer has seen a persistent
increase in cyanophytes (dominated by
Aphctnocctpsct and Microcystis). There is evidence
that summer algal biovolume is increasing, but
year-to-year fluctuations are unpredictable with
especially high abundance in 2011.
Spring in Lake Erie's central basin was
overwhelmingly dominated by the filamentous
centric diatom A islctndicct. Spring diatom
abundances remain high in the basin, but data
suggest a decline since the 2006 peak. Summer
assemblages reveal increases in algal density and
biovolume, particularly for cyanophytes (e.g.,
Aphctnocctpsct and Aphctnizomenon) and a periodic
high abundance of pennate diatoms (Frctgilctrict
crotonensis).
Lake Erie's eastern basin was similarly dominated
by A. islctndicct in the spring, but little change was
observed for the last 10 years. Summer data
indicated an increase in biovolume in 2008 and
2009, particularly by cyanophytes (e.g.,
Aphctnocctpsct) and pennate diatoms (Frctgilctrict
crotonensis).
TAKE ONTARIO (Figures 10. 12)
While not easily apparent in the histogram, overall
Lake Ontario phytoplankton density and
biovolume increased over the last 14 years, as
detected by Kendall rank correlation testing (P <
0.05). During that time, the relative density of
dinoflagellates (Peridinium) increased in the
spring. Summer cyanophytes (largely
Aphctnocctpsct) increased in number but the
assemblage is dominated by pennate diatoms (e.g.,
Frctgilctrict crotonenis), cryptophytes
{Cryptomoncts) and dinoflagellates (Cercitium
hinindinellct).
TAKE MICHIGAN (Figures 10. 12)
Cell density in Lake Michigan is dominated by
cyanobacteria, but in terms of biovolume, spring
in the northern basin is dominated by
dinoflagellates (e.g., Gymnodinium helveticum)
and centric diatoms while the southern basin has
large amounts of cryptophytes. In the summer,
Lake Michigan is dominated by diatoms (e.g.,
Cyclotellct comtct, Frctgilctrict crotonensis). There
has been a notable decline in spring biovolume in
the southern basin since 2001 and since
approximately 2008 there has been a greater
relative dominance by cryptophytes (Crvptomoncis
and Rhodomoncts). The major period of algal
decline occurred in spring 2002 and 2003 in the
northern basin and 2005 in the southern basin. A
similar decline has not been observed for summer
phytoplankton; summer algal biovolume has been
variable.
TAKE HURON (Figures 10. 12)
Cyanophytes (e.g., Aphctnizomenon,
Aphctnocctpsct) dominate Lake Huron's
phytoplankton in terms of cell densities, but in
terms of biovolume Lake Huron is dominated by
diatoms (e.g., Cyclotellct), cryptophytes and
chrysophytes in the spring, and by diatoms (e.g.,
Tctbellctrict, Cyclotellct), chrysophytes and
dinoflagellates (e.g., Peridinium) in the summer.
JULY 2019
PAGE | 13
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Since 2001, Lake Huron has seen a decline in
spring biovolume with the major transition
occurring from 2002 to 2003 with a significant
drop in diatom abundance. Summer data reveal a
similar, less dramatic decadal decline with the
main drop occurring from 2001 to 2002, overall
suggesting that the major shift in Lake Huron's
phytoplankton community occurred predominantly
between the spring and summer sampling seasons
in 2002. Since approximately 2003, the data
suggest some recovery in algal abundance in the
northern basin and in the spring in the southern
basin.
LAKE SUPERIOR (Figures 10. 12)
Phytoplankton biovolume in Lake Superior is
dominated by diatoms, chrysophytes, cryptophytes
and dinoflagellates in the spring, and more so by
diatoms in the summer. Over the 14 years, little
overall change in algal abundance and
composition is evident in the histograms, although
trend analysis (Kruskal-Wallace, P < 0.05)
detected significant increases in overall abundance
in the spring and a decrease in summer abundance.
~
Centric Diatoms
¦
Pennate Diatoms
~
Chlorophytes
¦
Chrysophytes
¦
Cryptophytes
Cyanophytes
¦
Dinoflagellates
~
Other
Spring
100
50
8e+5
=3 4e+5 -
*
ln-__
ER
ON
Ml
HU
SU
W
Summer
"ILLM ¦ ¦ = ¦
2.0e+6
1.6e+6
1.2e+6
ft 8.0e+5
4.0e+5
0.0
ER
ON
Ml
HU
SU
W
Figure 8. Phytoplankton biovolume (bottom panels) and percent biovolume (top panels), by major taxonomic
group, for spring and summer, 2014.
JULY 2019
PAGE | 14
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Erie, Central Basin
I
f
4
i
Centric Diatoms
Pennate Diatoms
Chlorophytes
Chrysophytes
Cryptophytes
Cyanophytes
Dinoflagellates
I 1 Other
Erie, Eastern Basin
100
50
0
3e+6
2e+6
u
2002 2004 2006 2008 2010 2012 2014
Erie, Western Basin
100 -
50 -
o -
3e+6 -
I
Loffl
2002 2004 2006 2008 2010 2012 2014
2002 2004 2006 2008 2010 2012 2014
Figure 9. Phytoplankton biovolume (bottom panels) and percent biovolume (top panels), by major taxonomic
group, in Lake Erie for spring 2001-2014. Error bars represent one standard error.
JULY 2019
PAGE | 15
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Ontario
4.8e+5
4.0e+5
2.4e+5
1.6e+5
8.0e+4
2002 2004 2006 2008 2010 2012 2014
Michigan
100
50
ii
x
T
n
—1
_
1
¦
_
—
Centric Diatoms
Pennate Diatoms
ZD Chlorophytes
H Chrysophytes
H Cryptophytes
ZD Cyanophytes
Dinoflagellates
I 1 Other
Huron
100
50
4e+5
3e+5
2002 2004 2006 2008 2010 2012 2014
Superior
8e+4 -
2002 2004 2006 2008 2010 2012 2014
2002 2004 2006 2008 2010 2012 2014
Figure 10. Phytoplankton biovolume (bottom panels) and percent biovolume (top panels), by major
taxonomic group, in lakes Ontario, Huron, Michigan and Superior for spring 2001-2014. Error bars
represent one standard error.
JULY 2019
PAGE | 16
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Erie, Western Basin
LL
I
Centric Diatoms
Pennate Diatoms
Chlorophytes
Chrysophytes
Cryptophytes
Cyanophytes
Dinoflagellates
I 1 Other
Erie, Central Basin
100
50
2e+6
2e+6 -
1e+6 -
5e+5
==X
2002 2004 2006 2008 2010 2012 2014
Erie, Eastern Basin
e+6 -
5e+5 -
2002 2004 2006 2008 2010 2012 2014
2002 2004 2006 2008 2010 2012 2014
Figure 11. Phytoplankton biovolume (bottom panels) and percent biovolume (top panels), by major
taxonomic group, in Lake Erie for summer 2001-2014. Error bars represent one standard error.
JULY 2019
PAGE | 17
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Centric Diatoms
Pennate Diatoms
Chlorophytes
Chrysophytes
Cryptophytes
Cyanophytes
Dinoflagellates
I I Other
Michigan
100
50 -
0 -
5.0e+5 -
2.5e+5
Ontario
o.o
i
Fee
1.5e+6
1.3e+6
1.0e+6 -
£ 7.5e+5 •
5.0e+5
2.5e+5 -
0.0
2002 2004 2006 2008 2010 2012 2014
Huron
100
2.5e+5
— —
I
2002 2004 2006 2008 2010 2012 2014
Superior
2.5e+5 -
2002 2004 2006 2008 2010 2012 2014
2002 2004 2006 2008 2010 2012 2014
Figure 12. Phytoplankton biovolume (bottom panels) and percent biovolume (top panels), by major
taxonomic group, in lakes Ontario, Huron, Michigan and Superior for summer 2001-2014. Error bars
represent one standard error. No samples were analyzed for Lake Ontario in 2006.
JULY 2019
PAGE | 18
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
8 ZOOPLANKTON
8.1 COMMUNITY COMPOSITION IN 2014
Zooplankton communities in 2014 differed from lake to lake, in size and composition, with differences
most pronounced in summer (Figure 13).
Summer
¦
Bosminids
¦
Other Cladocerans
¦
Daphnia
¦
Predatory Cladocerans
~
Cyclopoids
Calanoids
¦
Limnocalanus
100
50 -
Spring
ro
E
CO
o
E
in
o
1
Q
100
50 -
0
50 -
40 -
30 -
20 -
10
0
CD
£
(f)
(f)
CT5
£
o
bo
o
-i—¦
CD
E
_D
150 -
100 -
50 -
ER
ON
Ml
HU
SU
ER
ON
Ml
HU
SU
W
W
Figure 13. Crustacean volumetric biomass (bottom panels) and percent volumetric biomass (top panels), by
major taxonomic group, for spring and summer, 2014.
SPRING
Spring communities in lakes Superior, Michigan
and Huron were dominated by calanoid copepods,
while cyclopoid copepods and copepodites
contributed a larger proportion of the biomass in
lakes Erie and Ontario. Cladocerans were limited
for the most part to the western basin of Lake Erie.
Total crustacean biomass (excluding Mysis) was
lower in the spring than in the summer.
SUMMER
Broadly correlated with lake productivity, summer
zooplankton volumetric biomass was highest in
the western and central basins of Lake Erie,
followed by the eastern basin of Lake Erie and
Lake Ontario, with the lowest volumetric biomass
seen in Lake Superior. Cladocerans and
cyclopoids were more common in the more
productive lakes Erie and Ontario whereas
calanoids dominated in lakes Michigan, Huron and
Superior, consistent with a greater prevalence of
cladocerans and cyclopoids in more productive
systems. Seasonal differences in biomass between
April and August also followed this pattern, with
the greatest increases in biomass between the two
sampling dates being seen in lakes Erie and
Ontario. Communities in lakes Huron and
Michigan were very similar, and exhibited
somewhat higher levels of volumetric biomass as
well as a greater contribution from non-
Limnoccilciniis calanoid copepods than was seen in
Lake Superior.
NEW INTRODUCED SPECIES
A new zooplankton introduction was detected in
the Great Lakes in a sample collected in Lake Erie
JULY 2019
PAGE | 19
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
in 2014 (Connolly et al. 2017). marking the first
established population of a non-indigenous
zooplankton species in the Great Lakes since
Hemimysis anomala was found in lakes Michigan
and Ontario in 2006 (Pothoven et al. 2007; Walsh
et al. 2010). The zooplankter, Thermocyclops
crassns, is a small Eurasian cyclopoid copepod
which was found in the western basin of Lake Erie
near the entry of the Detroit River into Lake Erie -
a shallow, warm, and eutrophic habitat, similar to
its reported native habitats (Connolly et al. 2017).
Its abundance is extremely low relative to the most
similar native copepod species Mesocvclops edctx
(1/m3, compared to 1,000/m3). Thermocyclops
crctssus had previously been reported from Lake
Champlain in 1991, in the shallow, eutrophic
Missisquoi Bay (Duchovnav et al. 1992). The
vector for this new introduction has not been
determined. According to the U.S. Fish and
Wildlife Service, the ecosystem risk from
Thermocyclops crctssus is uncertain because past
introductions have not been studied to determine
whether impacts occurred (U.S. FWS 2016).
8.2 COMMUNITY COMPOSITION
TRENDS FROM 1997 TO 2014
SPRING
Little interannual difference in spring volumetric
biomass was seen in Lake Superior, where
calanoids dominated in all years (Figure 14).
Cyclopoid copepods contributed less volumetric
biomass in lakes Michigan and Huron than in
lakes Erie and Ontario, and were more prevalent in
the early years of the time series, with some
exceptions (2011 and 2013 in Lake Michigan,
2013 in Lake Huron). As noted, a distinct
reduction in biomass was seen in Lake Huron in
2004; a general but less pronounced trend of
decreasing biomass was also seen in Lake
Michigan. In general, communities in these two
lakes exhibited substantial similarities (Barbiero et
al. 2018b).
Spring biomass in the western basin of Lake Erie
exhibited a notable decrease in 2004 (Figure 14).
This corresponded with a coincident decrease in
Lake Huron, and most likely represented a
reduction in zooplankters washing into the western
basin of Lake Erie from the upstream Lake Huron.
The central basin of Lake Erie exhibited somewhat
increased biomass in the later years of the time
series, with cladocerans contributing an increased
proportion of the biomass during this period.
While volumetric biomass levels in the eastern
basin were substantially lower than those seen in
the central basin, interannual trends were similar
in the two basins.
Lake Ontario exhibited an increase in calanoid
volumetric biomass over time, especially in the
2005-2011 time period. A return to more cyclopoid
biomass is seen in recent years.
JULY 2019
PAGE | 20
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Bosminids
Other Cladocerans
I I Daphnia
Predatory Cladocerans
I I Cyclopoids
I I Calanoids
i m Limnocalanus
Erie, Western Basin
20 -
10
I
a
1998 2000 2002 2004 2006 2008 2010 2012 2014
Erie, Central Basin
100
50
0
50 -
CD
(/)
(f)
CT5
£
o
in
o
-i—¦
0
E
_D
£
40 -
30
20
10 -
X
I
A
i
X
1998 2000 2002 2004 2006 2008 2010 2012 2014
Erie, Eastern Basin
100
50
0
15
10
5
Ontario
1998 2000 2002 2004 2006 2008 2010 2012 2014
100
50
0
30 -
Michigan
m
20 -
10 -
1998 2000 2002 2004 2006 2008 2010 2012 2014
Huron
100
50 -
0 -
50 -
40
30
20 -
10 -
A
1998 2000 2002 2004 2006 2008 2010 2012 2014
Superior
100
1998 2000 2002 2004 2006 2008 2010 2012 2014
1998 2000 2002 2004 2006 2008 2010 2012 2014
Figure 14. Crustacean volumetric biomass (bottom panels) and percent volumetric biomass (top panels), by
major taxonomic group, for spring 1998-2014. Error bars represent one standard error. No samples were
analyzed for spring in 2000.
JULY 2019
PAGE | 21
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
SUMMER
Summer Lake Superior communities have been
dominated by calanoid copepods, notably
Limnocalanus, with little evidence of change over
time (Figure 15). Summer crustacean
communities in lakes Michigan and Huron have
exhibited reductions in cladoceran biomass and
shifts towards greater dominance by calanoid
copepods, with strong similarities between the two
lakes (Barbiero et al. 2009. 2013. 2018b). This
trend has continued through 2014. Total
volumetric biomass in Lake Huron has been
notably consistent since 2005, with 2010 and 2012
being anomalous years of relatively high
cladoceran biomass. While the reduction in
cladocerans has not been as pronounced in Lake
Michigan, an increase in Limnocalanus biomass,
seen most consistently in the northern basin, has
contributed to the relative shift towards greater
calanoid dominance.
Summer crustacean communities in the western
basin of Lake Erie showed a high degree of
interannual variability, with no overall trend
(Figure 15). While volumetric biomass tended to
be higher than in other areas of the Great Lakes,
the lowest volumetric biomass recorded in our
time series (2001) was also found in the western
basin. Substantial interannual variability was also
found in the other basins of Lake Erie, although
not to the extent seen in the western basin.
Calanoid copepods contributed a higher proportion
of biomass to the central and eastern basins, while
Bvthotrephes volumetric biomass in these basins
tended to be substantially higher than in both the
western basin and the other lakes.
Beginning in 2004, communities in Lake Ontario
showed a clear shift towards proportionally less
cyclopoid biomass and more calanoid biomass.
This represents a shift in the Lake Ontario summer
crustacean community from an assemblage
dominated by Diacyclops thomasi, Daphnia
retrocurva and bosminids, and with Cercopagis
pengoi (which invaded the lake in 1998,
Makarewicz et al. 2001) the dominant predatory
cladoceran, to one characterized by reduced
cyclopoid biomass, a more varied predatory
cladoceran community, and increased biomass of
calanoid copepods (Barbiero et al. 2014; Rudstam
et al. 2015). A further shift from 2008-2011
towards increased biomass of Leptodiaptomns
sicilis, Bvthotrephes longimanus and Daphnia
mendotae was also noted. More recent years have
seen a reversion towards the Cercopagis, D.
retrocurva, D. thomasi community. Vertebrate
predation may be a main driver in structuring this
crustacean community, with lower predation
permitting the development of Bvthotrephes
populations, which in turn suppressed D. retrocurva
and promoted D. mendotae (Barbiero et al. 2014;
Rudstam et al. 2015). If so, then current levels of
vertebrate predation pressure could be oscillating
around the alewife abundance that can suppress
Bvthotrephes populations, resulting in interannual
shifts between the two community types.
JULY 2019
PAGE | 22
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Erie, Western Basin
100 =— —
300
200
I Bosmimds
I Other Cladocerans
I Daphnia
Predatory Cladocerans
I Cyclopoids
I Calanoids
Limnocalanus
Ontario
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w
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o
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E
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Erie, Central Basin
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|I
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1998 2000 2002 2004 2006 2008 2010 2012 2014
Erie, Eastern Basin
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30
0
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Michigan
---
IT
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ft
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Huron
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d
.
.
100
50
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Superior
002 2004 2006 2008 2010 2012 2014
1998 2000 2002 2004 2006 2008 2010 2012 2014
1998 2000 2002 2004 2006 2008 2010 2012 2014
Figure 15. Crustacean volumetric biomass (bottom panels) and percent volumetric biomass (top panels), by
major taxonomic group, for summer 1997-2014. Error bars represent one standard error.
JULY 2019
PAGE | 23
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
9 MYSIS
9.1 ABUNDANCE IN 2014
Mysis diluvicma occurs in all five of the Great
Lakes but densities vary substantially among
lakes. Mysis is a long-lived crustacean
zooplankton species that reproduces after two
years and areal density (#/m2) is therefore fairly
similar in spring and summer. In Lake Erie, the
species is rare and was only found in the deeper
Eastern basin in the spring. In the other lakes,
densities ranged from around 40/m2 (Huron), 140
to 200/m2 in lakes Michigan and Superior and 350
to 450/m2 in Lake Ontario. Areal biomass (spring-
summer) was also lower in Lake Huron (14-59 g
DW/m2) than in the other three lakes (Michigan
179-348 g DW/m2, Superior 350-416 g DW/m2,
Ontario 361-724 g DW/m2). The number of
stations sampled per lake ranged from 1 to 8 in
spring and from 1 to 9 in summer.
In 2014, mysid biomass was <1% of the total
crustacean biomass in Lake Erie, <4% in Lake
Huron, 14-18% in Lake Michigan, 17-25% in
Lake Superior and 21-48% in Lake Ontario, with
the higher values representing spring conditions.
9.2 POPULATION TRENDS FROM
2006 TO 2016
Annual trends are presented for both spring and
summer in the four deeper lakes (Figure 16).
Because mysid biomass is depth-dependent (fewer
mysids present in water shallower than 100
meters), and spring values tend to be lower than
summer values, we analyzed time trends including
station depth and season as covariates. This
analysis has been completed for the time period
2006/2007 to 2016 (Jude et al. 2018). Sampling
began in 2006 in lakes Huron, Michigan and
Ontario and in 2007 in lakes Superior and Erie.
Mysid areal biomass showed no significant time
trends in lakes Huron, Michigan and Ontario
although it did increase significantly during this
time period in Lake Superior. Over the whole time
period 2006/2007 to 2016, mysid biomass was
significantly lower in Lake Huron than the other
three deep lakes, significantly lower in Michigan
than in Ontario with Superior not significantly
different from either Michigan or Ontario (Figure
17). The proportion of crustacean biomass
represented by mysids was on average for these
years 12-18% in Lake Michigan, 14-18% in Lake
Superior, 13-30% in Lake Ontario and <3% in
lakes Huron and Erie. Lake Erie has shown
consistently low mysid biomass throughout the
time period.
JULY 2019
PAGE | 24
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Michigan
Spring
Summer
luMU
o 400
a?
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
1400 -
1200 -
1000 -
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
T Huron
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2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Figure 16. Mysis diluviana areal density (mg DW/m2) trends from 2006-2016. Averages are based on stations
deeper than 30 meters. (*) signifies years where Mysis were not sampled during one season: Lake Erie (spring
2007,2009,2010 and 2013; summer 2011 and 2014) and Lake Ontario (summer 2006). (**) signifies years
where Mysis were not sampled during either season: Lake Erie (2006,2016) and Lake Superior (2006). Error
bars represent one standard error. Y-axis scales are consistent across graphs with the exception of Lake Erie.
JULY 2019
PAGE | 25
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Q
CD
CO
CO
CC
E
o
in
900
800 -
700 -
600 -
500 -
400 -
_ 300 -
CC
0
< 200 H
100
0
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sum
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Erie
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Ontario Michigan Huron Superior
Figure 17. Mysis diluviana areal biomass (mgDW/m2) for stations deeper than 30 meters, averaged across
years for the spring and summer surveys (2006/7-2016). Error bars represent one standard error.
Although the number of stations sampled is small
in some years, these patterns are generally similar
to the more extensive surveys available. For
example, more extensive surveys of Lake Ontario
mysids in 2013 by Cornell, USEPA, and the
Department of Fisheries and Oceans - Canada
(DFO) also shows a strong decline in mysids in
2013 and an increase in 2014 (Holda et al. 2019).
However, the peak in Lake Ontario in 2008 is
likely an artifact of the small sample size as 2008
had only marginally higher average biomass than
surrounding years in the DFO data (Johannssonet
al. 2011). Reported mysid densities from Lake
Michigan for this time period is limited. For two
stations in southeastern Lake Michigan, data from
National Oceanic and Atmospheric
Administration's Great Lakes Environmental
Research Laboratory show densities of 100-
150/m2 (Pothovcn and Vanderploeg 2017) which
is similar to averages in the GLNPO data (104/m2
- spring, 146/m2 - summer, Jude et al. 2018).
JULY 2019
PAGE | 26
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
10 BENTHOS
10.1 COMMUNITY COMPOSITION IN 2
The composition of benthic communities in
summer 2014 changed along a productivity/depth
gradient, from shallow and productive Lake Erie,
Green Bay, and Saginaw Bay, characterized by a
high percentage of oligochaetes, high abundance
of Dreissena (zebra and quagga mussels) and no
Diporeici, to deep Lake Superior characterized by
low densities of oligochaete species intolerant to
organic pollution, abundant Diporeici, and absence
of Dreissena.
The highest total wet biomass of benthos in 2014
was found in Lake Ontario, followed by, in order
of decreasing biomass, Lake Erie, Michigan,
Huron and Superior. The largest contributor of
biomass in all lakes except Superior in 2014 was
the quagga mussel (wet weight with shells); the
highest lakewide average biomass of quagga
mussels was found in Lake Ontario (1008 g/m2,
83.8% of total benthos biomass), followed by
lakes Erie (784 g/m2, 98.7%) and Michigan (656
g/m2, 99.3%). The lowest biomass of Dreissena
was found in Lake Huron (125 g/m2, 98.7%).
Excluding Dreissena, the highest areal benthos
biomass was found in Lake Erie. In all lakes, non-
dreissenid communities were dominated by
oligochaetes (Figure 18) except for Lake Superior
where Diporeia dominated benthos density and
biomass in both shallow (<70 meter) and deep (>
70 meter) zones. Diporeia was also a co-dominant
species in the deep offshore sediments of lakes
Michigan and Huron. In Lake Erie, the burrowing
mayfly Hexagenia spp. was found only in the
western basin but comprised 12% of total non-
dreissenid biomass in that basin.
JULY 2019
PAGE | 27
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Shallow
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03
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Figure 18. Absolute and percent areal biomass of benthos by major taxonomic group excluding Dreissena
spp. (bottom and middle panels) and areal biomass of Dreissena spp. (top panels) at shallow (< 70 meters) and
deep (> 70 meters) stations in 2014. The asterisk (*) indicates that Lake Erie has no deep stations. Error bars
represent one standard error.
JULY 2019
PAGE | 28
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
10.2 COMMUNITY COMPOSITION TRENDS FROM 1997 TO 2014
Trends in benthos communities from 1997 to 2014
are presented in Figures 19 and 20. The largest
changes over the last 17 years were found in the
profundal communities (> 70 meters) of lakes
invaded by quagga mussels (all lakes except for
Lake Superior): profundal species, excluding
quagga mussels, decreased in abundance, and their
depth distribution shifted deeper compared to the
beginning of the time series. Diporeia, formerly
dominant in lakes Michigan, Huron and Ontario,
has largely disappeared from stations <70 meters
and is now replaced by quagga mussels. A large
decline was also found in Sphaeriidae. From
1997-2014, the abundance of littoral and
sublittoral groups (especially Naididae and
Turbellaria) increased, and quagga mussel density
and depth distribution increased significantly in all
invaded lakes (Burlakova et al. 2018a).
Erie
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1998 2000 2002 2004 2006 2008 2010 2012 2014
Figure 19. Trends in benthos areal density (bottom panels) and percent areal density (top panels) of major
taxonomic groups in Great Lakes (1997-2014) < 70 meters depth. These values exclude Dreissena spp. Error
bars represent one standard error.
JULY 2019
PAGE | 29
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
Ontario
o
o
o
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-)—I
CO
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0
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0
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Michigan
I
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^ X
Huron
100
50
0
4.0
3.5
3.0
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0.5
0.0
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0.0
I
I
X
xl
X
1998 2000 2002 2004 2006 2008 2010 2012 2014
Superior
I
QjjlT.TplX,
III
T
1998 2000 2002 2004 2006 2008 2010 2012 2014
1998 2000 2002 2004 2006 2008 2010 2012 2014
Figure 20. Trends in benthos areal density (bottom panels) and percent areal density (top panels) of major
taxonomic groups in Great Lakes (1997-2014) > 70 meters depth. These values exclude Dreissena spp. Error
bars represent one standard error.
LAKE ERIE
The total benthic density increased between 2000
and 2010, mainly due to increased Dreissena and
Oligochaeta abundances, and then declined,
returning to total densities observed in the late
1990s. Among Oligochaeta, the density of organic
pollution-intolerant Lumbriculidae decreased in
the eastern basin, while pollution-tolerant
Tubificidae and Naididae were increasing
lakewide. As a result, total Oligochaeta density
increased at most stations, with the strongest
trends observed in western and central basins.
Abundance of Hirudinea and Turbellaria
increased, but no significant lakewide trends were
found for Chironomidae, Trichoptera, Amphipoda,
Isopoda, and Sphaeriidae. No Diporeia have been
collected in the lake since the beginning of the
monitoring program in 1997.
TAKE ONTARIO
Densities of Oligochaeta increased in the
profundal zone, largely due to an increase in
Lumbriculidae. Observed declines in Diporeia
were most dramatic in the profundal zone, as their
decline at shallower depths had begun before
initiation of our benthic sampling program in 1997
JULY 2019
PAGE | 30
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
(Watkins et al. 2013). Diporeia densities in the
profundal zone declined more than 100-fold and
the species almost disappeared from monitoring
stations. Sphaeriidae decreased lakewide, and
particularly at shallow depths. Densities of quagga
mussels increased at all depths, but most
dramatically in the profundal zone. Due to the
decline in Diporeia, total profundal benthos
decreased; however, when both quagga mussels
and Diporeia were excluded from the analysis, the
trend was positive due to increases in Oligochaeta.
LAKE MICHIGAN
Densities of Diporeia declined dramatically
lakewide from 1997-2014. The most abrupt
declines were recorded between 30 and 60 meter
depths where Diporeia densities have plummeted
from the end of 1990s to mid-2000s (Figures 19.
20). In 2014, Diporeia were not present at any of
the < 70 meter stations; however, densities at the
profundal zone stations have remained relatively
stable from 2004 to 2014. Sphaeriidae densities
declined lakewide, with the largest losses at
shallow (<70 meter) depths. Similar declines were
found in Heterotrissocladius spp., particularly at
shallow depths (<70 meters). Quagga mussel
densities increased lakewide including at the
deepest stations (128-250 meters) where they
were first recorded in 2008. Only one station in the
southern basin (MI18M, 160 meters) had yet to be
invaded by Dreissena in 2014. The highest
densities of Dreissena (up to 50,000/m2) were
observed between 40-120 meters, with low
abundance deeper than 120 meters. Following the
large declines in Diporeia (from 52% to 3% of
total density), the benthic community of Lake
Michigan is currently dominated by quagga
mussels (80% of total density). Total lakewide
benthic densities increased at depths < 70 meters,
but non-dreissenid benthos decreased significantly
overall and progressively so with increasing
depths, mostly due to the large declines in
previously dominant Diporeia and declines in
Sphaeriidae (Figures 19. 20).
The percent of Oligochaeta comprising the total
benthos abundance increased lakewide (Figures
18. 19). In 2014, quagga mussel densities were
still increasing and were found at 8 of 11 stations;
the three long-term monitoring stations not yet
invaded are all > 70 meters deep. The proportion
of Diporeia densities that comprised the total
benthos density declined from 58% in 1998-2002
to 5% in 2010-2014 and was replaced by quagga
mussels (36% of total benthos density in 2010-
2014) and Tubificidae (30% of total benthos
density in 2010-2014). Sphaeriidae densities
declined lakewide, especially at stations < 70
meters deep. Among Chironomidae, there was a
significant loss in the formerly dominant
deepwater species Heterotrissocladius spp. Due to
the significant decrease in Diporeia, densities of
native profundal benthos declined (Figure 20).
LAKE SUPERIOR
While there was a significant increase in densities
of deepwater Enchytraeidae and Turbellaria,
changes in all other taxa were small and
insignificant. Dreissena, although established in
the Duluth-Superior harbor and encountered on
shipwrecks and rocky substrates around the
Apostle Islands National Lakeshore, was not
collected at our long-term monitoring stations. No
changes in the dominant species complex were
detected in Lake Superior since the beginning of
the monitoring program in 1997.
LAKE HURON
JULY 2019
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
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. The University of Wisconsin Press, Wisconsin.
Barbiero, R.P., Lesht, B.M., Hinchey, E.K., Nettesheim, T.G., 2018a. A brief history of the US EPA Great
Lakes National Program Office's water quality survey. J. Great Lakes Res. 44, 539-546.
Barbiero, R.P., Lesht, B.M., Warren, G.J., 2014. Recent changes in the offshore crustacean zooplankton
community of Lake Ontario. J. Great Lakes Res. 40, 898-910.
Barbiero, R.P., Lesht, B.M., Warren, G.J., Rudstam, L.G., Watkins, J.M., Reavie, E.D., Kovalenko, K.E.,
Karatayev, A.Y., 2018b. A comparative examination of recent changes in nutrients and lower food
web structure in Lake Michigan and Lake Huron. J. Great Lakes Res. 44, 573-589.
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benthos, in: Riley, S.C. (Ed.), The State of Lake Huron in 2010. Great Lakes Fishery Commission
Special Publication, pp. 10-20.
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communities and nutrient dynamics in the eastern basin of Lake Erie since the invasion of Dreissena
spp. Can. J. Fish. Aquat. Sci. 63, 1549-1563.
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benthic community of the Laurentian Great Lakes: Analysis of spatial gradients and temporal trends
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Evans, M.S., 1985. The morphology of Dciphnici pulicctrict, a species newly dominating the offshore
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sensitivity and light avoidance by Mysis relicta. Can. J. Fish. Aquat. Sci. 56, 311-322.
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GREAT LAKES BIOLOGY MONITORING PROGRAM TECHNICAL REPORT
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L.G., 2019. Status ofMysis diluvictna in Lake Ontario in 2013: Lower abundance but higher fecundity
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Laurentian Great Lakes. Ohio Biol. Surv. Bull. New Ser. 12, 1-50.
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dynamics in Lake Ontario before and after the establishment of Dreissena spp., Cercopctgis pengoi,
and Bythotrephes longimamis. Can. J. Fish. Aquat. Sci. 68, 795-811.
Jude, D.J., Rudstam, L.G., Holda, T.J., Watkins, J.M., Euclide, P.T., Balcer, M.D., 2018. Trends in Mysis
diluvictnct abundance in the Great Lakes, 2006-2016. J. Great Lakes Res. 44, 590-599.
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storm: Disappearing winter bloom in Lake Michigan. J. Great Lakes Res. 36, 30-41.
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values from satellite observations of the Great Lakes. J. Great Lakes Res. 39, 138-152.
Lesht, B.M., Barbiero, R.P., Warren, G.J., 2016. Verification of a simple band ratio algorithm for retrieving
Great Lakes open water surface chlorophyll concentrations from satellite observations. J. Great Lakes
Res. 42, 448-454.
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and the statistical basis of estimations by counting. Hydrobiologia 11, 143-170.
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Keats, R, Rudstam, L., Hebert, P., 2001. Distribution, fecundity, and genetics of Cercopctgis pengoi
(Ostroumov) (Crustacea, Cladocera) in Lake Ontario. J. Great Lakes Res. 27, 19-32.
Pothoven, S.A., Vanderploeg, H.A., 2017.Mysis diluvictnct abundance and life history patterns following a
shift toward oligotrophy in Lake Michigan. Fund. Appl. Limnol. Arch. Hydrobiol. 190, 199-212.
Reavie, E.D., Barbiero, R.P., Allinger, L.E., Warren, G.J., 2014. Phytoplankton trends in the Great Lakes,
2001-2011. J. Great Lakes Res. 40, 618-639.
Reavie, E.D., Cai, M., Twiss, M.R., Carrick, H.J., Davis, T.W., Johengen, T.H., Gossiaux, D., Smith, D.E.,
Palladino, D., Burtner, A., 2016. Winter-spring diatom production in Lake Erie is an important driver
of summer hypoxia. J. Great Lakes Res. 42, 608-618.
Reavie, E.D., Sgro, G.V., Estepp, L.R., Bramburger, A.J., Shaw Chraibi, V.L., Pillsbury, R.W., Cai, M., Stow,
C.A., Dove, A., 2017. Climate warming and changes in Cyclotella sensu Ictto in the Laurentian Great
Lakes. Limnol. Oceanogr. 62, 768-783.
Rivier, I.K., 1998. The predatory Cladocera (Onychopoda: Podonidae, Polyphemidae, Cercopagidae) and
Leptodorida of the World. Backhuys Publishing, Leiden.
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Rudstam, L.G., Holeck, K.T., Bowen, K.L., Watkins, J.M., Weidel, B.C., Luckey, F.J., 2015. Lake Ontario
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B.C., Barbiero, R., Luckey, F.J., 2017. Nutrients, phytoplankton, zooplankton, and macrobenthos, in:
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Bowen, K.L., 2008. Hydroacoustic measures ofMysis relicta abundance and distribution in Lake
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Walsh, M.G., Lantry, B.F., Boscarino, B., Bowen, K., Gerlofsma, J., Schaner, T., Back, R, Questel, J.,
Smythe, A.G., Cap, R., 2010. Early observations on an emerging Great Lakes invader Hemimysis
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APPENDIX A - LIST OF THE SAMPLING AND ANALYTICAL
STANDARD OPERATING PROCEDURES SUPPORTING THE
GLBMP COMPONENTS
Table 1 below provides a list of the most current version of the sampling and analytical standard
operating procedures (SOPs) supporting the GLBMP variables highlighted in this report.
Table 1. Sampling and Analytical Standard Operating Procedures Supporting the GLBMP
GLNPO
Method
Title of the Standard Operating Procedure
Version Number,
Date
LG400
Standard Operating Procedure for Phytoplankton Sample
Collection and Preservation Field Procedures
Revision 09, March
2002
LG401
Standard Operating Procedure for Phytoplankton Analysis
Revision 05,
February 2010
LG402
Standard Operating Procedure for Zooplankton Sample Collection
and Preservation and Secchi Depth Measurement Field Procedures
Revision 12,
February 2017
LG403
Standard Operating Procedure for Zooplankton Analysis
Revision 08,
February 2017
LG406
Standard Operating Procedure for Benthic Invertebrate Field
Sampling Procedure
Revision 12, March
2018
LG407
Standard Operating Procedure for Benthic Invertebrate Laboratory
Analysis
Revision 09, April
2015
LG408
Standard Operating Procedure for Mysid Analysis
Revision 02,
February 2017
LG409
Standard Operating Procedure for My sis Sample Collection and
Preservation
Revision 02, April
2019
JULY 2019
PAGE | A-l
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