2012 Eastern Finger Lakes
Benthic Aquatic Invertebrate Assessment
Sample Dates: July-Sept, 2012
Report Date: February 2014
Prepared for
Cayuga County Planning Department
Prepared by
Watershed Assessment Associates, LLC
1861 Chrisler Avenue, Suite 1
Schenectady, NY 12303
FOREWORD
Bruce R. Natale, P.E.
Cayuga County Planning Department
Cayuga County sponsored this fieldwork and study as part of their joint Southern Lake Ontario – Finger
Lakes Region Aquatic Invertebrate Monitoring and Prevention Program with the Finger Lakes Institute,
which was funded under an United States Fish and Wildlife Service Great Lakes Restoration Initiative
Grant. The purposes of this study included assessing the health of the macroinvertebrate communities
of the Eastern Finger Lakes, while also identifying any new aquatic invasive species of concern. Two
such invasive species were found only in Seneca Lake during this study: bloody red shrimp (Hemimysis
anomala) and faucet snail (Bithynia tentaculata). Since these two occur in only one of the seven lakes,
perhaps our collective efforts to limit lake to lake spread of aquatic invasive species in 2014 should
specifically include these two species. This is especially true for the faucet snail because it is an
intermediate host to a trematode that is deadly to waterfowl and other water birds that feed on snails,
and has been documented as the cause of major waterfowl die-offs in Wisconsin.
Two other aquatic invasive species of interest were found; Echinogammarus ischnus and
Cipangopaludina sp. This study appears to be the first documented occurrence of E. ischnus in the
Finger Lakes and it was found in all seven. Immature specimens of the Chinese mystery snail
(Cipangopaludina sp) were found in Keuka and Canandaigua Lakes. This species is also known to
occur in the Owasco Lake Outlet.
One surprise was the relatively low numbers of aquatic invasive macroinvertebrates found. This is
especially true for Cayuga and Owasco Lakes, where only three were sampled in each. This may be due
to the large winter drawdowns in these two lakes, because the standard BMI sampling protocol actually
surveyed lake bed which was dry/exposed just four to six months earlier. The impact of large winter
drawdowns on macroinvertebrates in the Finger Lakes may be a topic for further study.
Partial funding for this program is supported by a grant/cooperative agreement from the
U.S. Department of the Interior, Fish and Wildlife Service.
2
Background
The Finger Lakes comprise eleven freshwater
lakes in western New York State. The lakes are
a significant ecological, economic and
recreational asset to the region. All but one of
the Finger Lakes are used for public water
supply, and the entire region is a popular tourist
destination. Given the importance of the Finger
Lakes to the region’s communities, ecology and
economy,
understanding
the
ecological
condition or “health” of these lakes is central to
effective long-term management of this
resource. Watershed Assessment Associates,
LLC (WAA) was contracted by the Cayuga
County Planning Department in 2012 to perform
an assessment of benthic invertebrate
communities in the seven eastern Finger Lakes:
Canandaigua, Cayuga, Keuka, Otisco, Owasco,
Seneca, and Skaneateles.
Benthic macroinvertebrates are widely regarded
as effective indicators of environmental
conditions in aquatic systems, and are routinely
used by natural resource management agencies
to assess and monitor ecosystem condition.
Benthic macroinvertebrates are an important
component in the aquatic food web, serving as
an intermediate link between primary producers
(such as algae) and predators such as fish and
amphibians. Macroinvertebrate communities
are diverse, and sensitivity to water pollution
and habitat degradation varies among groups
and species. This diversity, coupled with
variable tolerance to disturbance, renders
benthic macroinvertebrates a particularly useful
group of organisms for assessing ecosystem
health.
In addition to the many native species that serve
as effective indicators of environmental
conditions, non-native macroinvertebrates have
been accidentally introduced into the Finger
Lakes by boaters and other lake users. These
invasive aquatic species include plants and
animals that lack natural predators within the
ecosystem, and therefore reproduce and spread
rapidly. Significant ecological consequences can
ensue, including changes to water quality and to
the abundance of native species, including game
fish. Significant efforts are underway in the
Finger Lakes region to inform boaters and other
lake users about invasive species, their potential
consequences, and what to do to help control
their spread.
Understanding the current
distribution and abundance of invasive species
in the Finger Lakes is critical to their long-term
management with respect to this issue.
Despite the importance of the Finger Lakes to the
region, no comprehensive assessment of
macroinvertebrate communities in the lakes has
occurred. Accordingly, the purpose of this
project was to describe the current biodiversity
of benthic aquatic invertebrate communities in
these seven lakes, including the current
distribution and abundance of aquatic invasive
benthic invertebrates within and among the
lakes. The results of this study will also serve as
a baseline of macroinvertebrate community
conditions against which future conditions in
these seven eastern Finger Lakes can be
compared.
This study follows New York State Department
of Environmental Conservation (NYS DEC) lake
assessment protocols, which are also consistent
with US EPA methodology (USEPA 2009). The
assessment is timely in that there are currently
federal and state efforts underway throughout
the country to assess the water quality of lakes.
In 2009, the EPA led a nationwide assessment of
lakes that included characterizing biological
conditions (USEPA 2009). As a collaborator in
the National Lakes Assessment, the NYS DEC
initiated benthic community sampling in 2007 in
order to develop a standardized lake biological
assessment tool for the state of New York. Once
completed, the lake biological assessment tool
will enable characterization of ecological
condition and impairment (including degree of
impact and potential impact sources). In the
interim, this study utilizes the assessment tool
while it is still under development. As such, it is
premature to ascribe or assign condition
classifications to the lakes based on the results of
this study. Rather, the results of this study are
used to describe and compare conditions across
the seven lakes included in the project.
Additional sampling was performed in Owasco
Lake to assess deep-water benthic community
conditions in the lake. Sampling was performed
using a Ponar grab sampler at ten sites
previously assessed in 2006 (Watkins et al. 2007).
The Ponar sampling results are presented
discussed and compared in a separate report
titled “Owasco Lake, Cayuga County, NY, 2012
Deep Water Macroinvertebrate Community
Assessment.”
Methods
Site Selection and Field Methods
Sampling in Canandaigua, Keuka, and Otisco
lakes was limited to eight sites distributed
throughout each lake and was intended to
capture benthic community conditions from
each of the dominant substrate types
represented in each lake. Duplicate samples
were collected from each of these eight locations;
the first sample was combined among sites to
produce a single eight-site composite, while the
second sample from each site was preserved
separately. This effort resulted in a total of eight
site-specific samples and a single eight-site
composite sample from each of these three lakes
(Table 1).
Field sampling of aquatic invertebrate
communities was performed by WAA in the
summer of 2012 following New York State
Department of Environmental Conservation
(NYS DEC) protocols and using a sampling
design developed with assistance from the NYS
DEC. Assessments of Cayuga, Owasco, Seneca,
and Skaneateles lakes included sampling from
16 sites. Eight sites were selected at the north
end of each lake to assess community conditions
in close proximity to heavy-use areas such as
major boat launches and marinas; an additional
8 sites were selected throughout each lake to
represent cobble, eroded shale, silt, and
clay/muck substrate types.
Each site was
sampled using NYS DEC methods for sampling
from littoral-zone lake environments. Duplicate
samples were collected at the eight north-end
sites; the first sample was combined among the
sites to produce a single eight-site composite,
while the second sample was preserved
separately from each site to assess site-specific
conditions
and
variability
among
sites/substrates. A single sample was collected
from each of the eight sites distributed across the
entire length of each lake (an additional two sites
were sampled in Cayuga Lake to provide
adequate spatial coverage of the lake margin);
these samples were not composited. This
sampling effort resulted in a total of sixteen sitespecific samples and a single eight-site
composite sample from each of these four lakes
(Table 1).
Sorting and Organism Identification
Laboratory processing of all samples was
performed by WAA following NYS DEC
laboratory protocols for processing freshwater
benthic macroinvertebrate samples (Alexander
J. Smith, NYS DEC, personal communication).
All littoral-zone samples (both composites and
site-specific) were processed to remove a 300organism (± 10%) subsample, while the ten
Owasco Lake deep-water samples were
processed to remove a 100-organism subsample
from randomly selected portions of the sample
substrate.
All
macroinvertebrates
were
identified to the lowest practical taxonomic level
(generally genus or species) as allowed by
existing keys. Taxonomic identification was
performed by WAA taxonomists certified by the
Society for Freshwater Science.
4
Following removal of the 300-organism
subsample, the remaining unsorted sample
fraction was visually inspected for any larger
organisms that may not have been encountered
during the subsampling procedure (referred to
as a “large and rare scan”). These “large/rare”
specimens were placed in a separate vial and
identified separately from the organisms in the
subsample.
NYS DEC has only recently
performed large/rare scans in their own
macroinvertebrate
sample
processing
procedures and does not currently include the
large/rare specimens in their data analyses.
Accordingly, the large/rare data produced in
this study were used only to further ascertain the
presence of invasive organisms that were not
encountered during subsampling. However, all
large/rare specimens identified for this project
are included in the raw taxonomic data and
flagged as large/rare specimens.
developed. In the future, such scoring criteria
and condition classes will be available for NYS
lakes, but until then, the use of these community
metrics is restricted to making comparisons of
relative condition within waterbodies over time
or among waterbodies, based on differences in
raw metric scores. Additionally, this metric set
was selected by the NYS DEC for use on data
from lakes smaller and more shallow than the
Finger Lakes (Alexander J. Smith, NYS DEC,
personal communication), which may limit their
utility in Finger Lake analysis. Therefore,
several additional metrics were used in this
assessment as included below (Table 2).
Results and Discussion
Environmental Characterization
Land use, as determined from observations
made from lake-wide sampling stations, varied
both within and among the lakes (Table 3).
Moderate to extensive residential development
was present at most sampling stations in
Canandaigua, Cayuga, Owasco, and Skaneateles
lakes (Table 3). Moderate to extensive
development was less frequent on Keuka,
Otisco, and Seneca lakes.
Lake-front
development has the potential to threaten lake
health through increases in stormwater runoff
that may contain nutrients, bacteria, organic
material, and other pollutants.
Macroinvertebrate Community Metrics
Raw macroinvertebrate taxonomic and count
data were summarized using twelve community
metrics recommended for lake samples collected
in New York State and used by NYS DEC in its
Lake Biomonitoring Pilot Project (Alexander J.
Smith, personal communication; Table 2).
Biological assessment of a waterbody ultimately
aims to determine the current status of the
biological community relative to its potential
state. Generally, numeric scores are converted to
standard condition classes (excellent, good, fair,
poor) that qualitatively describe the degree of
divergence between measured and desired
states.
Increasing divergence between the
observed and potential states results in
decreasing condition.
Because biological
assessment tools for NYS lakes are still in
development, criteria that allow the conversion
of community raw metric values to standardized
scores and assignment of waterbodies to
biological condition classes have not yet been
Littoral zone substrate conditions were similar
among the lakes, as cobble or gravel was the
dominant substrate in at least half of the littoral
zone stations in each lake (Table 4). Sand was
the sub-dominant substrate in at least half of the
sample stations in each lake.
Littoral zone cover types were also similar
among lakes, as the most common dominant
cover type was cobble or gravel in each lake.
Furthermore,
benthic
algae
were
the
5
subdominant cover type at most stations on each
lake (Table 5).
from which to calculate richness, resulting in the
lower total taxa richness.
Water chemistry measured during collection of
macroinvertebrate samples suggests generally
similar water quality among the seven lakes
(Table 6). As only grab samples were collected
during macroinvertebrate sampling, the water
chemistry data are limited in their utility in
describing specific water quality issues or
potential
effects
on
macroinvertebrate
communities.
While an analysis of water
chemistry is beyond the scope of this study, the
data collected provide some additional
immediate environmental context under which
macroinvertebrate sampling was performed.
Photo 1. Stenonema femoratum, a mayfly in the family
Heptageniidae. Members of this family are often found
in streams.
The average taxa richness from individual lakewide samples was uniformly lower than was
taxa richness derived from the composite
samples. Taxa richness averaged 23.1 from
individual whole-lake samples (versus 37.7 from
composite samples), illustrating the value of
collecting from a variety of habitats and
locations within a waterbody (Figure 1).
Importantly, in this case (individual lake-wide
samples versus composite samples) subsample
sizes (number of organisms identified per
sample) were similar for each sample type.
Considering these overall taxa richness results,
Seneca Lake currently supports the lowest
biodiversity among the seven sampled lakes
(Figure 1). Taxa richness, as determined both
from composite samples and individual lakewide sample means was highest in Owasco
Lake, followed by Keuka Lake and Skaneateles
Lake (Figure 1). Total richness from Otisco
Lake’s composite sample was higher than from
Canandaigua Lake and Cayuga Lake, yet
composite sample results suggested a
potentially higher richness in the latter two lakes
than in Otisco.
Macroinvertebrate Communities
Taxa Richness and Community Diversity
A total of 206 unique macroinvertebrate taxa
were identified from the seven Finger Lakes
included in this study. Total taxa richness varied
both among lakes and among sample types
within lakes. Pooled data from the lake-wide
site specific samples consistently yielded the
highest taxa richness estimates. Taxa richness
from pooled lake-wide sample data was
approximately twice as high as richness
estimates derived from the composite sample
data, averaging 73 taxa per lake and ranging
from 45 taxa in Seneca Lake to 87 taxa in Keuka
Lake. Composite samples yielded the lowest
estimates of taxa richness in each lake, averaging
37.7 taxa and ranging from 31 taxa in Seneca
Lake to 46 taxa in Keuka Lake. The significant
difference in the number of taxa from pooled
lake-wide sample data and a single composite
sample is due to the larger sample sizes in the
pooled data. The eight lake-wide samples
processed separately resulted in an average of
2,400 individuals per lake from which to
calculate taxa richness estimates. By contrast,
the composite samples averaged 300 organisms
6
Furthermore, the one mayfly taxa sampled from
Seneca Lake, Callibaetis sp., is one of the most
tolerant of water pollution among the mayflies
found in the Finger Lakes.
Absent from the Seneca Lake samples, but
occurring in the six other lakes were at least two
of the three Heptageniidae taxa, Stenacron
interpunctatum, Stenonema femoratum, and
Leucrocuta sp., which are predominantly lotic but
can be found in well-oxygenated waters of rocky
shorelines that receive abundant wave action.
Photo 2. The mayfly Caenis sp. is common in lakes
and ponds. With sufficient available food resources,
densities can exceed 1000 individuals per square
meter.
Four lakes, including Canandaigua, Keuka,
Owasco and Skaneateles, supported the
burrowing
mayfly
Ephemera
simulans
(Ephemeridae). This taxon was most abundant
in Skaneateles Lake. Hexagania limbata, another
member of this mayfly family, was present in
very low abundance in Skaneateles and Owasco
lakes. Members of this family are sensitive to
water quality impairment; their presence is
therefore considered an indicator of good water
quality in lentic systems.
The Shannon Diversity Index is currently
included in the NYS lakes metric list. This index
assesses both the number of species (richness)
and the proportional abundance of each
(evenness) to quantify diversity. On a scale of 0
(least diverse) to 5 (most diverse), Shannon
diversity scores from lake-wide samples ranged
from a low of 0.9 in Seneca Lake to a high of 2.0
in both Owasco and Skaneateles lakes (Table 7
and Figure 2). The overall mean Shannon Index
score across all seven lakes was 1.7 (as
determined from lake-wide samples) and scores
from six of seven lakes ranged from 1.6 to 2.0,
indicating similar diversity among most of the
lakes.
Similarly, caddisfly richness ranged from two
taxa in Seneca Lake to nine taxa in Skaneateles
and Keuka lakes, and ranged between four and
six taxa among the other four lakes (Figure 3).
These results clearly suggest that Seneca Lake is
currently less suitable for supporting diverse
mayfly and caddisfly communities than are the
other lakes included in this study.
In addition to the core NYS DEC lake metrics
currently in use (Table 2), mayfly and caddisfly
richness were each calculated for each lake by
sample type. Because mayflies and caddisflies
are considered the most sensitive among the
major macroinvertebrate taxonomic groups
found in the Finger Lakes, variation in richness
among these groups could provide important
insights into difference in the ecological
condition among the lakes. Mayfly richness, as
determined from pooled lake-wide data, ranged
from a low of one taxon in Seneca Lake to a high
of nine taxa in Skaneateles Lake (Figure 3).
Mayfly richness ranged from five to eight among
the other five lakes.
Among the seven lakes were 4 species of Oecetis
sp. (Trichoptera: Leptoceridae), as this is a
typical lentic taxon. Agarodes sp. (Trichoptera:
Sericostomatidae), a widespread burrowing
caddisfly that occurs in both lotic and lentic
habitats, was present in Skaneateles Lake. Other
sampled taxa that are common to lotic habitats
but also occur in rocky wave-action lentic
shorelines included the caddisflies Helicopsyche
borealis (Trichoptera: Helicopsychidae) and
Pycnopsyche sp. (Trichoptera: Limnephilidae).
7
Community Evenness/Dominance
while Pelecypeda (freshwater clams) both native
and invasive were secondarily dominant in
Canandaigua and Otisco lakes (Figure 4).
All sample types (north-end, lake-wide, and
composites) indicated that macroinvertebrate
communities were dominated by non-insects in
six of the seven lakes (Figure 1). Only
Skaneateles Lake was numerically dominated by
insects (Figure 1: % non-insects and ETO
individual graphs), and only by whole-lake
sample results. Organisms representing the
orders
mayfly,
caddisfly,
and
dragonfly/damselfly (ETO individuals) were
relatively abundant only in Skaneateles Lake
(Figure 1: ETO individuals’ graph). This high
ETO abundance was driven primarily by the
abundance of the mayfly genus, Caenis sp. In
fact, Caenis sp. was the most abundant taxon in
Skaneateles Lake, representing nearly one-third
of all individuals collected from this lake. In
contrast, the freshwater crustacean, Gammarus
sp., was the most abundant taxon collected at all
six other lakes (Figure 4: see Amphipod
abundance in charts).
Numeric dominance by a single taxon provides
some insight into the ecological health of a
waterbody; waters heavily dominated by a
single taxon are said to be “out of balance”
whereby conditions are not representative of
longer-term norms and are more favorable for
one or a few taxa than for the larger community
as a whole. Circumstances leading to this
condition may include increased nutrient
concentrations, changes in the temperature
regime of the system, or other environmental
changes favorable to only certain species.
Across six of the seven Finger Lakes studied,
dominance by a single taxon was similar,
ranging from 42.8% to 55.4% from lake-wide
samples (Table 7 and Figure 1: Dominant Taxon
graph). However, dominance by a single taxon
(Gammarus) was 79.1% in Seneca Lake;
conspicuously higher than in the other lakes.
Further investigation of what environmental or
ecological conditions in Seneca Lake may be
enhancing Gammarus populations should be
considered.
Crustacean and Mollusk Richness
Freshwater crustaceans and mollusks were
represented by an average of at least five taxa in
lake-wide samples across all seven Finger Lakes,
ranging from 5.4 taxa in Otisco Lake to 9.8 taxa
in Owasco Lake (Table 7 and Figure 2). These
totals include both native and invasive taxa.
Twenty-five native and non-native mollusk taxa
were sampled from across the seven Finger
Lakes. Freshwater snail diversity was high
among the seven lakes, represented by 15
unique genera and 19 unique species therein.
One of these taxa, the Chinese mystery snail
(Cipangopaludina sp.) is an invasive species and
was sampled from Keuka and Canandaigua
lakes.
Photo 3. Cipangopaludina is a snail native to Asia. Its
maximum size is greater than any snail native to the
Northeast.
As the relative abundance of major taxonomic
groups varied among lakes, four major
taxonomic groups were generally dominant
throughout the seven lakes: Amphipoda,
Diptera, Gastropoda, and Pelecypoda (Figure 4).
While Amphipoda were dominant in six of
seven lakes, Diptera (true flies) were secondarily
dominant in Cayuga, Keuka, and Owasco lakes,
8
without knowledge of conditions in leastdisturbed lake environments, the extent to
which these scores indicate impairment to
macroinvertebrate communities in the Finger
Lakes is indeterminable. Importantly, HBI
scores show a relatively narrow range of values
across these seven lakes, indicating generally
similar conditions with respect to community
tolerance to organic enrichment pollution.
Photo 4. The invasive Echinogammarus ischnus was
found in all seven Finger Lakes included in this study.
It is native to the Ponto-Caspian region of Asia. Part
of a group of amphipods commonly called “scuds”; it
spends much of its time in the bottom sediments
Percent tolerant individuals also showed a
narrow range of values across six of the seven
Finger Lakes, ranging from 28.8% to 32.4%
(Table 7 and Figure 2). Seneca Lake’s percent
tolerant individuals’ value (14.6%) was roughly
half that of the mean values across all lakes, and
resulted primarily from Gammarus sp. not being
classified as a tolerant taxon.
Among the five Pelecypoda (“bivalve”) mollusk
taxa sampled during this study, three are
invasive species, including the zebra mussel
(Dreissena
polymorpha),
quagga
mussel,
(Dreissena bugensis), and Asian clam (Corbicula
fluminea). The occurrence of these and other
invasive invertebrate species in the Finger Lakes
will be discussed in detail later in this report.
Feeding Group Composition
The relative abundance of organisms with
different feeding strategies (feeding groups) can
provide insight into what are the dominant
sources of energy available to macroinvertebrate
communities. For example, a high abundance of
organisms that filter-feed suspended organic
materials from the water column may indicate a
high abundance of phytoplankton resulting
from excessive nutrients. Moreover, among the
functional feeding groups, filter-feeders are
generally regarded as the most tolerant to water
pollution, while organisms that breakdown
coarse organic material with their mouthparts
(shredders) are regarded as a relatively sensitive
functional group.
Community Tolerance
Community conditions in relation to collective
tolerance to water pollution were expressed
using two metrics: the Hilsenhoff biotic index
(HBI) and percent tolerant individuals, both of
which are included on the provisional NYS DEC
lakes metric list. HBI score ranges from 0 to 10
and indicates overall community tolerance to
organic enrichment pollution. The percent
tolerant individuals’ metric indicates the percent
of individuals within the sample that are
considered generally tolerant to water pollution:
higher proportions of tolerant individuals
indicate water quality perturbations that have
adversely impacted the macroinvertebrate
community.
As would be expected in lake samples,
shredders represented a small fraction of the
macroinvertebrate community, averaging 1.0%
of the total community composition in lake-wide
samples across all lakes. Percent shredders were
uniformly low across all lakes, ranging from
0.1% in Seneca Lake to 3.4% in Otisco Lake
(Table 7 and Figure 2).
HBI scores from lake-wide samples averaged 6.4
across all lakes, and ranged from 6.1 in
Skaneateles Lake to 6.7 in Otisco Lake (Table 7
and Figure 2). While these scores range in the
upper half of the possible range of scores,
9
Owasco Lake; further research and inquiry is
necessary to determine whether this study
represents the first reports of this snail in
Canandaigua and Keuka lakes.
Filtering organisms were more abundant in all
lakes than were shredders, averaging 12.6% of
the total community across all lakes in lake-wide
samples. Some variation in this metric occurred,
as values ranged from 7.2% in Seneca Lake to
17.6% in Owasco Lake.
Photo 6. The bloody-red shrimp, Hemimysis anomala,
is native to the Ponto-Caspian region of Asia. During
daylight hours, large numbers of individuals can
aggregate in swarms which are often observed in the
shadows of docks, etc.
Photo 5. The Longhorn Caddisfly (family
Leptoceridae) Oecetis is a predator. It’s often found
foraging amongst rocks and root mats, but some
species are capable swimmers.
The invasive Amphipod Echinogammarus ischnus
(Amphipoda: Gammaridae) was found in all
seven Finger Lakes included in this study (Table
8). Lake-wide and north-end replicate sampling
resulted in detections across all lakes, while
composite sampling resulted in detections only
in Canandaigua and Keuka lakes. To our
knowledge, this study represents the first
documented occurrence of E. ischnus in the
Finger Lakes. Native to the Caspian Black-Sea
region, E. ischnus was first reported in North
America from the Detroit River in 1994 (Wit et
al. 1997). This invasive amphipod has since been
reported from all of the Great Lakes, as well as
from the St. Lawrence, St. Clair, and Niagara
rivers (Dermott et al. 1998; Palmer and Ricciardi
2004). Documented ecological impacts include
the displacement of the native amphipod
Gammarus fasciatus from many areas in the Great
Lakes (Dermott et al. 1998; Stewart et al. 1998a,
1998b; Nalepa et al. 2001; Ratti and Barton 2003;
van Overdijk et al. 2003; Haynes et al. 2005).
Some evidence suggests that E. ischnus,
potentially by way of co-evolving with
dreissenid mussels, is offered a competitive
Invasive Species
Seven invasive benthic aquatic invertebrate
species were sampled during this study,
including three Pelecypoda (clams), two
Gastropoda (snails), one Mysida (mysid
shrimp), and one Amphipoda (Table 8). Zebra
mussels (Dreissena polymorpha), previously
documented from all seven Finger Lakes, were
sampled from all seven lakes in this study (Table
8). Quagga mussels (D. bugensis), previously
documented from five of the seven lakes (not
presently known from Otisco or Owasco lakes),
again occurred in five of the seven composite
samples.
The Asian clam (Corbicula fluminea) was found in
Owasco, Otisco, and Keuka lakes, where it has
been previously documented.
Immature
specimens
of
Chinese
mystery
snails
(Cipangopaludina sp.) were found in both Keuka
and Canandaigua lakes (Table 8). The Chinese
mystery snail was only recently confirmed in
10
zooplankton, altered levels of primary
production, and impacts to fish communities
(Brown et al. 2012).
advantage over G. fasciatus in environments
where dreissenids are abundant (van Overdijk et
al. 2003, Ricciardi & MacIsaac 2000). As such,
expansion of the quagga (D. bugensis) and zebra
(D. polymorpha) mussels throughout the Finger
Lakes may have conferred a competitive
advantage to E. ischnus over G. fasciatus. As E.
ischnus has likely only been recently introduced
into the Finger Lakes region, an opportunity
presently exists to document ongoing ecological
impacts in relation to potential increases in
abundance throughout the Finger Lakes.
The largest number of invasive species was
collected from Seneca and Keuka lakes, with five
taxa collected from each. Seneca Lake supported
two species not sampled from any other lakes in
this study: Hemimysis anomala and Bithynia
tentaculata. Previously documented in Seneca
Lake (Brown et al. 2012), the mysid shrimp,
known by its common name as the bloody red
shrimp (Hemimysis anomala), was detected in
Seneca Lake in the present study in both lakewide and north-end samples. Thought to be
introduced into the Great Lakes via ballast water
exchange, this European species was first
reported from the Great Lakes in 2006. 2010
surveys found H. anomala distributed
throughout Seneca Lake’s 61-km length, yet did
not detect the species in any of the other ten
Finger Lakes (Brown et al. 2006). As such, “jump
dispersal” (successful dispersal over a long
distance, for example from one waterbody to the
next by boat) to Seneca Lake from the Great
Lakes is suspected (Brown et al. 2006).
Photo 7. The faucet snail, Bithynia tentaculata, is
native to Europe and western Asia. It’s a small
species, inhabiting lakes, ponds and low-velocity
rivers.
Like H. anomala, Bithynia tentaculata is native to
Europe. Commonly known as the faucet snail,
this species was first introduced into the Great
Lakes in the 1870s and has since spread through
several river systems
throughout the
northeastern and central United States. The
faucet snail is an intermediate host to a
trematode that is deadly to waterfowl and other
water birds that feed on snails. Major waterfowl
die-offs have been documented in Wisconsin
following ingestion of infected faucet snails.
Furthermore, faucet snails have been
documented displacing native snails following
their introduction (Jokinen 1992). Between 1917
and 1968, a 15% decline in mollusk biodiversity
was documented in New York’s Oneida Lake
(immediately northeast of the Finger Lakes, and
considered by some to be the “thumb” of the
Finger Lakes) while faucet snails increased in
abundance (Harman 2000).
Previously
documented in Seneca Lake, the only waterbody
in the present study from which this species was
collected, the authors of this report are not aware
of its occurrence in other Finger Lakes.
The species has also been found in the SenecaCayuga Canal, raising concerns that H. anomala
may eventually spread throughout the New
York Canal system via the Erie Canal and its
tributaries (Brown et al. 2012). While the
ecological impacts to Seneca Lake are as of yet
unknown, its impact to European lakes upon
introduction has been documented and includes
declines in abundance and diversity of
11
While the largest number of invasive species
was sampled from Seneca Lake (along with
Keuka Lake), neither the Asian clam nor the
Chinese mystery snail were sampled from this
lake. The Asian clam has been previously
documented from Seneca Lake, and it’s likely
still present, further indicating that even a study
of this size may not detect all invasive species in
all waterbodies.
suggest that neither the composite nor replicate
sampling efforts extended in this study were
adequate to detect all invasive species in all
lakes. As such, even this study may not provide
complete documentation of the occurrence of all
invasive macroinvertebrates in these seven
Finger Lakes. It should also be noted that no
large/rare searches added to any invasive taxa
lists for any of the lakes.
North-End versus Lake-Wide Results
Generally, results of sampling from the north
end of Cayuga, Owasco, Seneca, and Skaneateles
lakes yielded results that were similar to those
obtained from lake-wide sampling (see Figures
1 and 2). Two-sample t-tests were performed on
the three metrics (total richness, percent
dominant, and Shannon diversity index) that
were deemed to potentially provide the best
discriminatory ability based on variability
among replicates and sensitivity to disturbance.
No significant differences in any metrics
occurred between lake-wide and north-end
samples in Cayuga, Owasco, and Seneca lakes.
In Skaneateles Lake, total richness was
significantly lower among the north-end
samples than it was among the lake-wide
samples (p = 0.036), yet no differences occurred
between the other two metrics. These results
generally suggest that the north ends of these
four lakes support benthic macroinvertebrate
communities that are similar in composition to
those distributed lake-wide. Accordingly, nearterm future sampling need not include northend-only sample collection.
Photo 7. Corbicula fluminea, the Asian clam, is a very
successful invasive. Individuals are hermaphroditic
and capable of self-fertilization, producing up to
100,000 offspring per year.
Replicate sampling generally produced more
robust accounts of the presence of invasive
species than did composite sampling (Figure 5).
One or two more invasive species occurred in
lake-wide replicate samples than in composite
samples in four of the seven lakes, and resulted
in four more taxa in Seneca Lake (Figure 5).
Interestingly, composite sampling resulted in
the detection of three invasives not detected by
replicate sampling: Asian mystery snails in
Canandaigua and Keuka lakes and Asian clams
in Owasco Lake. In some lakes such as
Canandaigua, the different sampling methods
produced the same number of invasive taxa, but
did not detect the same taxa. In Canandaigua,
for example, while replicate sampling failed to
detect Asian mystery snails, composite sampling
failed to detect zebra mussels. These results
Potential Effect of Drawdowns
Water levels in the Finger Lakes are typically
brought down in the late fall/early winter
(“winter drawdown”) to accommodate spring
precipitation and snowmelt. Such manipulation
of water levels has been shown to affect
macroinvertebrate community composition
12
within the drawdown zone in other waterbodies
in the northern United States (e.g., McEwen and
Butler 2010, White et al. 2007) The magnitude,
duration, and frequency of such drawdowns
will affect the size of the impact.
design elements (seasonal sampling and
sampling within and below the draw-down
level) if better understanding the effects of these
draw-downs is desired.
Conclusions
Lake elevation data for winter 2011-2012 and
again for the period during which
macroinvertebrates were sampled indicate that
the area sampled in most lakes would have been
unaffected by the winter draw-down (Table 9).
However, 2011-2012 winter draw-down in
Cayuga Lake resulted in a water level of 379 ft,
while benthic sampling occurred between 379.24
and 381.0 ft, suggesting that sampling occurred
entirely within the de-watered zone. Water level
results in Table 9 also suggest that benthic
sampling occurred partially within the dewatered zone in Owasco Lake.
Collectively, the results of this study suggest
that macroinvertebrate community composition
and structure show some variation among the
seven eastern Finger Lakes, but conditions with
respect to diversity, richness, and tolerance to
water pollution are generally similar across most
lakes. While numerous community attributes
were examined, those metrics that exhibited the
widest variability among lakes consistently
indicated relatively degraded conditions in
Seneca Lake. Examples of such metrics include
total taxa richness, mayfly richness, caddisfly
richness, ETO abundance, percent dominance by
one taxon, percent non insects, and Shannon
Diversity Index.
Samples from Seneca Lake supported the largest
number of invasive species among the seven
lakes (along with Keuka Lake). As the only
Finger Lake in which Hemimysis anomala is
currently known to occur, the contribution of
this invasive species to Seneca Lake’s current
ecological condition is presently unknown, but
the collective impacts of the numerous invasives
in this lake are likely manifested in the degraded
conditions measured in this lake relative to the
others. Continued surveys for the expansion of
this and other invasive species into and among
the Finger Lakes are highly recommended to
document such invasions and concomitant
impacts to the ecology of the lakes.
Photo 8. Northern Caddisflies (family Limnephilidae)
are common in both flowing and still waters. The
genus Pycnopsyche has representatives that inhabit
each.
While draw-downs have been documented to
affect benthic communities in other lakes, the
effects of these drawdowns on the benthic
macroinvertebrate fauna of these Finger Lakes is
currently unknown, and assessing these effects
is beyond the scope of the present study. Future
monitoring of the benthic communities in the
Finger Lakes could include additional sampling
13
Recommendations:
•
Work with NYS DEC and others to inform the public in the prevention of the spread of
Hemimysis and faucet snails from Seneca Lake, including methods for drying and
disinfection of potentially infected materials.
•
Continue monitoring with focus on replicate sampling at the same level of lake-wide
sampling effort included in this study. Sampling at least every two to three years is
recommended to allow observation of trends that may occur in relation to
introductions/expansions of invasive species.
•
Design and implement a study to assess the effect of winter drawdowns on
macroinvertebrate community composition within littoral zones to aid in interpretation
of future macroinvertebrate assessment data under variable drawdown scenarios.
•
Work in collaboration with NYS DEC in the development of a multimetric index biological
assessment tool to allow assignment of condition classes to the Finger Lakes.
•
Further investigate the relatively large deviation of Seneca Lake’s macroinvertebrate
community condition from that of the other six lakes included in the study. This would
require further examination and quantification of environmental variables potentially
affecting the benthic communities, including water quality, ecological interactions, and
physical conditions. Also examine why Gammarus are particularly abundant in this
system.
14
References
Brown, M.E., R. Morse, and K. O'Neill. 2012. Spatial, seasonal, and diel distribution patterns of
Hemimysis anomala in New York State's Finger Lakes, Journal of Great Lakes Research, Volume 38,
Supplement 2, Pages 19-24
Dermott, R., J. Witt, Y.M. Young, and M. Gonzalez. 1998. Distribution of the Ponto-Caspian amphipod
Echinogammarus ischnus in the Great Lakes and replacement of native Gammarus fasciatus. Journal of Great
Lakes Research 24(2): 442-452.
Gonzalez, M. J. and G. A. Burkart. 2004. Effects of food type, habitat, and fish predation on the relative
abundance of two amphipod species, Gammarus fasciatus and Echinogammarus ischnus. Journal of
Great Lakes Research 30(1):100-113.
Harman, W.N. 2000. Diminishing species richness of mollusks in Oneida Lake, NY, USA. The Nautilus
114(3): 120-126.
Haynes, J.M., N.A. Tisch, C.M. Mayer, and R.S. Rhyne. 2005. Benthic macroinvertebrate communities in
southwestern Lake Ontario following invasion of Dreissena and Echinogammarus. Journal of the North
American Benthological Society 24(1): 148-167.
Jokinen, E. 1992. The Freshwater Snails (Mollusca: Gastropoda) of New York State. The University of the
State of New York, The State Education Department, The New York State Museum, Albany, New York
12230. 112 pp.
McEwen, D. C., and M. G. Butler. 2010. The effects of water-level manipulation on the benthic
invertebrates of a managed reservoir. Freshwater Biology 55: 1086-1101.
Mills, E.L., J.H. Leach, J.T. Carlton, and C.L. Secor. 1993. Exotic species in the Great Lakes: a history of
biotic crises and anthropogenic introductions. J. Great Lakes Research. 19(1):1-54.
Nalepa, T.F., D.W. Schloesser, S.A. Pothoven, D.W. Hondorp, D.L. Fanslow, M.L. Tuchman, and G.W.
Fleischer. 2001. First finding of the amphipod Echinogammarus ischnus and the mussel Dreissena
bugensis in Lake Michigan. Journal of Great Lakes Research 27(3): 384-391.
Van Overdijk, C.D.A., I.A. Grigorovich, T. Mabee, W.J. Ray, J.J.H. Ciborowski, and H.J. MacIsaac. 2003.
Microhabitat selection by the invasive amphipod Echinogammarus ischnus and native Gammarus
fasciatus in laboratory experiment and in Lake Erie. Freshwater Biology 48(4): 567-578.
Palmer, M.E., and A. Ricciardi. 2004. Physical factors affecting the relative abundance of native and
invasive amphipods in the St. Lawrence River. Canadian Journal of Zoology 82: 1886-1893.
Ratti, C., and D.R. Barton. 2003. Decline in the diversity of benthic invertebrates in the wave-zone of
eastern Lake Erie, 1974-2001. Journal of Great Lakes Research 29: 608-615.
15
Ricciardi, A., and H.J. MacIsaac. 2000. Recent mass invasion in the North American Great Lakes by PontoCaspian species. Trends in Ecology and Evolution 13(2): 62-65.
Stewart, T.W., J.G. Miner, and R.L. Lowe. 1998a. Quantifying mechanisms for zebra mussel effects on
benthic macroinvertebrates: organic matter production and shell-generated habitat. Journal of the North
American Benthological Society 17: 81-94.
Stewart, T.W., J.G. Miner, and R.L. Lowe. 1998b. Macroinvertebrate communities on hard substrates in
western Lake Erie: structuring effects of Dreissena. Journal of Great Lakes Research 24: 868-879.
USEPA. 2009. National Lakes Assessment: A Collaborative Survey of the Nation’s Lakes. EPA-841-R09-001. United State Environmental Protection Agency, Office of Water and Office of Research and
Development, Washington, D.C.
White, M. S., M. A. Xenopoulos, R. A. Metcalfe, K. Somers. 2007. The Effect of Hydroelectric Reservoir
Draw-down on Benthic Macroinvertebrate Communities of Stony Littoral Habitats: an Application of
the Reference Condition Approach. Presentation at the 55th Annual Meeting of the North American
Benthological Society, Columbia, SC.
Witt, J.D.S., P.D.N. Hebert, and W.B. Morton. 1997. Echinogammarus ischnus: another crustacean invader
in the Laurentian Great Lakes basin. Canadian Journal of Fisheries and Aquatic Sciences 54(2): 264-268.
16
Table 1. Macroinvertebrate sampling effort summary for the eastern Finger Lakes regional benthic aquatic
invertebrate assessment, summer 2012. Two additional site-specific samples were collected from Cayuga Lake
to ensure adequate spatial coverage of the lake for lake-wide sampling.
Lake
Canandaigua Lake
Keuka Lake
Seneca Lake
Cayuga Lake
Owasco Lake
Skaneateles Lake
Otisco Lake
Total
Littoral-Zone Samples
Site-Specific Composite
8
1
8
1
16
1
18*
1
16
1
16
1
8
1
90
7
17
Deep-Water Samples
Site-Specific
--------10
----10
Table 2. NYS DEC Lake Biomonitoring Pilot Project metrics utilized to characterize benthic macroinvertebrate
communities in the Eastern Finger Lakes, summer 2012.
Metric
Total Taxa
Mean Number
Individuals Per Taxon
Description
Species richness is the total number of species or taxa found in the subsample. Higher
species richness values are mostly associated with undisturbed sediment conditions (taxa
encountered only during large/rare searches were included in this count of total taxa)
Mean number of individuals per taxon in the 300-count subsample removed from the
original field samples
ETO Richness
Number of taxa represented by Ephemeroptera (mayflies), Trichoptera (caddisflies), and
Odonata (dragonflies and damselflies). These groups largely comprise taxa intolerant of
water pollution; better water quality equates with higher richness in these orders
Dominance 1
Species dominance is a measure of community balance, or how evenly the most numerous
species contribute to the community. High dominance values indicate unbalanced
communities strongly dominated by one or more numerous species
Percent Oligochaeta
Percent Non-Insects
Percent of aquatic worms in sample; generally, a higher relative abundance of worms
suggests lower water quality
Percent of non insect individuals in sample; generally, a higher relative abundance of noninsects suggests lower water quality
Number of
Crustacea/Molluska
Taxa
Number of taxa represented by freshwater Crustacea and Molluska
Shannon Diversity
A measure of biological diversity of the sampled habitat, accounting for both taxa richness
and relative abundance of each taxon. Values range from 0 to 5, with larger values equating
with higher species diversity
HBI (Hilsenhoff's Biotic
Index)
Biotic Index, or the Hilsenhoff biotic index (Hilsenhoff 1987), is calculated by multiplying the
number of individuals of each species or taxa by its assigned tolerance value, summing
these products, and dividing the total number of individuals. Tolerance values range from
intolerant (0) to tolerant (10). High biotic index values are suggestive of organically enriched
condition, while low values indicate naturally occurring, ambient communities
Percent Tolerant
Individuals
Relative abundance of organisms in the sample that are classified as tolerant to water
pollution
Percent Shredders
Relative abundance of organisms belonging to the "shredder" functional feeding group,
generally regarded as a relatively sensitive assemblage of macroinvertebrates
Percent Filterers
Relative abundance of organisms belonging to the "filterer" functional feeding group,
generally regarded as a relatively tolerant assemblage of macroinvertebrates
18
Table 3. Adjacent shoreline cover types observed during lake-wide biological assessments of the eastern Finger Lakes
performed in summer 2012.
Cover Type
Cover Class
Canandaigua
Keuka
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Waterbody
FOREST
none
rare (5%)
sparse (5-25%)
moderate (25-75%)
extensive (>75%)
0%
25%
50%
25%
0%
0%
13%
38%
38%
13%
13%
0%
13%
50%
25%
10%
30%
0%
40%
20%
0%
25%
0%
50%
25%
0%
13%
50%
25%
13%
25%
0%
0%
63%
13%
GRASS
none
rare (5%)
sparse (5-25%)
moderate (25-75%)
extensive (>75%)
0%
25%
0%
50%
25%
0%
38%
25%
13%
25%
13%
50%
25%
0%
13%
0%
40%
40%
10%
10%
0%
50%
25%
25%
0%
0%
25%
25%
50%
0%
0%
38%
38%
13%
13%
SHRUB
none
rare (5%)
sparse (5-25%)
moderate (25-75%)
0%
25%
63%
13%
0%
13%
38%
50%
13%
0%
0%
88%
10%
0%
40%
50%
0%
0%
75%
25%
0%
0%
63%
38%
13%
13%
50%
25%
BARE
none
rare (5%)
sparse (5-25%)
moderate (25-75%)
0%
0%
50%
50%
13%
25%
63%
0%
0%
63%
38%
0%
0%
40%
40%
20%
0%
13%
63%
25%
0%
38%
38%
25%
0%
38%
38%
25%
DEVELOPMENT
none
rare (5%)
sparse (5-25%)
moderate (25-75%)
extensive (>75%)
0%
0%
13%
63%
25%
13%
0%
50%
25%
13%
25%
13%
25%
25%
13%
0%
10%
10%
70%
10%
0%
13%
13%
75%
0%
13%
0%
13%
75%
0%
25%
13%
25%
25%
13%
19
Table 4. Dominant and secondary substrate observed during lake-wide biological assessments of the eastern Finger
Lakes performed in summer 2012.
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Secondary
Keuka
Dominant
Substrate
boulders
cobble or gravel
sand
silt/clay/muck
Canandaigua
Waterbody
0%
75%
25%
0%
0%
75%
13%
13%
0%
100%
0%
0%
0%
80%
10%
10%
0%
50%
50%
0%
0%
88%
13%
0%
13%
63%
0%
25%
cobble or gravel
sand
silt/clay/muck
0%
75%
25%
13%
75%
13%
0%
100%
0%
30%
50%
20%
13%
75%
13%
0%
88%
13%
25%
63%
13%
Table 5. Dominant and secondary benthic cover types observed during lake-wide biological assessments of the
eastern Finger Lakes performed in summer 2012.
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Secondary
Cover Type
boulders
cobble or gravel
sand
silt/clay/muck
Keuka
Dominant
Canandaigua
Waterbody
25%
63%
13%
0%
13%
88%
0%
0%
13%
88%
0%
0%
10%
90%
0%
0%
0%
100%
0%
0%
25%
63%
0%
13%
38%
50%
13%
0%
benthic algae
macrophytes
none
woody debris
88%
13%
0%
0%
100%
0%
0%
0%
88%
13%
0%
0%
100%
0%
0%
0%
100%
0%
0%
0%
88%
13%
0%
0%
63%
0%
25%
13%
20
Table 6. Mean values (and standard deviations) of water chemistry measurements made during lake-wide biological
assessments of the eastern Finger Lakes performed in summer 2012.
Parameter
Waterbody
Canandaigua
Keuka
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Temperature
(oC)
23.7 (0.5)
25.9 (1.0)
24.3 (1.1)
25.8 (0.7)
24.3 (0.7)
22.6 (0.5)
26.8 (1.0)
Specific Conductivity
(umhos)
Dissolved
Oxygen(mg/L)
343.1 (5.6)
274.9 (7.6)
599.1 (8.2)
333.5 (16.5)
248.1 (7.9)
247.3 (6.4)
315.3 (18.9)
8.1 (0.3)
9.4 (1.4)
9.7 (1.6)
11.9 (2.7)
8.5 (1.4)
8.9 (1.3)
8.8 (1.2)
Dissolved
Oxygen (%
Sat)
95.1 (3.0)
115.9 (18.9)
116.2 (18.7)
146.0 (33.5)
102.0 (18.8)
102.8 (15.1)
111.1 (15.4)
pH
8.8 (0.1)
9.0 (0.2)
9.1 (0.2)
8.7 (0.4)
8.2 (0.2)
9.1 (0.1)
8.2 (0.3)
Table 7. Summary of macroinvertebrate metrics calculated from lake-wide samples collected from the seven eastern
Finger Lakes, New York, summer 2012.
Waterbody
Canandaigua
Keuka
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Overall Mean
Total Taxa
Mean
SD
23.63 5.423
27.88 10.22
14.25 5.175
23.9 5.087
27.5
4.87
25.88 4.612
18.5 6.437
23.1
#/Taxon
Mean
SD
14.09 3.434
12.86 5.214
26.08
13
13.54 2.912
11.41 1.868
12.61 3.204
15.88 5.898
15.2
ETO
Mean SD
5.4
4.2
28.9
28.5
0.4
0.7
14.7
12.2
16.4
20.1
133.9 76.6
23.1
25.4
31.8
Dom1
Mean SD
55.4
15.4
50.2
19.5
79.1
14.2
49.9
18.6
45.5
17.2
42.8
19.4
54.5
12.3
53.9
% Oligos
Mean SD
2.1
2.7
1.2
1.4
0.1
0.1
3.6
4.6
2.9
3.0
2.6
2.9
2.9
6.1
2.2
Non Ins %
Mean SD
91.7
6.7
76.8
18.7
97.6
4.0
79.0
9.4
73.4
15.8
40.4
30.0
72.6
25.0
76.0
Waterbody
Canandaigua
Keuka
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Overall Mean
CruMol Tax
Mean
SD
9.0
1.4
8.6
1.3
7.3
2.0
7.7
2.2
9.8
1.6
6.3
1.6
5.4
2.5
7.7
Shannon
Mean
SD
1.6
0.3
1.9
0.7
0.9
0.5
1.8
0.5
2.0
0.4
2.0
0.6
1.6
0.3
1.7
HBI
Mean
6.6
6.4
6.3
6.5
6.5
6.1
6.7
6.4
% Tol
Mean SD
32.4
16.9
28.9
11.8
14.6
10.3
30.5
19.6
30.2
10.5
31.4
25.9
28.8
23.0
28.1
% Shred
Mean SD
0.3
0.2
0.7
1.1
0.1
0.2
1.4
2.1
0.8
0.7
0.4
0.3
3.4
4.2
1.0
% Filt
Mean SD
17.4
14.8
11.7
11.1
7.2
9.4
8.8
8.0
17.6
12.6
12.2
6.7
13.1
9.1
12.6
21
SD
0.4
0.4
0.2
0.4
0.2
0.8
0.8
Table 8. Occurrence of invasive benthic macroinvertebrates in samples collected from each of 7 eastern Finger Lakes
in summer 2012. Occurrence based on the combined results of lake-wide samples, composite samples, and north-end
lake samples (from 4 lakes). Shaded cells indicate known prior records of occurrence, yet not detected in this study.
x
x
x
x
x
x
4
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
5
5+1 prior
3*
3+1 prior
3
3
x
x
x
x
TOTAL
Hemimysis sp.
Echinogammarus ischnus
Keuka
Seneca
Cayuga
Owasco
Skaneateles
Otisco
Dreissena polymorpha
x
Dreissena bugensis
Canandaigua
Corbicula fluminea
Cipangopaludina sp.
Waterbody
Bithynia tentaculata
Invasive taxon
*Note: A review of iMapInvasives in April 2014 found sightings of Bithynia tentaculata and
Hemimysis sp. in Cayuga Lake. Total should be 3+2 prior.
22
Table 9. Winter draw-down lake water levels relative to benthic macroinvertebrate sampling depths.
(Data compiled by Cayuga County Planning Department).
Lowest winter
water level
2011 - 2012
Water level
at time of
sampling
Elevation of benthic
interface
-1.0m to -0.5m
Sample area
exposed by
drawdown
Canandaigua
Keuka
687.2
712.35
687.98
713.78
684.7 - 686.34
710.5 - 712.14
No
No
Seneca
444.4
445.1
441.82 - 443.46
No
Cayuga
379
382.52 &
382.64
379.24 - 380.88 &
379.36 - 381.00
Yes
712.42
709.14 - 710.78
Partially
861.81
785.52
858.53 - 860.17
782.24 - 783.88
No
No
Lake
Owasco
Skaneateles
Otisco
710.43 (with
freezing temp)
861.79
785.85
23
Figure 1. Summary of six macroinvertebrate metrics calculated from three sample types collected from the seven
eastern Finger Lakes, New York, summer 2012. Error bars represent one standard deviation.
24
Figure 2. Summary of six macroinvertebrate metrics calculated from three sample types collected from the
seven eastern Finger Lakes, New York, summer 2012. Error bars represent one standard deviation.
25
Figure 3. Number of mayfly and caddisfly taxa identified from lake-wide samples collected in the Eastern
Finger Lakes in summer 2012.
10
Mayfly and Caddisfly Richness
9
8
Number of Taxa
7
6
5
Mayfly Richness
4
Caddisfly Richness
3
2
1
0
Lake
26
Figure 4. Relative abundance of major macroinvertebrate taxonomic groups from the seven Eastern Finger
Lakes, summer 2012, as determined from replicate lake-wide samples.
27
Figure 5. Number of invasive macroinvertebrate species sampled from seven Finger Lakes using three
different sampling approaches (lake-wide sampling, north-end lake sampling, and composite sampling).
Lake-wide results include total taxa collected from across all (8 or 10) individual lake-wide samples, northend results include total taxa collected from across all individual north-end samples, while composite sample
results are derived from a single composite sample.
6
Number of Invasive Species
Number of Taxa
5
4
3
Lake-Wide
2
North-End
Composite
1
Total
0
Lake
28
Appendix
29