US Long-Term Ecological Research Network

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/>
Core Areas
Dataset ID
417
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/>
Publication Date
Version Number
1

North Temperate Lakes LTER Regional Survey Macrophytes Plant Index 2015 - current

Abstract
The Northern Highlands Lake District (NHLD) is one of the few regions in the world with periodic comprehensive water chemistry data from hundreds of lakes spanning almost a century. Birge and Juday directed the first comprehensive assessment of water chemistry in the NHLD, sampling more than 600 lakes in the 1920s and 30s. These surveys have been repeated by various agencies and we now have data from the 1920s (UW), 1960s (WDNR), 1970s (EPA), 1980s (EPA), 1990s (EPA), and 2000s (NTL). The 28 lakes sampled as part of the Regional Lake Survey have been sampled by at least four of these regional surveys including the 1920s Birge and Juday sampling efforts. These 28 lakes were selected to represent a gradient of landscape position and shoreline development, both of which are important factors influencing social and ecological dynamics of lakes in the NHLD. This long-term regional dataset will lead to a greater understanding of whether and how large-scale drivers such as climate change and variability, lakeshore residential development, introductions of invasive species, or forest management have altered regional water chemistry. The purpose of the macrophyte survey is to identify, and quantify the types of aquatic plants within the various 28 regional survey lakes. The macrophyte survey consists of sampling macrophyte plants using a metal rake attached to a 15ft pole at approximately 140 spatially resolved points on a lake that are spread out in a grid like fashion, equally spaced from each other. Sampling locations were chosen such that the maximum depth at which macrophytes were surveyed was equal to or less than 15ft of water. Macrophyte sampling occurs in the latter part of the summer (after July 10) to ensure that macrophytes have had adequate time to grow and our sampling efforts capture the typical summer macrophyte community in each lake. Macrophyte sampling in these 28 lakes is ongoing and will be repeated approximately once every six years.
Core Areas
Dataset ID
338
Date Range
-
Methods
the protocol employed here is based on:
Hauxwell, J., S. Knight, K. Wagner, A. Mikulyuk, M. Nault, M. Porzky and S. Chase . 2010. Recommended baseline monitoring of aquat ic plants in Wisconsin : sampling design, field and laboratory procedures, data entry and analys is, and applica tions. Wisconsin Department of Natural Resources Bureau of Science Services, PUB-SS-1068 2010. Madison, Wisconsin, USA.
Version Number
13

North Temperate Lakes LTER: Sparkling Lake Macrophytes 2001 - 2010

Abstract
Macrophyte cover in Sparkling Lake sampled in late July from 2001 to 2010 from the waterline to a depth of 4 meters.
Core Areas
Dataset ID
272
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Macrophyte cover in Sparkling Lake was assessed in the third or fourth week of July from 2002-2004 and from 2007-2010. Eight transects were selected to correspond to trap survey sites for rusty crayfish and represent the range of macrophyte communities in the lake. These transects stretched from the waterline to a depth of 4 meters, running perpendicular to shore. Circular quadrats (1m2) were placed along each transect at 1 m longitudinal intervals, and observers using SCUBA estimated visually the percent cover of each macrophyte species within the quadrat. The sum of percent cover of all species within a quadrat does not necessarily add to 100; rather, this sum reflects the percentage of bottom substrate covered by macrophytes.
Version Number
22

Native and invasive species abundance distributions in lakes at North Temperate Lakes LTER 1979-2010

Abstract
These data were compiled from multiple sources. We collated data on the abundance or density of aquatic invasive and native species sampled in more than 20 sites using the same methods. To control for sampling methodology and allow comparisons among native and invasive species, we only included data where both invasive and native species from a taxonomic group were sampled using the same methods across multiple sites. Exceptions were made to include rusty crayfish (Orconectes rusticus) in its native range and zebra mussel (Dreissena polymorpha) data.
Core Areas
Dataset ID
268
Date Range
-
Metadata Provider
Methods
To control for sampling methodology and allow comparisons among native and invasive species, we only included data where both invasive and native species from a taxonomic group were sampled using the same methods across multiple sites. Exceptions were made to include rusty crayfish (Orconectes rusticus) in its native range and zebra mussel (Dreissena polymorpha) data. Native rusty crayfish data were obtained from (Jezerinac 1982). Zebra mussel data were mainly obtained from a meta-analysis (Naddafi et al. 2011) which compiled data from 55 European and 13 North American sites from 1959-2004. Additional densities from North America were compiled from multiple primary literature sources (Table S3). All zebra mussel records were presented as number per m2 and are from their invaded range; we did not include native mussel data.Crayfish data were obtained from multiple sources. Crayfish were collected in Wisconsin, USA during summers of 2002-2010 from lakes in the Northern Highlands Lake District following their protocol for crayfish collection. Crayfish were sampled in Wisconsin streams tributary to Lake Michigan from 2007-2010 using 10 gee-style minnow traps per site baited with chicken livers and set overnight. Swedish crayfish were sampled using 30 minnow traps baited with frozen fish in lakes and streams of southern Sweden from 2001-2003 as described in (Nystrom et al. 2006). Washington crayfish were collected from 100 lakes in the Puget Sound Lowlands region of Washington State, USA between 2007 and 2009 from mid-June to early October of each year. At each lake, the investigators set 20 minnow traps baited with fish-based dog food. Traps were deployed in four clusters of five traps each and recovered the following day. All crayfish densities are presented as number per trap per day, with the exception of native range rusty crayfish data, which were reported as number per site (Jezerinac 1982) and excluded from all comparisons that depend on sampling units.Wisconsin fish data were collected from streams throughout the state from 2005-2010 using either a backpack or towboat electrofisher with pulsed DC current in wadeable (less than1m depth) streams for a minimum of 15 minutes. For Wisconsin trout species, locations sampled within 10 years following a stocking event of that species were excluded. Lamprey data were collected from 2008-2010 from Great Lakes tributaries using backpack electrofishers following standardized methods as a part of the sea lamprey assessment program of the United States Fish and Wildlife Service and Department of Fisheries and Oceans, Canada. North American fish densities are presented as number per minute of sampling. Swedish fish data were collected using backpack electrofishing between 1980 and 2010 from streams in Vasterbotten county, northern Sweden, and were obtained from the Swedish Electrofishing REgister (SERS), www.fiskeriverket.se, and are reported as number per 100 m of stream.Snail data were collected in 2006 from lakes in the Northern Highlands Lake District in Wisconsin as described by (Solomon et al. 2010), and densities are presented as number per two m2. Aquatic plant data were collected using a systematic grid-based point-intercept sampling methodology to record macrophyte frequency of occurrence in 242 Wisconsin lakes from 2005-2008. Aquatic plant presence absence was recorded from a boat using a double-sided rake sampler at each point on a sampling grid as described in (Mikulyuk et al. 2010). Density data are presented as proportion of sites within lake littoral zone where a species was present.For all data, if multiple records existed from the same location, we used the most recent record. If replicate samples existed within the same site on the same sampling date, the mean value was used.
Version Number
22

North Temperate Lakes LTER: Macrophyte Species at Quadrat Level - Trout Lake 1993 - current

Abstract
These data are collected to document and characterize the submersed macrophytes of Trout Lake, to evaluate the long-term stability of this component, and to interface with investigations of other compartments of the ecosystem. Four sites along the shoreline of Trout Lake have been sampled annually in August along permanent line transects. These are quadrat-species level data. This dataset only contains information on species that were present. It includes a row for every species-quadrat present. If a quadrat is missing, that quadrat was either empty or was not sampled. Sampling Frequency: annually during summer Number of sites: 4
Core Areas
Dataset ID
26
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Sites are designated according to the NTL numbering scheme established for the shoreline of the south basin of Trout Lake and its islands. The four sites (Trout-07, 46.01809769, -89.65571661; Trout-31, 46.0430698, -89.67157974; Trout-50, 46.01729465, -89.69461296; Trout-56, 46.01921135, -89.6813004) used by the macrophyte component are also used in the NTL fish and crayfish sampling. The site descriptions specify a transect line along which presence or absence data is recorded for all macrophyte species. A 0.25 M2 ring placed at 1 meter intervals (except site 7 - 0.5 to 1 M depth where the ring is placed at 2 meter intervals) along the transect designates the sampling quadrat. Using SCUBA, species data are recorded along with the total number of quadrats encountered between the following depth intervals: 0.5-1 M, 1-2 M, 2-3 M and 3-5 M. These depth intervals have been permanently established with markers consisting of a commercial Earth Anchor set in the lake bottom with 2 floats secured to it near the bottom. Large boat bumpers are used on the anchors at 3 and 5 meters. Between 28 and 52 quadrats are examined within each depth interval at each site.
Pre-1987 Data. In 1987, permanent line transects were established at each of the sites. Biomass samples and line transects observed before 1987 were set by more general descriptions at the site and were not identical year to year.
Publication Date
Short Name
NTLMP06
Version Number
24

North Temperate Lakes LTER: Macrophyte Richness - Trout Lake 1993 - current

Abstract
These data are collected to document and characterize the submersed macrophytes of Trout Lake, to evaluate the long-term stability of this component, and to interface with investigations of other compartments of the ecosystem. Four sites along the shoreline of Trout Lake have been sampled annually in August along permanent line transects. These data are quadrat level data. This dataset includes a row for every quadrat sampled. The RICHNESS field contains the number of species present (set to zero if the quadrat was empty). If a row is missing, that quadrat was not sampled Sampling Frequency: annually during summer Number of sites: 4
Dataset ID
28
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Sites are designated according to the NTL numbering scheme established for the shoreline of the south basin of Trout Lake and its islands. The four sites (Trout-07, 46.01809769, -89.65571661; Trout-31, 46.0430698, -89.67157974; Trout-50, 46.01729465, -89.69461296; Trout-56, 46.01921135, -89.6813004) used by the macrophyte component are also used in the NTL fish and crayfish sampling. The site descriptions specify a transect line along which presence or absence data is recorded for all macrophyte species. A 0.25 M2 ring placed at 1 meter intervals (except site 7 - 0.5 to 1 M depth where the ring is placed at 2 meter intervals) along the transect designates the sampling quadrat. Using SCUBA, species data are recorded along with the total number of quadrats encountered between the following depth intervals: 0.5-1 M, 1-2 M, 2-3 M and 3-5 M. These depth intervals have been permanently established with markers consisting of a commercial Earth Anchor set in the lake bottom with 2 floats secured to it near the bottom. Large boat bumpers are used on the anchors at 3 and 5 meters. Between 28 and 52 quadrats are examined within each depth interval at each site.
Pre-1987 Data. In 1987, permanent line transects were established at each of the sites. Biomass samples and line transects observed before 1987 were set by more general descriptions at the site and were not identical year to year.
Short Name
NTLMP08
Version Number
24

North Temperate Lakes LTER: Macrophyte Transects - Trout Lake 1982 - current

Abstract
These data are collected to document and characterize the submersed macrophytes of Trout Lake to evaluate the long-term stability of this component and to interface with investigations of other compartments of the ecosystem. Four sites along the shoreline of Trout Lake have been sampled annually in August along permanent line transects. This dataset includes species presence/absence and transect summary data by depth along the transect. This information is useful in determining the annual variability of the submersed macrophytes and providing information on the effects of the invasion of an introduced crayfish Sampling Frequency: annually during summer Number of sites: 4
Dataset ID
22
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Sites are designated according to the NTL numbering scheme established for the shoreline of the south basin of Trout Lake and its islands. The four sites (Trout-07, 46.01809769, -89.65571661; Trout-31, 46.0430698, -89.67157974; Trout-50, 46.01729465, -89.69461296; Trout-56, 46.01921135, -89.6813004) used by the macrophyte component are also used in the NTL fish and crayfish sampling. The site descriptions specify a transect line along which presence or absence data is recorded for all macrophyte species. A 0.25 M2 ring placed at 1 meter intervals (except site 7 - 0.5 to 1 M depth where the ring is placed at 2 meter intervals) along the transect designates the sampling quadrat. Using SCUBA, species data are recorded along with the total number of quadrats encountered between the following depth intervals: 0.5-1 M, 1-2 M, 2-3 M and 3-5 M. These depth intervals have been permanently established with markers consisting of a commercial Earth Anchor set in the lake bottom with 2 floats secured to it near the bottom. Large boat bumpers are used on the anchors at 3 and 5 meters. Between 28 and 52 quadrats are examined within each depth interval at each site.
Pre-1987 Data. In 1987, permanent line transects were established at each of the sites. Biomass samples and line transects observed before 1987 were set by more general descriptions at the site and were not identical year to year.
Publication Date
Short Name
NTLMP02
Version Number
47

North Temperate Lakes LTER: Macrophyte Biomass in Trout Lake Summary 1983 - current

Abstract
These data are collected to document and characterize the submersed macrophytes of Trout Lake, to evaluate the long-term stability of this component, and to interface with investigations of other compartments of the ecosystem. Four sites along the shoreline of Trout Lake have been sampled annually in August along permanent line transects. This dataset includes biomass per m2 for individual species summarized by depth along the transect. Derived data include the mean and standard deviation of macrophyte biomass. These data are useful in determining the annual variability of the submersed macrophytes and providing information on the effects of the invasion of an introduced crayfish. Sampling Frequency: annually during summer Number of sites: 4
Core Areas
Dataset ID
25
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Sites are designated according to the NTL numbering scheme established for the shoreline of the south basin of Trout Lake and its islands. The four sites (Trout-07, 46.01809769, -89.65571661; Trout-31, 46.0430698, -89.67157974; Trout-50, 46.01729465, -89.69461296; Trout-56, 46.01921135, -89.6813004) used by the macrophyte component are also used in the NTL fish and crayfish sampling. Five replicate quadrats (0.25 M2) are harvested for all above ground biomass at each site at each of three nominal depths: 1.5 M, 2.5 M and 4 M. Samples are removed along a line parallel to shore - located midway between sites for cover estimates. Four sites with 3 depths and 5 replicates yields 60 samples. In the lab, samples are separated by species and are dried and weighed. From 1989 to 2008 plants were placed in labeled paper bags oven dried, and weights recorded. Biomass weights were determined by weighing dried plants in paper bags and using an average tare for the bags. Consequently, values in the data base can be negative and should be considered as present in very small amounts.
Pre-1987 Data. In 1987, permanent line transects were established at each of the sites. Biomass samples and line transects observed before 1987 were set by more general descriptions at the site and were not identical year to year.
Publication Date
Short Name
NTLMP05
Version Number
25

North Temperate Lakes LTER: Macrophyte Biomass - Madison Lakes Area 1995 - current

Abstract
Macrophytes are sampled in Lakes Mendota, Monona, Wingra, and Fish. In the Madison area surveys are conducted from a boat at stations located at depths from 1 to 4 meters at 0.5-m intervals along transects perpendicular to the lake shoreline. Macrophyte total plant mass and the total filamentous algae mass is measured as fresh weight by standardized rake method. Sampling Frequency: annually during summer (June - August) Number of sites: 4
Core Areas
Dataset ID
24
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Aquatic macrophytes are sampled from a boat at stations located at depths from 1 to 4 meters at 0.5-m intervals along transects perpendicular to the lake shoreline of the four primary study lakes in the Madison area (Lakes Mendota, Monona, and Wingra, and Fish Lake) from June to August. A weighted, double-headed garden rake is cast off the front left, front right, rear left, and rear right of the boat and then dragged approximately 2 meters across the bottom by means of an attached line. The total plant mass and the total filamentous algae mass in each tow is measured. To the maximum extent possible, water is squeezed from the plants to minimize the amount of water present in the final weight. Weights are recorded in the boat using field scales. Weights from the 4 rake casts at each station can be averaged to compute overall average weights for plant mass and for filamentous algae mass at the station.
Detailed Macrophyte Sampling description.
Using the site book and the depth measuring pole, move to the 1 meter depth mark and throw both anchors. From the Macrophyte Depth Table, find the distance to throw out the rake and the meter mark that the line should be drawn to. The table is calculated to determine the starting and ending meter marks to draw in the line to allow the rake to drag 2 meters on the lake bottom. Pull the rake quickly out of the water. If a significant amount of dirt has been brought up with the plants (i.e. the weight of the dirt will add significantly to the total weight), wash the plants. Depending on the volume of the plants, wash them either by keeping them in your hands and dunking them in the lake or by putting them in a bucket with drain holes. Separate the filamentous algae from the rest of the plant material. Squeeze out as much water as possible (it may be necessary to divide up the plant material into portions to effectively squeeze out the water). Weigh the plant material (minus the filamentous algae) and record the total weight. Weigh the filamentous algae and record the weight. Repeat the above steps until 4 rake tosses have been thrown. Move to the next half-meter depth. Macrophytes are collected at each half-meter water depth from 1 meter to 4 meters.
Publication Date
Short Name
NTLMP04
Version Number
27

North Temperate Lakes LTER: Macrophyte Rating - Madison Lakes Area 1995 - current

Abstract
Macrophytes are sampled in Lakes Mendota, Monona, Wingra, and Fish. In the Madison area surveys are conducted from a boat at stations located at depths from 1 to 4 meters at 0.5-m intervals along transects perpendicular to the lake shoreline. Macrophyte species coverage is determined by standardized rake method. Sampling Frequency: annually during summer (June - August) Number of sites: 4

Dataset ID
23
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Aquatic macrophytes are sampled from a boat at stations located at depths from 1 to 4 meters at 0.5-m intervals along transects perpendicular to the lake shoreline of the four primary study lakes in the Madison area (Lakes Mendota, Monona, and Wingra, and Fish Lake) from June to August. A weighted, double-headed garden rake is cast off the front left, front right, rear left, and rear right of the boat and then dragged approximately 2 meters across the bottom by means of an attached line. For each rake cast, filamentous algae and any aquatic macrophyte species present are assigned a density rating from 0-5 based on the extent of coverage of the upper rake head. Determination of extent of coverage involves judgment of the surveyor as to the number of rake teeth and area of teeth covered by each species. It is necessary to separate plants to assess individual species coverage. Ratings from the 4 rake casts at each station can be averaged to compute an overall density rating for each species found at the station.
Detailed Macrophyte Sampling description.
Using the site book and the depth measuring pole, move to the 1 meter depth mark and throw both anchors. From the Macrophyte Depth Table, find the distance to throw out the rake and the meter mark that the line should be drawn to. The table is calculated to determine the starting and ending meter marks to draw in the line to allow the rake to drag 2 meters on the lake bottom. Pull the rake quickly out of the water. Before removing the plant material from the rake, drape the long strands over the rake and gently push the plant material down on the rake. Assign a rake rating (from 1 to 5) depending on how much the plant material covers the rake prongs. The rake prongs are painted in 20 percent increments. If the plant material only covers the lowest 20 percent of the rake prongs, assign the rake rating a 1. If the plant material covers between 20 percent and 40 percent of the rake prongs, the rake rating is a 2, and so on. If a significant amount of dirt has been brought up with the plants (i.e. the weight of the dirt will add significantly to the total weight), wash the plants. Separate the filamentous algae from the rest of the plant material. Separate and identify the individual plant species, throwing out any dead plant material. Give the filamentous algae and each plant species a rake rating (note that it is often necessary to visualize how much space each species would take up on the rake prongs rather than actually placing each species onto the rake). If a plant species can not be identified, take a sample back to the lab by putting it in a ziplock bag with a small amount of water and temporarily storing it in a cooler. Repeat the above steps until 4 rake tosses have been thrown. Normally 2 rake tosses are thrown out each side of the boat to an area where the water depth is known to be at the desired depth. Move to the next half-meter depth. Macrophytes are collected at each half-meter water depth from 1 meter to 4 meters.
Publication Date
Short Name
NTLMP03
Version Number
29
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