US Long-Term Ecological Research Network

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

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

Abstract
These data are collected to document and characterize the submersed macrophytes of Trout Lake and to evaluate their long-term dynamics and interactions with 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 m^2 for individual species at three depths along the transect. 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
21
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
NTLMP01
Version Number
26

North Temperate Lakes LTER: Pelagic Macroinvertebrate Summary 1983 - current

Abstract
This is a summary of dataset NTL 13. Derived data include the mean and standard deviation of the number of each species captured as well as the mean and standard deviation of the density of individuals on both an areal and volumetric basis.
Five vertical tows are collected after dark at the deepest point of each of the seven primary lakes in the Trout Lake area (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and bog lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) using a 1-m diameter, 1-mm mesh net. On Trout Lake four additional sites are sampled, where depths are approximately at 10 m, 15 m, 20 m, and 25 m, with three tows taken at each site. Samples are preserved, and later counted in their entirety for Chaoborus spp., Leptodora kindtii, Mysis relicta, and Bythotrephes longimanus. Sampling Frequency: annually. Number of sites: 11
Core Areas
Dataset ID
14
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Summary values are calculated from the number of individuals counted in each tow sample, diameter of net mouth, and depth of vertical tow.
Short Name
NTLIP02
Version Number
33

North Temperate Lakes LTER Pelagic Macroinvertebrate Abundance 1983 - current

Abstract
Pelagic macroinvertebrates are collected at night from the deepest location of each of the seven primary lakes in the Trout Lake area (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes and bog lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) by vertical tow with a 1-m diameter, 1-mm mesh net. On Trout Lake four additional sites are sampled, where depths are approximately 10m, 15m, 20m, and 25m. Sampling is once per year in the summer, with replicate tows collected on each lake. These tows target the large invertebrate planktivore component of the pelagic zooplankton community. This data set contains the number of individuals in each tow sample of four taxonomic groups: Chaoborus spp. (differentiating between larvae and pupae), Leptodora kindtii, Mysis relicta, and Bythotrephes longimanus. Trout Lake was the only lake sampled in 2020. Sampling Frequency: annually. Number of sites: 11
Core Areas
Dataset ID
13
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Vertical tows are collected after dark with a 1-meter diameter, 1-mm mesh net, with each lake sampled once between mid July and early August. Sampling stations are at the deepest location in each lake, with Trout Lake having four additional sampling stations at depths of 10m, 15m, 20m, and 25m. Five replicate tows are collected at the deep stations, and three replicate tows from each of the additional Trout Lake stations. Samples are preserved, and later counted in their entirety for Chaoborus spp. (differentiating between larvae and pupae), Leptodora kindtii, Mysis relicta, and Bythotrephes longimanus. One tow from each lake/station is archived in the UW Zoology museum.
Short Name
NTLIP01
Version Number
33

North Temperate Lakes LTER: Fish Species Richness 1981 - current

Abstract
This data set is a derived data set based on fish catch data. Data are collected annually to enable us to track the fish assemblages of eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish). Sampling on Lakes Monona, Wingra, and Fish started in 1995; sampling on other lakes started in 1981. Sampling is done at six littoral zone sites per lake with seine, minnow or crayfish traps, and fyke nets; a boat-mounted electrofishing system samples three littoral transects. Vertically hung gill nets are used to obtain two pelagic samples per lake from the deepest point. A trammel net samples across the thermocline at two sites per lake. In the bog lakes only fyke nets and minnow traps are deployed. Parameters measured include species-level identification and lengths for all fish caught, and weight and scale samples from a subset. Derived data sets include species richness, catch per unit effort, and size distribution by species, lake, and year. Species richness for a lake is the number of fish species caught in that lake during the annual fish sampling. Hybrids captured are only included in the richness value if neither of the two hybridized species are caught in the lake that year. Fish identified only to genus or higher taxonomic level are not included if any fish identified to species within that genus or higher taxonomic level are caught. E.g., Unidentified Chub would be only included in the richness value if no other chub is caught in that lake that year. Sampling Frequency: annually. Number of sites: 11
Note that 2020 data does not exist due to insufficient sampling. In 2021, sampling in Fish Lake was suspended due to significant lake level changes.
Core Areas
Dataset ID
245
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Sampling sites were chosen by random process in 1981 for the Northern lakes (Trout, Allequash, Sparkling, Crystal, and Big Muskellunge). Sites for Lake Mendota were chosen in 1981, and for the other Madison lakes (Monona, Fish, and Wingra) in 1995. All sites are identified with GPS coordinates, except on the bog lakes (Trout Bog and Crystal Bog) where nets are placed equal distances apart around the entire circumference of the lake in approximately the same locations each year.

Night seining is conducted on 6 seine sites per lake, each consisting of 100 meters of shoreline. Prior to 1997 this was subdivided into 3 seine hauls, each covering 33 meters. In 1997, seine hauls were reduced to 2 hauls of 33m each. The final section of the site is used as an alternate seine site in the event of difficulty in one of the first two hauls.
The seine used is 12.2 m long by 1.2 m deep, consisting of two 5.5 x 1.2 m wings surrounding a 1.2 x 1.2 x 1.2 m central bag. The wings are made of 6.4 mm stretch measure knitted delta-strength nylon mesh, and the bag is of 3.2 mm delta strength nylon mesh. The entire net is tarred. The two wings and the opening to the bag have weighted foot ropes and buoyed head ropes. An 8m length of rope is tied between the seine poles as a guide for the maximum spread of the seine.

A trammel net is set at two sites in each lake, and fished for approximately 24 hours at each site. The net is set on the bottom, along a line perpendicular to the shoreline and crossing the thermocline, with the shallow end at about 3m depth,. The trammel net used is 30.5 m long and 1.1 m deep. It consists of two outer nets of 170 mm square 32 kg test mesh multifilament nylon with an inner panel of 51 mm stretch mesh 9 kg test multifilament nylon. The three nets are connected at the leaded foot line and the buoyed head rope.

Fyke nets are deployed at six littoral sampling sites in each lake, and fished for approximately 24 hours. In Crystal Bog and Trout Bog lakes the fyke nets are suspended by placing floats on the hoops and frames to prevent the nets from sinking into the sediments. For the northern lakes, each fyke net is approximately 12 m long and consists of two rectangular steel frames 90 cm wide by 75 cm high and 4 steel hoops, all covered by 7 mm delta stretch mesh nylon netting. An 8 m long by 1.25 m deep leader net made of 7 mm delta stretch mesh nylon netting is attached to a center bar of the first rectangular frame (net mouth). The second rectangular frame has two 10 cm wide by 70 cm high openings, one on each side of the frame center bar. The four hoops follow the second frame. Throats 10 cm in diameter are located between the second and third hoops. The net ends in a bag with a 20.4 cm opening at the end, which is tied shut while the net is fishing. New nets of the same dimensions were purchased for the Northern Highland lakes in 2000. Fyke nets for the Madison lakes are 10 m long (including lead) with 1 rectangular aluminum frame followed by 2 aluminum hoops. The aluminum frame is 98 cm wide x 82 cm tall, and is constructed of 2.5 cm tubing, with an additional center vertical bar. The hoops are 60 cm in diameter and constructed of 5 mm diameter aluminum rod. The single net funnel is between the first and second hoops and is 20 cm in diameter. The lead is 8 m long and 1.25m deep, constructed from 7mm delta stretch mesh.

Crayfish traps are set on all lakes except the bog lakes (Crystal Bog and Trout Bog). Minnow traps are set only on the bog lakes. Prior to 1998, five traps were set at each fyke net site. Beginning 1998, three traps are set per site. Minnow traps and crayfish traps are set in shallow water (approx 1 m), 2 traps on one side, and 1 trap on the other side of the fyke net lead. Minnow traps are baited with 1 slice of bread, and crayfish traps with 120 g of beef liver. Traps are fished for approximately 24 hours. Crayfish are identified to species. Minnows caught in either crayfish or minnow traps are identified to species, and measured for total length. Minnow traps are galvanized steel two piece traps, 44.5 cm long by 30.5 cm maximum diameter with 2.5 cm diameter openings at the ends. The mesh size is 6.4 mm on a side. Crayfish traps are identical, but the opening hole of both sides of the trap has been forced to 5 to 7 cm. Crayfish sampling was terminated for the southern lakes in 2004 after it was determined that the catch per unit effort was too low (2 crayfish caught in 500+ traps)

Gill nets are set at the deepest point of all LTER lakes except Crystal Bog, Trout Bog, and Fish Lake. The nets are set for two consecutive 24 hour sets. The gill nets are a set of 7 nets, each in a different mesh size, hung vertically on foam rollers from the surface to the bottom of the lake, and chained together in a line. Each net is 4 m wide and 33 m long. From 1981 through 1990 the nets were multifilament mesh, in stretched mesh sizes of 19, 25, 32, 38, 51, 64, and 89 mm. In 1991, the multifilament nets were replaced with monofilament nets of the same sizes. Stretcher bars are installed at 10 meter intervals from the bottom to keep the net as rectangular as possible when deployed.

A boom style electrofishing system is used to sample the littoral zone fish community. Prior to 1997, four electrofishing transects were done on each lake. In 1997, the number of transects was reduced to 3. The same transects are used each year. Each transect consists of 30 minutes of current output, with the boat moving parallel to shore in 1-2 meters of water at a slow steady speed. We use the DC pulse system, with 240 volts at 3-5 amps. Transect lengths vary depending upon the size of the lake. If the end of a transect is reached before 30 minutes has elapsed, time is paused while the electrofisher loops back to the start of the transect. The transect is then repeated for the remaining time.

For all collecting methods, the fish are processed as follows. Each individual fish is identified to species. The total length of the fish is measured in mm, from nose to pinched tail. Prior to 1997, the weight of the first five fish of each species in each 10 mm size category was also measured, using Pesola spring balances. Starting in 1997, two fish are weighed for each species in each 5mm size category. A scale sample is collected from each yellow perch, rock bass, and cisco that is weighed. For gill net catches, the depth at which each individual is caught is also recorded.

Protocol Log. 1983: Discontinued fyke nets and trammel nets on Lake Mendota until 1995. 1984: Discontinued crayfish on Lake Mendota until 1995. Only gillnet and seines on Lake Mendota.1995: Resumed sampling Lake Mendota with the full suite of sampling gear. 1995: Began sampling Lakes Wingra, Monona, and Fish. 1997: Two fish are weighed for each fish species in each 5mm size category. Previously, five fish were weighed for each fish species in each 10mm size category. 1997: Data recording switched from manual field sheets to an electronic system. 1997: Changed from 4 to 3 electrofishing runs per lake. 1997: Changed from 18 to 12 seine hauls per lake. 1998: Changed from 30 to 18 crayfish or minnow traps per lake. 2004: Discontinued crayfish or minnow traps on southern lakes. 2020: Fish sampling very limited due to pandemic. 2021: Discontinued all night seining.
Short Name
NTLFI05
Version Number
25

North Temperate Lakes LTER: Benthic Macroinvertebrates 1981 - current

Abstract
Macroinvertebrates are collected from selected shoreline and deep water locations in the seven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, and unnamed lakes 27-02 [Crystal Bog], and 12-15 [Trout Bog]) in the Trout Lake area using modified Hester-Dendy samplers. Samplers are placed at fyke net and gill net locations in August and retrieved 3-4 weeks later. Macroinvertebrates are preserved in ethanol. This dataset contains counts of various groups of macroinvertebrates identified from specific samples. The majority of the identifications are at the genus level. The data table "Benthic Macroinvertebrate Codes" identifies the taxonomic group represented by each group code. Taxonomic references: Ecology and Classification of North American Freshwater Invertebrates, Edited by James H Thorp and Alan P Covich, Academic Press, Inc, 1991; Aquatic Insects of Wisconsin, William L Hilsenhoff, Natural History Museums Council, University of Wisconsin-Madison (1995). Sampling Frequency: annually Number of sites: 7
Core Areas
Dataset ID
11
Date Range
-
Maintenance
Sampling continues, however, sample analysis happens only during specific projects. Samples are maintained in the zoological museum and can be checked out.
Metadata Provider
Methods
The modified Hester-Dendy samplers are constructed as a bolted together stack of ten plastic mesh panels and a plastic scrubbing ball between hardboard end panels. They are placed in the lakes early to mid August, and left for approximately four weeks. Each sampling site consists of three dendy samplers spaced 3 meters apart. Shoreline samplers are set in about one meter of water, deep sites at the deepest part of the lake. The shoreline sets are retrieved by a snorkeler who places the sampler in a container before surfacing to avoid loss of invertebrates due to disturbance, while deep sites are pulled up to the surface from a boat. Samplers are preserved in ethanol in the field, disassembled in the lab, and the invertebrates identified and counted under a dissecting microscope. All invertebrates are preserved in ethanol and archived in the UW Zoology museum. Samplers were set in all seven lakes in 1981-1989,1992 and 1993. Only Trout, Sparkling, and Crystal Lakes were sampled in 1990, 1991, and 1994 to present. No lakes were sampled in 2020.
Publication Date
Short Name
NTLIB01
Version Number
35

North Temperate Lakes LTER: Fish Abundance 1981 - current

Abstract
This data set is a derived data set based on fish catch data. Data are collected annually to enable us to track the fish assemblages of eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, Trout, bog lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra and Fish). Sampling on Lakes Monona, Wingra, and Fish started in 1995; sampling on other lakes started in 1981. Sampling is done at six littoral zone sites per lake with seine, minnow or crayfish traps, and fyke nets; a boat-mounted electrofishing system samples three littoral transects. Vertically hung gill nets are used to obtain two pelagic samples per lake from the deepest point. A trammel net samples across the thermocline at two sites per lake. In the bog lakes only fyke nets and minnow traps are deployed. Parameters measured include species-level identification and lengths for all fish caught, and weight and scale samples from a subset. Derived data sets include species richness, catch per unit effort, and size distribution by species, lake, and year. Protocol used to generate data: Day seines were only used in 1981 and have been eliminated from this data set to make sampling effort across years comparable. Number caught for each species is summed over repetitions of a gear within a lake and over depth. For information on fish stocking by the Wisconsin Department of Natural Resources in LTER lakes in Dane and Vilas counties, see https://dnr.wi.gov/fisheriesmanagement/Public/Summary/Index The only sampling done in 2020 were a single gill-netting replicate in Sparkling, Crystal, and Trout lakes. Sampling in Fish Lake was suspended in 2021 due to significant lake level changes. Sampling Frequency: annually. Number of sites: 11
Core Areas
Dataset ID
7
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Sampling sites were chosen by random process in 1981 for the Northern lakes (Trout, Allequash, Sparkling, Crystal, and Big Muskellunge). Sites for Lake Mendota were chosen in 1981, and for the other Madison lakes (Monona, Fish, and Wingra) in 1995. All sites are identified with GPS coordinates, except on the bog lakes (Trout Bog and Crystal Bog) where nets are placed equal distances apart around the entire circumference of the lake in approximately the same locations each year.

Night seining is conducted on 6 seine sites per lake, each consisting of 100 meters of shoreline. Prior to 1997 this was subdivided into 3 seine hauls, each covering 33 meters. In 1997, seine hauls were reduced to 2 hauls of 33m each. The final section of the site is used as an alternate seine site in the event of difficulty in one of the first two hauls.
The seine used is 12.2 m long by 1.2 m deep, consisting of two 5.5 x 1.2 m wings surrounding a 1.2 x 1.2 x 1.2 m central bag. The wings are made of 6.4 mm stretch measure knitted delta-strength nylon mesh, and the bag is of 3.2 mm delta strength nylon mesh. The entire net is tarred. The two wings and the opening to the bag have weighted foot ropes and buoyed head ropes. An 8m length of rope is tied between the seine poles as a guide for the maximum spread of the seine.

A trammel net is set at two sites in each lake, and fished for approximately 24 hours at each site. The net is set on the bottom, along a line perpendicular to the shoreline and crossing the thermocline, with the shallow end at about 3m depth,. The trammel net used is 30.5 m long and 1.1 m deep. It consists of two outer nets of 170 mm square 32 kg test mesh multifilament nylon with an inner panel of 51 mm stretch mesh 9 kg test multifilament nylon. The three nets are connected at the leaded foot line and the buoyed head rope.

Fyke nets are deployed at six littoral sampling sites in each lake, and fished for approximately 24 hours. In Crystal Bog and Trout Bog lakes the fyke nets are suspended by placing floats on the hoops and frames to prevent the nets from sinking into the sediments. For the northern lakes, each fyke net is approximately 12 m long and consists of two rectangular steel frames 90 cm wide by 75 cm high and 4 steel hoops, all covered by 7 mm delta stretch mesh nylon netting. An 8 m long by 1.25 m deep leader net made of 7 mm delta stretch mesh nylon netting is attached to a center bar of the first rectangular frame (net mouth). The second rectangular frame has two 10 cm wide by 70 cm high openings, one on each side of the frame center bar. The four hoops follow the second frame. Throats 10 cm in diameter are located between the second and third hoops. The net ends in a bag with a 20.4 cm opening at the end, which is tied shut while the net is fishing. New nets of the same dimensions were purchased for the Northern Highland lakes in 2000. Fyke nets for the Madison lakes are 10 m long (including lead) with 1 rectangular aluminum frame followed by 2 aluminum hoops. The aluminum frame is 98 cm wide x 82 cm tall, and is constructed of 2.5 cm tubing, with an additional center vertical bar. The hoops are 60 cm in diameter and constructed of 5 mm diameter aluminum rod. The single net funnel is between the first and second hoops and is 20 cm in diameter. The lead is 8 m long and 1.25m deep, constructed from 7mm delta stretch mesh.

Crayfish traps are set on all lakes except the bog lakes (Crystal Bog and Trout Bog). Minnow traps are set only on the bog lakes. Prior to 1998, five traps were set at each fyke net site. Beginning 1998, three traps are set per site. Minnow traps and crayfish traps are set in shallow water (approx 1 m), 2 traps on one side, and 1 trap on the other side of the fyke net lead. Minnow traps are baited with 1 slice of bread, and crayfish traps with 120 g of beef liver. Traps are fished for approximately 24 hours. Crayfish are identified to species. Minnows caught in either crayfish or minnow traps are identified to species, and measured for total length. Minnow traps are galvanized steel two piece traps, 44.5 cm long by 30.5 cm maximum diameter with 2.5 cm diameter openings at the ends. The mesh size is 6.4 mm on a side. Crayfish traps are identical, but the opening hole of both sides of the trap has been forced to 5 to 7 cm. Crayfish sampling was terminated for the southern lakes in 2004 after it was determined that the catch per unit effort was too low (2 crayfish caught in 500+ traps)

Gill nets are set at the deepest point of all LTER lakes except Crystal Bog, Trout Bog, and Fish Lake. The nets are set for two consecutive 24 hour sets. The gill nets are a set of 7 nets, each in a different mesh size, hung vertically on foam rollers from the surface to the bottom of the lake, and chained together in a line. Each net is 4 m wide and 33 m long. From 1981 through 1990 the nets were multifilament mesh, in stretched mesh sizes of 19, 25, 32, 38, 51, 64, and 89 mm. In 1991, the multifilament nets were replaced with monofilament nets of the same sizes. Stretcher bars are installed at 10 meter intervals from the bottom to keep the net as rectangular as possible when deployed.

A boom style electrofishing system is used to sample the littoral zone fish community. Prior to 1997, four electrofishing transects were done on each lake. In 1997, the number of transects was reduced to 3. The same transects are used each year. Each transect consists of 30 minutes of current output, with the boat moving parallel to shore in 1-2 meters of water at a slow steady speed. We use the DC pulse system, with 240 volts at 3-5 amps. Transect lengths vary depending upon the size of the lake. If the end of a transect is reached before 30 minutes has elapsed, time is paused while the electrofisher loops back to the start of the transect. The transect is then repeated for the remaining time.

For all collecting methods, the fish are processed as follows. Each individual fish is identified to species. The total length of the fish is measured in mm, from nose to pinched tail. Prior to 1997, the weight of the first five fish of each species in each 10 mm size category was also measured, using Pesola spring balances. Starting in 1997, two fish are weighed for each species in each 5mm size category. A scale sample is collected from each yellow perch, rock bass, and cisco that is weighed. For gill net catches, the depth at which each individual is caught is also recorded.

Protocol Log. 1983: Discontinued fyke nets and trammel nets on Lake Mendota until 1995. 1984: Discontinued crayfish on Lake Mendota until 1995. Only gillnet and seines on Lake Mendota.1995: Resumed sampling Lake Mendota with the full suite of sampling gear. 1995: Began sampling Lakes Wingra, Monona, and Fish. 1997: Two fish are weighed for each fish species in each 5mm size category. Previously, five fish were weighed for each fish species in each 10mm size category. 1997: Data recording switched from manual field sheets to an electronic system. 1997: Changed from 4 to 3 electrofishing runs per lake. 1997: Changed from 18 to 12 seine hauls per lake. 1998: Changed from 30 to 18 crayfish or minnow traps per lake. 2004: Discontinued crayfish or minnow traps on southern lakes. 2020: Fish sampling very limited due to pandemic. 2021 discontinued all night seining.

DATA MODIFICATIONS
Prior to 2018, gill net data had been standardized to a 24-hour sampling period. This is no longer the case, and catch numbers for all years have been recomputed to reflect the number of fish actually caught.
2018-01-18: Species names ('spname') added in 2012 had space characters appended to the end of the name. These spaces have been removed. The occasional appearance throughout the data set of species name 'SUNFISH' and 'LARVALSUNFISH' have all been changed to 'UNIDSUNFISH'.
Short Name
NTLFI02
Version Number
41

Landscape Position Project at North Temperate Lakes LTER: Aquatic Macrophytesn 1998 - 1999

Abstract
Submersed and floating macrophytes were surveyed along transects running perpendicular to shore at two sites representative of muck (organic) and sand substrate macrophyte communities. Data were collected by Karen A. Wilson as part of her PhD work in Northern Wisconsin, (Vilas and Onieda Counties) during July and August of 1998 and 1999. Details of field collections can be found in Wilson, K.A. 2002. Impacts of the invasive rusty crayfish (Orconectes rusticus) in northern Wisconsin lakes. Ph.D. Dissertation. University of Wisconsin, Madison. Number of sites: 30 lakes; 2 sites per lake
Core Areas
Creator
Dataset ID
109
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Details of field collections can be found in Wilson, K.A. 2002. Impacts of the invasive rusty crayfish (Orconectes rusticus) in northern Wisconsin lakes. Ph.D. Dissertation. University of Wisconsin, Madison.
Short Name
LPPMACR
Version Number
7
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