US Long-Term Ecological Research Network

Little Rock Lake Experiment at North Temperate Lakes LTER: Zooplankton count 1983 - 2000

Abstract
The Little Rock Acidification Experiment was a joint project involving the USEPA (Duluth Lab), University of Minnesota-Twin Cities, University of Wisconsin-Superior, University of Wisconsin-Madison, and the Wisconsin Department of Natural Resources. Little Rock Lake is a bi-lobed lake in Vilas County, Wisconsin, USA. In 1983 the lake was divided in half by an impermeable curtain and from 1984-1989 the northern basin of the lake was acidified with sulfuric acid in three two-year stages. The target pHs for 1984-5, 1986-7, and 1988-9 were 5.7, 5.2, and 4.7, respectively. Starting in 1990 the lake was allowed to recover naturally with the curtain still in place. Data were collected through 2000. The main objective was to understand the population, community, and ecosystem responses to whole-lake acidification. Funding for this project was provided by the USEPA and NSF. Zooplankton samples are collected from the treatment and reference basins of Little Rock Lake at at two to nine depths using a 30L Schindler Patalas trap (53um mesh). Zooplankton samples are preserved in buffered formalin and archived. Data are summed over sex and stage and integrated volumetrically over the water column to provide a lake-wide estimate of organisms per liter for each species. Sampling Frequency: varies - Number of sites: 2
Core Areas
Dataset ID
251
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
We collect zooplankton samples at the deepest part of the lake using two different gear types. We take one vertical tow with a Wisconsin Net (80um mesh), and a series of Schindler Patalas (53um mesh) samples spanning the water column. All samples are preserved in cold 95percent EtOH. After collection we combine subsamples of the individual Schindler Patalas trap samples to create one hypsometrically pooled sample for each lakeordate. The individual depth samples are discarded after pooling except from one August sampling date per year. The Hypsometrically Pooled sample and the Wisconsin Net sample are archived in the UW Zoology museum. We count zooplankton in one or two subsamples, each representing 1.8L of lake water, of the hypsometrically pooled samples to calculate zooplankton abundance. We count one sample date per month from the open water season, and the February ice cover sample. We identify individuals to genus or species, take length measurements, and count eggs and embryos. Protocol log: 1981-May1984 -- a 0.5m high, 31L Schindler Patalas trap with 80um mesh net was used. Two Wisconsin Net tows were collected. Preservative was 12percent buffered formalin. June1984 -- changed to 53um mesh net on Schindler trap. July1986 -- began using the 2m high, 45L Schindler Patalas trap. Changed WI Net collection to take only one tow. 2001 -- changed zooplankton preservative from 12percent buffered formalin to 95percent EtOH. The number of sample dates per year counted varies with lake and year, from 5 datesoryear to 17 datesoryear. 1981-1983 -- pooled samples are of several types: Total Pooled (TP) were created using equal volume subsamples of the Schindler samples. Epi, Meta, Hypo pooled used equal volume subsamples from the Schindler samples collected from each of the thermal strata. Strata Pooled used equal volume subsamples from the Epi, Meta, Hypo pooled samples to create an entire lake sample. Hypsometrically Pooled (HP) is our standard, which uses subsample volumes weighted to represent the hypsometry of the lake.
Short Name
LRZOOP1
Version Number
3

Cascade Project at North Temperate Lakes LTER: Zooplankton 1984 - 2007

Abstract
Zooplankton data from 1984-1995. Sampled approximately weekly with two net hauls through the water column (30 cm diameter net, 80 um mesh). There have been 5 zooplankton counters during this period, so species-level identifications (TAX, below) are not as consistent as those for some of the other datasets. To standardize across counters, I have assigned higher-level taxonomic categories for a few "confusing" taxa; these identifications can be found in the column LLTAX, below. Sampling Frequency: varies Number of sites: 5
Core Areas
Dataset ID
79
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
for counting details see: Christensen, D.L., S.R. Carpenter, K.L. Cottingham, S.E. Knight, J.P. LeBouton, D.E. Schindler, N. Voichick, J.J. Cole, and M.L. Pace. 1996. Pelagic responses to changes in dissolved organic carbon following division of a seepage lake. Limnology and Oceanography 41:553-559.
Short Name
CZOOP1
Version Number
5

Primary Production and Species Richness in Lake Communities 1997 - 2000

Abstract
An understanding of the relationship between species richness and productivity is crucial to understanding biodiversity in lakes. We investigated the relationship between the primary productivity of lake ecosystems and the number of species for lacustrine phytoplankton, rotifers, cladocerans, copepods, macrophytes, and fish. Our study includes two parts: (1) a survey of 33 well-studied lakes for which data on six major taxonomic groups were available; and (2) a comparison of the effects of short- and long-term whole-lake nutrient addition on primary productivity and planktonic species richness Dodson, Stanley I., Shelley E. Arnott, and Kathryn L. Cottingham. 2000. The relationship in lake communities between primary productivity and species richness. Ecology 81:2662-79. Number of sites: 33
Creator
Dataset ID
222
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Our first goal was to understand the relationship between primary productivity and species richness for several groups of freshwater organisms. By species richness, we mean the number of species observed in a lake over a number of years. It is useful to have several years of observations because the number of species observed varies from year to year. We chose the total list of species (the asymptote of the collectors curve) as our index of species richness. The lakes studied as part of the U.S. Long-Term Ecological Research (LTER) Program are particularly valuable because they have been studied for two decades, and complete species lists exist for many kinds of organisms in these systems. LTER lake sites occur in northern and southern Wisconsin and northern Alaska (Toolik Lake). However, because there are fewer than 15 LTER lakes (and only seven with measured rates of primary productivity), we increased sample size by including data from additional well-studied lakes of similar size, but which span a greater range of primary productivity (see Table 1). These lakes have been studied for several years, and estimates of annual primary productivity exist for each lake. Some well-studied lakes were not included, such as those which lacked much of the crucial data, or lakes that were unusually turbid or saline. For example, Lake Okeechobee (Florida, USA) is turbid and exhibits a wide range of productivity levels, depending on the part of the lake sampled, while Marion Lake (British Columbia, Canada) has a flushing rate of only a few days (W. E. Neill, personal communication). Sampling design and protocol are not standardized among studies of lakes. For example, species identifications were done by different people, sampling period was quite variable, and the number of samples per lake was variable. Such heterogeneity reduces the accuracy and precision of relationships between productivity and species richness.Primary productivity.—Pelagic primary productivity (PPR) can be measured by the 14C method (Vollenweider 1974). This method gives a close approximation to gross primary productivity (GPP), but because some of the fixed carbon is respired quickly, the value obtained is less than GPP (Fee et al.1982). Point values of PPR are then integrated by depth and area to produce estimates of whole-lake annual primary productivity per cubic meter or square meter.Lake primary productivity is fundamentally different than productivity measured in other biomes (e.g., grasslands, forests). The 14C method measures available (gross) primary productivity more than utilized (net) production, which is what is normally measured in terrestrial systems. The 14C method is also a fairly direct measure of productivity, compared to the proxy methods (e.g., nutrient loading, biomass, climate, soil fertility) used in many studies.Sampling protocols for aquatic organisms.—Sampling protocols differed among taxonomic groups and lakes (e.g., Downing and Rigler 1984). For example, phytoplankton samples are taken by capturing (at most) a few liters of lake water, either from a specific depth or with a sampler that integrates water across a range of depths. Zooplankton are usually sampled by vertical tows (i.e., raising a net through the water column). Both zooplankton and phytoplankton samples are typically taken from the center of the lake, although replicate samples at different locations may be taken from larger lakes. Planktonic organisms are much smaller than the sampling device, and hundreds to hundreds of thousands of organisms are typically captured in a single sample. In contrast, aquatic macrophytes are sampled using quadrats and rake samples, or simply based on a walk around the lake, while fish are sampled using a variety of nets andoror electroshocking equipment. Criteria for species lists.—Species lists for fish, macrophytes, and pelagic phytoplankton, rotifers, cladocerans, and copepods were obtained from the literature and from unpublished data. We avoided lists restricted to only dominant or common species, and thus included only lists that were exhaustive. Few lakes had species lists for all six groups of organisms. However, we included any lake that had an estimate of the average annual primary productivity and had lists for at least three taxa.We standardized this database by developing criteria for inclusion of species in analyses. Phytoplankton lists included all prokaryotic and eukaryotic photosynthetic phytoplankton for which there were abundances of more than one organism per milliliter (a criterion also used by Lewis 1979). We included all nonsessile species caught in open water as pelagic rotifers. For the crustacean zooplankton (cladocerans and copepods), we followed the criteria of Dodson (1992). Species lists of macrophytes included all submerged, floating, or emergent species of flowering plants, including Typha, sedges, grasses, and duck weed. We did not include Isoetes or macroalgae such as Chara and Nitella as macrophytes. The fish list included all species reported from the lake, including introduced taxa. Fish species reported to occur in the watershed, but not in the lake (as in Pearse1920) were not considered part of the lakes biota.
Short Name
DODSON1
Version Number
26

Zooplankton Communities of Restored Depressional Wetlands in Wisconsin - North Temperate Lakes LTER 1998

Abstract
Wisconsin has lost approximately 2 million hectares of wetland since statehood (1848). Through the combined efforts of state and federal agencies and private groups focused primarily on wetland restoration for waterfowl habitat management or compensatory mitigation, a fairly substantial gain in wetland area has been achieved. Much of the wetland restoration effort in Wisconsin has occurred on formerly agricultural lands. However, due to the nature of the past disturbance and possible residual effects not corrected by simply returning surface waters to these lands, there is some question regarding the resultant wetland quality or biological integrity. In an effort aimed at developing tools to measure wetland gains in terms of quality or ecological integrity, the Wisconsin Department of Natural Resources (WDNR) initiated a study of biological communities on restored wetlands in Wisconsin. We report on the community of microcrustaceans and arthropods that can be collected with a plankton net in open water in wetlands. We examined zooplankton community structure in restored wetlands in terms of richness, taxonomic representation, and Daphnia sexual reproduction and related these metrics to attributes on wetlands representing least-disturbed conditions and agriculturally impacted wetlands. We sampled 56 palustrine wetlands distributed across Wisconsin. These wetland sites were categorized as agricultural, least-impacted, and restored (recently withdrawn from agricultural usage). The wetlands were reasonably homogeneous in many ways, so that taxon richness was not correlated with basin origin, presence of adjacent roads, presence or absence of fish, water chemistry, or the size of the open water. We identified a total of 40 taxa.. We conclude that restoration of wetland watersheds works. Withdrawal of the watershed from agricultural usage is followed by an increase in taxon richness, and the sites resembled least-impacted sites in about 6-7 years. Dodson, S. I. and R. A. Lillie. 2001. Zooplankton communities of restored depressional wetlands in Wisconsin, USA. Wetlands 21:292-300. Number of sites: 58
Core Areas
Creator
Dataset ID
225
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Dodson, S. I. and R. A. Lillie. 2001. Zooplankton communities of restored depressional wetlands in Wisconsin, USA. Wetlands 21:292-300.
Short Name
DODSON4
Version Number
20

Zooplankton of Small Lakes and Wetland Ponds in Wisconsin - North Temperate Lakes LTER 1996

Abstract
We sampled zooplankton communities from 54 small water bodies distributed throughout Wisconsin to evaluate whether a snap-shot of zooplankton community structure during early spring could be used for the purpose of differentiating lakes from wetlands. We collected a single set of zooplankton and water chemistry data during a one-month time window (synchronized from south to north across the state) from an open water site in each basin as a means to minimize and standardize sampling effort and to minimize cascading effects arising from predator-prey interactions with resident and immigrant aquatic insect communities. We identified 53 taxa of zooplankton from 54 sites sampled across Wisconsin. There was an average of 6.83 taxa per site. The zooplankton species were distributed with a great deal of independence. We did not detect significant correlations between number of taxa and geographic region or waterbody size. There was a significant inverse correlation between number of taxa and the concentration of calcium ion, alkalinity and conductivity. One pair of taxa, Lynceus brachyurus and Chaoborus americanus, showed a significant difference in average duration of sites of their respective occurrence. All other pairs of taxa had no significant difference in average latitude, waterbody surface area, total phosphorus, total Kjeldahl nitrogen, alkalinity, conductivity, calcium ion, sulfate, nitrate, silicate or chloride. Taxa were distributed at random among the sites - there were no statistically significant pairs of taxa occurring together or avoiding each other. Multivariate analysis of zooplankton associations showed no evidence of distinct associations that could be used to distinguish lakes from wetlands. Zooplankton community structure appears to be a poor tool for distinguishing between lakes and wetlands, especially at the relatively large scale of Wisconsin (dimension of about 500 km). The data suggest that a small body of water in Wisconsin could be classified as a wetland if it persists in the spring and summer for only about 4 months, and if it is inhabited by Lynceus brachyurus, Eubranchipus bundyi, and if Chaoborus americanus and Chydorus brevilabris are absent. Schell, Jeffery M., Carlos J. Santos-Flores, Paula E. Allen, Brian M. Hunker, Scott Kloehn, Aaron Michelson, Richard A. Lillie, and Stanley I. Dodson. 2001. Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin, U.S.A. Hydrobiologia 445:37-50 Number of sites: 54
Creator
Dataset ID
224
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Schell, Jeffery M., Carlos J. Santos-Flores, Paula E. Allen, Brian M. Hunker, Scott Kloehn, Aaron Michelson, Richard A. Lillie, and Stanley I. Dodson. 2001. Physical-chemical influences on vernal zooplankton community structure in small lakes and wetlands of Wisconsin, U.S.A. Hydrobiologia 445:37-50
Short Name
DODSON3
Version Number
25

Crustacean Zooplankton Species Richness in 66 North American Lakes 1992 - 1993

Abstract
Data from 66 North American lakes were collected to construct a model for predicting the number of crustacean zooplankton species expected in a lake. The chosen lakes have a range from 4 sq m to 80 x 10**9 sq m surface area, range from ultra-oligotrophic to hypereutrophic, and have zooplankton species lists based of several years of observation The number of crustacean zooplankton species in a lake is significantly correlated with lake size, average rate of photosynthesis (parabolic function) and the number of lakes within 20 km. A multiple linear regression model, using these three independent variables, explains approximately 75% of the variation in log species richness. Prediction of species richness is not enhanced by the knowledge of lake depth, salinity, elevation, latitude, longitude, or distance to nearest lake. The North American species area curve is statistically different from and steeper than the corresponding European curve.Number of sites: 69
Core Areas
Creator
Dataset ID
223
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Dodson, S. 1992. Predicting Crustacean Zooplankton Species Richness. Limnology and Oceanography 37:848-856.Dodson, S. 1991. Species richness of crustacean zoo- plankton in European lakes of different sizes. Int. Ver. Theor. Angew. Limnol. Verh. 24:1223-1229.
Short Name
DODSON2
Version Number
23

Biocomplexity at North Temperate Lakes LTER; Coordinated Field Studies: Zooplankton Presence/Absence 2001 - 2004

Abstract
Zooplankton samples were taken at approximately the deepest part of 58 lakes included in the "cross-lake comparison" segment of the Biocomplexity Project. The samples were from years 2001 through 2004. The study lakes are located in Vilas County, Wisconsin and were chosen to represent a range of positions on gradients of both human development and landscape position. Zooplankton samples were analyzed for planktonic crustacean and insect species. Number of sites: 58 Sampling Frequency: each site sampled once
Core Areas
Dataset ID
208
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Wisconsin Net samplesLower the Wisconsin net to the bottom sample depth ( top of the net should be one meter above the bottom). Pull it up slowly at a rate of about 3 seconds per meter. A slow haul prevents the net from pushing water and plankton away from the mouth of the net. To drain the cup swirl it until the water level is below the lower mesh window, then pour contents into the sample jar. Avoid inverting the cup while swirling, as you will lose the sample into the net. Rinse the inside of the cup with 95percent ETOH several times adding the rinse to the sample jar. Wait until the chemistry crew member is finished taking Temp or D.O. profile before taking the Wisconsin net sample, so as not to stir up the sediments. Take replicate sample.
Short Name
BIOZOOP1
Version Number
7

North Temperate Lakes LTER: Zooplankton - Madison Lakes Area 1997 - current

Abstract
Zooplankton samples for the 4 southern Wisconsin LTER lakes (Mendota, Monona, Wingra, Fish) have been collected for analysis by LTER since 1995 (1996 Wingra, Fish) when the southern Wisconsin lakes were added to the North Temperate Lakes LTER project. Samples are collected as a vertical tow using an 80-micron mesh conical net with a 30-cm diameter opening (net mouth: net length ratio = 1:3) consistent with sampling conducted by the Wisconsin Dept. Natural Resources in prior years. Zooplankton tows are taken in the deep hole region of each lake at the same time and location as other limnological sampling; zooplankton samples are preserved in 70% ethanol for later processing. Samples are usually collected with standard tow depths on most dates (e.g., 20 meters for Lake Mendota) but not always, so tow depth is recorded as a variate in the database. Crustacean species are identified and counted for Mendota and Monona and body lengths are recorded for a portion of each species identified (see data protocol for counting procedure); samples for Wingra and Fish lakes are archived but not routinely counted. Numerical densities for Mendota and Monona zooplankton samples are reported in the database as number or organisms per square meter without correcting for net efficiency. [Net efficiency varies from a maximum of about 70% under clear water conditions; net efficiency declines when algal blooms are dense (Lathrop, R.C. 1998. Water clarity responses to phosphorus and Daphnia in Lake Mendota. Ph.D. Thesis, University of Wisconsin-Madison.)] Organism densities in number per cubic meter can be obtained by dividing the reported square-meter density by the tow depth, although adjustments for the oxygenated depth zone during the summer and early fall stratified season is required to obtain realistic zooplankton volumetric densities in the lake's surface waters. Biomass densities can be calculated using literature formulas for converting organism body lengths reported in the database to body masses. Sampling Frequency: bi-weekly during ice-free season from late March or early April through early September, then every 4 weeks through late November; sampling is conducted usually once during the winter (depending on ice conditions). Number of sites: 4 Note: for a period between approximately 2011 and 2015, a calculation error caused density values to be significantly greater than they should have been for the entire dataset. That issue has been corrected.
Core Areas
Dataset ID
90
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
We collect zooplankton samples at the deepest part of the lake using two different gear types. We take one vertical tow with a Wisconsin Net (80um mesh), and a series of Schindler Patalas (53um mesh) samples spanning the water column. All samples are preserved in cold 95percent EtOH.After collection we combine subsamples of the individual Schindler Patalas trap samples to create one hypsometrically pooled sample for each lakeordate. The individual depth samples are discarded after pooling except from one August sampling date per year. The Hypsometrically Pooled sample and the Wisconsin Net sample are archived in the UW Zoology museum.We count zooplankton in one or two subsamples, each representing 1.8L of lake water, of the hypsometrically pooled samples to calculate zooplankton abundance. We count one sample date per month from the open water season, and the February ice cover sample. We identify individuals to genus or species, take length measurements, and count eggs and embryos.Protocol log: 1981-May1984 -- a 0.5m high, 31L Schindler Patalas trap with 80um mesh net was used. Two Wisconsin Net tows were collected. Preservative was 12percent buffered formalin.June1984 -- changed to 53um mesh net on Schindler trap.July1986 -- began using the 2m high, 45L Schindler Patalas trap. Changed WI Net collection to take only one tow.2001 -- changed zooplankton preservative from 12percent buffered formalin to 95percent EtOH.The number of sample dates per year counted varies with lake and year, from 5 datesoryear to 17 datesoryear.1981-1983 -- pooled samples are of several types: Total Pooled (TP) were created using equal volume subsamples of the Schindler samples. Epi, Meta, Hypo pooled used equal volume subsamples from the Schindler samples collected from each of the thermal strata. Strata Pooled used equal volume subsamples from the Epi, Meta, Hypo pooled samples to create an entire lake sample. Hypsometrically Pooled (HP) is our standard, which uses subsample volumes weighted to represent the hypsometry of the lake.
Short Name
NTLPL06
Version Number
31

North Temperate Lakes LTER: Zooplankton - Trout Lake Area 1982 - current

Abstract
Zooplankton samples are collected from the seven primary northern lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and bog lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) at two to nine depths using a 2m long Schindler Patalas trap (53um mesh) and with vertical tows using a Wisconsin net (20cm diameter, 80um mesh). Zooplankton samples are preserved in buffered formalin (until 2001) or 95% ethanol (2001 onwards). Subsamples of the individual Schindler trap samples are combined to create a hypsometrically pooled sample which is counted for copepods, cladocerans, and rotifers. Data are summed over sex and stage to provide a lake-wide estimate of organisms per liter for each species. A minimum of 5 samples per lake-year are counted. The data set also contains length measurements for copepods and cladocerans. The Wisconsin net sample and the pooled sample are archived in the UW Zoology museum. Each year one complete set of Schindler Patalas depth samples collected in August is also archived. From 1981 to August 1986 - used a 0.5m high Schindler Patalas trap. Sampling Frequency: every two weeks during ice-free season, every 5 weeks during ice-cover. Number of sites: 7
Core Areas
Dataset ID
37
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Schindler-Patalas trap samples are collected with a 2-meter high, 45L Schindler-Patalas trap with 53um mesh net at the deepest part of the lake. Samples are collected from specified target depths to include most or all of the water column, every two weeks during open water and every five weeks during ice cover. In addition, a vertical tow taken with an 80um mesh Wisconsin net is collected from the same location. Samples are preserved in the field with cold 95 percent EtOH.
For zooplankton counting, a hypsometrically pooled sample is created from subsamples of the individual Schindler Patalas samples. Subsample volumes are calculated using the hypsometric data for each lake, so that each subsample volume is proportional to the volume of lake water represented by the trap sample. A portion of the pooled sample is counted for copepods, cladocerans, and rotifers, identifying individuals to species or genus. All eggs are counted and length measurements are taken on copepods and cladocerans. Taxonomic resolution: A genus-only designation may mean a different species than the otherwise named species in that lake, or it may mean that the person counting only identified it to genus in that sample. Within one sample (same lake and date) it may be assumed that a genus only individual is a different species than other SameGenus/Named species in that count.
All records from 1981-1989 were modified in March 2015 to correct an error in how density had been calculated. Density values in many cases are significantly reduced. The table that was corrected in this case is dbmaker.zoop_all_density. Density values are modified from the original to final tables as they are summed or averaged over other variables (sample depth, replicate, and sex stage). The final table, where this website extracts density from, is dbmaker.zoop_allnl_summary_snap. Records after 1989 were already valid and did not require any modification.
Short Name
NTLPL03
Version Number
37

Cross Lake Comparison at North Temperate Lakes LTER - Zooplankton Biomass Study 2006

Abstract
This project investigates why zooplankton size, but not biomass, has been found to influence the phosphorus (TP) - chlorophyll a (chl a) relationship (Pace 1984, Carpenter et al. 1991, Carpenter et al. 2001).
Dataset ID
220
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Total phosphorus, chlorophyll a, and zooplankton samples were collected from 19 lakes in northeastern Wisconsin and Upper Michigan. Thirteen lakes are in Vilas County, WI (Star Lake, Anvil Lake, Stormy Lake, Camp Lake, Crab Lake, Little Crawling Stone Lake, Sparkling Lake, Lake Laura, Big Portage Lake, Crystal Lake, Tuesday Lake, Trout Lake, Lac du Lune, and Lynx Lake), one lake is in Oneida County, WI (Indian Lake) and 5 lakes lie within the University of Notre Dame Environmental Research Center (Peter Lake, Paul Lake, Tuesday Lake, Crampton Lake and Long Lake). The lakes were sampled in late May and June 2006. All sampled lakes lie within the coordinates 45 36 to 46 18 N and 89 00 to 89 54 W. Samples were collected from the deepest part of each lake. Lake information: Data collected on the sampledate include air temperature, an estimate of cloud cover, an estimate of wave height, maximum depth, secchi depth, and the depths of the epilimnion, metalimnion, and hypolimnion. Lakes identified as being located in UNDERC lie within the University of Notre Dame Environmental Research Center near Land O Lakes, Wisconsin, USA (89 32 W, 46 13 N). The location of the remaining lakes is identified by county - either Vilas or Oneida. Zooplankton Biomass: Five replicate zooplankton samples were collected from the deepest spot of each lake using vertical tows with a Wisconsin net (80 um mesh, 0.11 m radius). The tow was from 2 meters above the bottom of the lake to the surface. Zooplankton samples were preserved in 70percent ethanol. Each sample was drained through an 80 um mesh and sub-sampled three times using a 1 mL Hensen Stempel Pipette, and all zooplankton present in each subsample were identified down to genus or species. Thirty zooplankton of each genus or species in each 1 mL rep were measured using an ocular micrometer and a Leica MZ-8 dissecting microscope. To calculate biomass, the average weight for each species or genus per sample was applied to published dry weight- length regressions. Length-weight regressions (see methods) used to calculate biomass Zooplankton Lengths: Thirty zooplankton of each genus or species were measured using an ocular micrometer in a Leica MZ-8 dissecting microscope. All measurements are in mm. Note: Length measurements for Holopedium gibberum are of the post abdominal claw (between the setae natatores and the terminal claw). Total body length can be determined from the equation: Post abdominal claw length (um) equals 191.64 times Total Length (mm) plus 37.0 (Yan and Mackie 1986) Water Temperature/Dissolved Oxygen Profiles: A temperature and dissolved oxygen profile was taken on each lake on the sampling date Total Phosphorus and Total Nitrogen: Six samples were collected to determine the total phosphorus of each sampled lake. Triplicate 100-mL integrated samples were collected with a plastic tube (1.9 cm diameter) from the epilimnion. Discrete total phosphorus samples were collected with plastic tubing (0.6 cm) and a peristaltic pump from the middle of the metalimnion, the top of the hypolimnion and 1 meter above the bottom of the hypolimnion. Samples were preserved with 1 mL of Optima HCl and analyzed spectophotometrically for total phosphorus and total nitrogen. Some of the lakes were not completely stratified at the sampledate slightly altering the sampling method. In Crab Lake, Stormy Lake and Trout Lake the thermal profile made it difficult to determine the division between meta- and hypolimnion, so two additional samples were collected - from the metalimnion and from the top of the hypolimnion. In Anvil Lake, Big Portage Lake, Camp Lake, and Indian Lake, only one hypolimnion sample was collected because the lakes are shallow and were not completely stratified. Chlorophyll-a: Six integrated chlorophyll a samples (three epi- and three metalimnion) were collected from each lake using a plastic tube (1.9 cm diameter) and analyzed flourometrically. Sampling Frequency: Each of 19 lakes sampled once Number of sites: 19
Short Name
ZPBMASS
Version Number
22
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