Aquatic snail and macrophyte abundance and richness data for ten lakes in Vilas County, WI, USA, 1987-2020
Abstract
Data accompanying the paper Szydlowski et al. "Three decades of lake monitoring
reveals community recovery after population declines of invasive rusty crayfish (Faxonius
rusticus)." Macrophytes and snails were sampled in ten lakes in Vilas County, Wisconsin, USA
during summer sampling events in 1987, 2002, 2011, and 2020. Lakes had varying levels of
invasion by F. rusticus, which affected measures of macrophytes and snails. Macrophytes were
sampled using a point-intercept transect method and snails were sampled using different
sampler types which were dependent on substrate. Macrophytes were sampled at 6-14 sites per
lake and snails were sampled at 16-31 sites per lake. Overall, this dataset provides abundance
and richness data for over 25 species of snails and over 40 species of macrophytes in north
temperate lakes.<br/>
reveals community recovery after population declines of invasive rusty crayfish (Faxonius
rusticus)." Macrophytes and snails were sampled in ten lakes in Vilas County, Wisconsin, USA
during summer sampling events in 1987, 2002, 2011, and 2020. Lakes had varying levels of
invasion by F. rusticus, which affected measures of macrophytes and snails. Macrophytes were
sampled using a point-intercept transect method and snails were sampled using different
sampler types which were dependent on substrate. Macrophytes were sampled at 6-14 sites per
lake and snails were sampled at 16-31 sites per lake. Overall, this dataset provides abundance
and richness data for over 25 species of snails and over 40 species of macrophytes in north
temperate lakes.<br/>
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Core Areas
Dataset ID
417
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LTER Keywords
Methods
Sampling methods are described by Szydlowski et al. "Three decades of lake
monitoring reveals community recovery after population declines of invasive rusty crayfish
(Faxonius rusticus)," but are provided here for convenience. Instrumentation is further
documented in the supplementary information of the paper. Macrophytes were sampled during
July and August at a subset of crayfish sampling sites within our ten study lakes (n =
6–14 sites per lake) that were selected in 1987 to capture a variety of substrates and
both east and west sun exposure. Sampling depths were randomly assigned to sites during
initial sampling in 1987 as either 0.75 m, ½ of Secchi depth, or ¾ of Secchi depth, with
1987 Secchi depths used for all subsequent sampling years for macrophyte surveys. We
followed the line-intercept method to sample macrophytes, using snorkeling and SCUBA to
visually identify and determine the presence or absence of macrophyte species along a 25 m
transect set parallel to shore at the pre-determined depth for each sampling site.
Transects were marked at 1 m intervals, with the first 10 cm of each interval marked by a
band of tape. Divers moved along the transect recording the presence or absence of each
macrophyte species crossing the vertical plane of each 10 cm band. The line-intercept
method allowed us to obtain a measure of both macrophyte species richness and abundance.
Because just presence or absence of macrophyte species was recorded, and only at each 10
cm band, our measurements provide an index for abundance and a minimum estimate for
species richness. Freshwater snails were sampled at locations historically sampled for
crayfish (n = 24 or 36 sites per lake) between late June and early August. As with
macrophytes, snails were sampled at randomly assigned depths of either 0.75 m, ½ of Secchi
depth, or ¾ of Secchi depth. While the same absolute depths were used in 1987 and 2002
based on 1987 Secchi values, depths in 2011 and 2020 were determined using year-specific
Secchi values. Most sampling depths in 2011 and 2020 varied only slightly from the 1987
and 2002 values, but in two lakes the change in sampling depth was greater than one meter
due to larger shifts in water clarity. The greatest changes in sampling depth (2.7 m in
Papoose Lake and 1.5 m in Little John Lake) occurred at the ¾ Secchi depth sites, whereas
the ½ Secchi depth sites were less affected by the change in water clarity in these two
lakes. We sampled snails using methods and equipment designed for each habitat type
present in our study lakes (soft substrates, macrophytes, and cobble). For soft substrates
such as sand and muck (flocculent sediment or sediment rich in organic material), we used
a cylindrical polyvinyl chloride (PVC) sediment corer (0.018 m2), which we used to take a
5 cm sediment core. For sites with soft substrates where macrophytes were present, we used
a modified PVC sampler of the same size but with two hinged PVC halves, and a net made of
1-mm mesh attached to the top. We carefully closed the two halves of the PVC sampler
around macrophytes growing at the surface and zippered the mesh net around taller
macrophytes before pushing the corer into the sediment to collect a 5 cm core. Collecting
the macrophyte material along with the sediment allowed us to sample any snails on the
macrophytes along with those in the sediment. At the water’s surface we sieved (with 1 mm
mesh) all cores from soft substrates to remove fine sediments and large particles and
picked through macrophyte material for snails. Finally, for cobble habitats, we placed a
ring (0.1 or 0.5 m2) on the substrate at each site to define a sampling area. In 1987 and
2002, the 0.1 m2 ring was used for sites with a high density of snails, and the 0.5 m2
ring was used for sites with a low density of snails. In 2011 and 2020, we used the 0.5 m2
ring at all sites. We gently collected the surface layer of rocks within the sampling ring
and briefly brought the rocks to the surface, where we scraped attached material into a
collection pan and funneled it through a 1 mm mesh sieve to gather snails. We stored
snails collected using all sampling methods in 70% ethanol for later identification. In
the lab, we picked snails from all samples and identified them to species or genus (for
Physella sp.) according to Burch (1989) and Johnson et al. (2013), with revisions for
Lymnaeidae (Hubendick 1951) and Planorbidae (Hubendick and Rees 1955). We calculated snail
abundance as density to account for differences between the sediment corers and the rings
in area sampled. Snail samples from 1987 were lost in a laboratory flood, but specimens
from 2002 and 2011 are vouchered at the Notre Dame Museum of Biodiversity in Notre Dame,
Indiana, USA. Specimens from 2020 are vouchered at the Illinois Natural History Survey
Mollusk Collection at the University of Illinois in Champaign, Illinois, USA. In 2020, we
were not able to sample macrophytes and snails using SCUBA due to limitations from the
COVID-19 pandemic. Therefore, we excluded a small portion of deeper sites (approximately
2% of total macrophyte sites and 13% of total snail sites) that could not be sampled
accurately and safely while snorkeling. In addition, because of a few lost samples, data
from previous sampling years were not always available for each site. Consequently, in our
datasets of macrophytes and snails, we only include sites for which we had data in all
four sampling years (n = 100 sites/year for macrophytes, n = 208 sites/year for snails).
In our snail data, we only included snails which were alive at the time of sampling (i.e.,
we did not include empty shells).<br/>
monitoring reveals community recovery after population declines of invasive rusty crayfish
(Faxonius rusticus)," but are provided here for convenience. Instrumentation is further
documented in the supplementary information of the paper. Macrophytes were sampled during
July and August at a subset of crayfish sampling sites within our ten study lakes (n =
6–14 sites per lake) that were selected in 1987 to capture a variety of substrates and
both east and west sun exposure. Sampling depths were randomly assigned to sites during
initial sampling in 1987 as either 0.75 m, ½ of Secchi depth, or ¾ of Secchi depth, with
1987 Secchi depths used for all subsequent sampling years for macrophyte surveys. We
followed the line-intercept method to sample macrophytes, using snorkeling and SCUBA to
visually identify and determine the presence or absence of macrophyte species along a 25 m
transect set parallel to shore at the pre-determined depth for each sampling site.
Transects were marked at 1 m intervals, with the first 10 cm of each interval marked by a
band of tape. Divers moved along the transect recording the presence or absence of each
macrophyte species crossing the vertical plane of each 10 cm band. The line-intercept
method allowed us to obtain a measure of both macrophyte species richness and abundance.
Because just presence or absence of macrophyte species was recorded, and only at each 10
cm band, our measurements provide an index for abundance and a minimum estimate for
species richness. Freshwater snails were sampled at locations historically sampled for
crayfish (n = 24 or 36 sites per lake) between late June and early August. As with
macrophytes, snails were sampled at randomly assigned depths of either 0.75 m, ½ of Secchi
depth, or ¾ of Secchi depth. While the same absolute depths were used in 1987 and 2002
based on 1987 Secchi values, depths in 2011 and 2020 were determined using year-specific
Secchi values. Most sampling depths in 2011 and 2020 varied only slightly from the 1987
and 2002 values, but in two lakes the change in sampling depth was greater than one meter
due to larger shifts in water clarity. The greatest changes in sampling depth (2.7 m in
Papoose Lake and 1.5 m in Little John Lake) occurred at the ¾ Secchi depth sites, whereas
the ½ Secchi depth sites were less affected by the change in water clarity in these two
lakes. We sampled snails using methods and equipment designed for each habitat type
present in our study lakes (soft substrates, macrophytes, and cobble). For soft substrates
such as sand and muck (flocculent sediment or sediment rich in organic material), we used
a cylindrical polyvinyl chloride (PVC) sediment corer (0.018 m2), which we used to take a
5 cm sediment core. For sites with soft substrates where macrophytes were present, we used
a modified PVC sampler of the same size but with two hinged PVC halves, and a net made of
1-mm mesh attached to the top. We carefully closed the two halves of the PVC sampler
around macrophytes growing at the surface and zippered the mesh net around taller
macrophytes before pushing the corer into the sediment to collect a 5 cm core. Collecting
the macrophyte material along with the sediment allowed us to sample any snails on the
macrophytes along with those in the sediment. At the water’s surface we sieved (with 1 mm
mesh) all cores from soft substrates to remove fine sediments and large particles and
picked through macrophyte material for snails. Finally, for cobble habitats, we placed a
ring (0.1 or 0.5 m2) on the substrate at each site to define a sampling area. In 1987 and
2002, the 0.1 m2 ring was used for sites with a high density of snails, and the 0.5 m2
ring was used for sites with a low density of snails. In 2011 and 2020, we used the 0.5 m2
ring at all sites. We gently collected the surface layer of rocks within the sampling ring
and briefly brought the rocks to the surface, where we scraped attached material into a
collection pan and funneled it through a 1 mm mesh sieve to gather snails. We stored
snails collected using all sampling methods in 70% ethanol for later identification. In
the lab, we picked snails from all samples and identified them to species or genus (for
Physella sp.) according to Burch (1989) and Johnson et al. (2013), with revisions for
Lymnaeidae (Hubendick 1951) and Planorbidae (Hubendick and Rees 1955). We calculated snail
abundance as density to account for differences between the sediment corers and the rings
in area sampled. Snail samples from 1987 were lost in a laboratory flood, but specimens
from 2002 and 2011 are vouchered at the Notre Dame Museum of Biodiversity in Notre Dame,
Indiana, USA. Specimens from 2020 are vouchered at the Illinois Natural History Survey
Mollusk Collection at the University of Illinois in Champaign, Illinois, USA. In 2020, we
were not able to sample macrophytes and snails using SCUBA due to limitations from the
COVID-19 pandemic. Therefore, we excluded a small portion of deeper sites (approximately
2% of total macrophyte sites and 13% of total snail sites) that could not be sampled
accurately and safely while snorkeling. In addition, because of a few lost samples, data
from previous sampling years were not always available for each site. Consequently, in our
datasets of macrophytes and snails, we only include sites for which we had data in all
four sampling years (n = 100 sites/year for macrophytes, n = 208 sites/year for snails).
In our snail data, we only included snails which were alive at the time of sampling (i.e.,
we did not include empty shells).<br/>
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Version Number
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