US Long-Term Ecological Research Network

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: 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
31

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
32

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 four 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 idenitified 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.
Core Areas
Dataset ID
245
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
SAMPLING SITES The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Lakes are sampled in the following order: Trout, Allequash, Crystal, Big Muskellunge, Sparkling, Crystal Bog, Trout Bog, Wingra, Fish, Monona, Mendota. Sites for fyke nets, trammel nets and night seining sites were chosen by random process in 1981 for the Northern Highland State Forest lakes (Trout, Big Muskellunge, Allequash, Crystal, Sparkling). Sites for Lake Mendota were chosen in 1981, and for the other Madison lakes (Monona, Fish, and Wingra) in 1995. In 1998, all the Northern Highland lake sampling sites were recorded and archived as GPS coordinates. In 1999, all the Madison lake sites were recorded and archived as GPS sites. Prior to 1998 and 1999, fyke and trammel net sites were found each year by reference to lake maps, local landmarks, and stake locations. Gill nets are placed near the deep-hole, which is marked by a buoy and GPS coordinates, on each lake. In the bog lakes (Trout Bog and Crystal Bog), which are sampled with only fyke nets and minnow traps, there are no fixed sites; nets are placed equal distances apart around the entire circumference of the lake in approximately the same locations each year. NIGHT SEINING Night seining is conducted to achieve relative abundances of small fish species such as minnows, darters, sculpin, and young gamefish species on a yearly basis. Seining is most effective on small fish at night, due to reduced net avoidance, and is one of the most effective methods of catching small fish species. 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. The seine is pulled via two PVC or steel poles on either end of the seine. Prior to 1997, seine sites consisted of 100 meters of shoreline. This was subdivided into 3 seine hauls, each covering 33 meters. Stakes were placed to mark the beginning and end of each haul, with the first stake lettered A and the fourth (final) stake lettered D. In 1997, seine hauls were reduced to 2 hauls of 33m each. The final 34m of the 100m site (stakes C-D) is now used as an alternate seine site in the event of difficulty (snag, twisted net) in one of the first two hauls. Our convention is that the first haul (identified as "site number -1") is the one segment at the left end of the site, as one faces the site from the lake. The day crew working the lake will have marked the location of these stakes using green 12-hour chemical light sticks. There are 6 seine sites per lake for a total of 18 hauls per lake prior to 1997; starting in 1997, there are 12 hauls per lake. The seine crew approaches the site from the lake by boat in such a way as not to pass over the area to be seined. The seine is deployed using as little light as possible. An 8m length of rope is tied between the poles as a guide for the maximum spread of the seine. Two people, working 8 meters apart when possible, pull the seine on a course parallel to the shore line. The outside or deep person should be 8m from the shallow person (max rope length) or as deep as they can be without overtopping their waders (just below chest height). The inside or shallow person keeps as close to shore as possible without steeping onto dry land. When the shallow person is about 8 meters from the end of the haul heorshe moves very slowly, allowing the deep person to swing around toward the chemical light stick; both seiners should reach the light at the same time. The seine is quickly landed by crossing the poles and drawing the lead line together. The lead line is kept on the lake bottom while the wings are drawn in. When the bag reaches the poles it is picked up by the 4 corners. Fish are collected from the bag and processed before the crew goes on to the next haul. TRAMMEL NET The trammel net is used to sample fish species present near the bottom at the thermoclineorsubstrate interface. This area is utilized by a number of fish species, and is an important area of the lake due to the large change in temperature in a relatively short distance. As in the terrestrial environment, the thermocline acts as an ecotone and several fish species which require very different physical environments may exist in relatively close proximity. So achieving yearly fish abundances in this habitat is also important in determining long term trends in fish abundances. 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. The trammel net is set on the bottom, along a line perpendicular to the shoreline and crossing the thermocline. This can generally be accomplished by setting the shallow end in about 3 meters of water, and running the net out perpendicular to shore. Fish are picked out of the trammel net as it is brought back into the boat. The trammel net is set by the day crew at two sites in each lake, and fished for approximately 24 hours at each site. FYKE NETS Fyke netting is a very common method of sampling a wide size range of fishes which use littoral zone habitat. At different times of the day andoror season, many different fish species utilize the littoral zone area for feeding, digesting, and mating purposes. Sampling the abundances of fish species in this area, thus, is also very important in determining yearly changes in fish abundances. To monitor yearly changes in littoral fish abundances, fyke nets are deployed at six sampling sites in all 11 LTER study lakes. A separate set of three fyke nets of similar dimensions are used for the Northern Highland lakes and the Madison lakes. For the Northern Higland 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 s 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 has the dimensions 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. Each fyke net is set in shallow water perpendicular to shore such that the net mouth is covered by about 1 meter of water when possible. When the net is properly set, the lead is perpendicular to shore, vertical and not twisted, the mouth of the net is upright and facing shore, and all the hoops are upright. When the net is pulled in, the hoops and frames are gathered together and lifted into the boat. The net is positioned over a live well with the net mouth upward. One frame at a time is lifted and any fish present are shaken down into the next chamber, until all the fish are in the bag, which is emptied into the live well. Three fyke net sites are set per day (for two days), each with a single net in the middle of a 100m site, for a total of 6 fyke net sites per lake. Due to the soft bottom, and small size of the bog lakes, minnow traps and fyke nets are the only gear used to sample the fish community of these systems. The fyke nets are suspended by placing floats at the apex of each hoop, and on the top of the opening frames. This is done to prevent the nets from sinking into the soft sediments at the bottom of the bogs. CRAYFISH AND MINNOW TRAPS There have been introductions of exotic crayfish species in recent years into many north temperate lakes. Monitoring yearly abundances of crayfish species is important in determining the status and extent of the invasions. 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. Starting in 1998, three traps are set per site. Thus, prior to 1998, thirty traps were set on each lake (covering 6 sites.) As of 1998, 18 traps are set on each lake. 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 per trap to attract minnows inhabiting the bogs. Crayfish traps are baited with 120 g of liver. Traps are fished for approximately 24 hours . Crayfish are identified to species and returned to the lake. Minnows caught in either the crayfish or minnow traps are identified to species, measured for total length. Minnow traps used 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. GILL NETS In most lakes, there are species of fish which inhabit the pelagic (open water) zone. These fish species can have a large impact on lake ecosystem dynamics when they occur in abundance. To monitor yearly changes in the abundance of pelagic fish species, we sample the deep basin of eight of the LTER lakes with vertical gill nets. Our gill nets are a set of 7 nets, each in a different mesh size, hung vertically from foam rollers, 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. One side of the net is marked in meters from top to bottom. Stretcher bars have been installed at 5 meter intervals from the bottom to keep the net as rectangular as possible when deployed. The bottom end is weighted with a lead pipe to quicken the placement of the net and to maintain the position of the net on the bottom. 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 nets are set in a straight line, each connected to the next, and anchored at each end of the line. Once the nets are in position, they are unrolled until the bottom end reaches the bottom, and then tied off to prevent further unrolling. The nets are pulled by placing each net onto a pair of brackets attached to the side of the boat and rolling the net back onto its float; the fish are picked out as the net is brought up, placed in tubs according to depth. The fish are processed when the net is completely rolled up and before it is redeployed. ELECTROFISHING We use a boom style electrofishing system 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. Two crew members in the bow of the boat dip up all stunned fish, placing them in the live well for processing at the end of each transect. Transect lengths vary depending upon the size of the lake. If the end of a transect is reached before 30 minutes has elpased, time is paused while the electrofisher loops back to the start of the transect. The transect is then repeated for the remaining time. In 1999, dip nets were standardized to 10 foot poles attached to 18in. x 20in. tear drop shaped hoops. The nets are made of 7 mm stretch mesh. PROCESSING THE CATCH For all collecting methods, the fish are processed as follows. Each individual fish is identified to species. If it cannot be positively identified, after it is processed, it is preserved in 10percent buffered formalin or 95percent ethanol for later identification. The total length of the fish (measured from nose to end of caudal fins pinched together) is measured in mm. Prior to 1997, the weight (g) of the first 5 fish of each species in each 10 mm size category was also measured, using the appropriate Pesola spring balance (fish weight registering in the middle range of scale). A tally sheet was used to record how many fish in each size category had been measured. Starting in 1997, 2 fish are weighed for each fish species in each 5mm size category. Also in 1997, data recording switched to an electronic system which tallied measured fish. For yellow perch, rock bass, and cisco, a scale sample is collected from each weighed fish. This is removed from the left side of the fish, above the lateral line and below the origin of the dorsal fin. Scale samples are stored in scale envelopes and labeled with a unique ID number, the date the scale was taken, a lake ID number, the species code, land length and weight. For gill net catches, the depth at which each individual is caught is also recorded. Fish from all gear (except gillnets) are held in live wells during processing. Fish are sorted by species into buckets, processed as quickly as possible, and returned to the lake. Fish from the gillnets are very rarely alive. If alive, they are usually badly damaged when the nets are raised. PROTOCOL CHANGES 1983 Discontinued fykenets 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 full suite of sampling gearr 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</p>
Short Name
NTLFI05
Version Number
24

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. Dominant species vary from lake to lake. Perch, rockbass, and bluegill are common, with walleye, large and smallmouth bass, northern pike and muskellunge as major piscivores. Cisco have been present in the pelagic waters of four lakes, and the exotic species, rainbow smelt, is present in two. The bog lakes contain mudminnows. 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. The absence of a species in a given lake/year indicates none were caught and the catch per unit effort is zero. For information on fish stocking by Wisconsin Department of Natural Resouces in LTER lakes in Dane and Vilas counties, see http://infotrek.er.usgs.gov/doc/wdnr_biology/Public_Stocking/StateMapHotspotsAllYears.htm.
The only sampling done in 2020 were a single gill-netting replicate in Sparkling, Crystal, and Trout lakes.
Sampling Frequency: annually. Number of sites: 11.
Core Areas
Dataset ID
7
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
SAMPLING SITES The same sampling sites are used each year. All sampling occurs between the 3rd week of July and Labor Day. Lakes are generally sampled in the following order: Allequash, Crystal, Big Muskellunge, Sparkling, Crystal Bog, Trout Bog, Trout, Wingra, Fish, Monona, Mendota. Sites for fyke nets, trammel nets and night seining sites were chosen by random process in 1981 for the Northern Highland State Forest lakes (Trout, Big Muskellunge, Allequash, Crystal, Sparkling). Sites for Lake Mendota were chosen in 1981, and for the other Madison lakes (Monona, Fish, and Wingra) in 1995. In 1998, all the Northern Highland lake sampling sites were recorded and archived as GPS coordinates. In 1999, all the Madison lake sites were recorded and archived as GPS sites. Prior to 1998 and 1999, fyke and trammel net sites were found each year by reference to lake maps, local landmarks, and stake locations. Gill nets are placed near the deep-hole, which is marked by a buoy (on most lakes) and/or GPS coordinates. In the bog lakes (Trout Bog and Crystal Bog), which are sampled with only fyke nets and minnow traps, there are no fixed sites; nets are placed equal distances apart around the entire circumference of the lake in approximately the same locations each year. NIGHT SEINING Night seining is conducted to achieve relative abundances of small fish species such as minnows, darters, sculpin, and young gamefish species on a yearly basis. Seining is most effective on small fish at night, due to reduced net avoidance, and is one of the most effective methods of catching small fish species. 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. The seine is pulled via two PVC or steel poles on either end of the seine. Prior to 1997, seine sites consisted of 100 meters of shoreline. This was subdivided into 3 seine hauls, each covering 33 meters. Stakes were placed to mark the beginning and end of each haul, with the first stake lettered A and the fourth (final) stake lettered D. In 1997, seine hauls were reduced to 2 hauls of 33m each. The final 34m of the 100m site (stakes C-D) is now used as an alternate seine site in the event of difficulty (snag, twisted net) in one of the first two hauls. Our convention is that the first haul (identified as "site number -1") is the one segment at the left end of the site, as one faces the site from the lake. The day crew working the lake will have marked the location of these stakes using green 12-hour chemical light sticks. There are 6 seine sites per lake for a total of 18 hauls per lake prior to 1997; starting in 1997, there are 12 hauls per lake. The seine crew approaches the site from the lake by boat in such a way as not to pass over the area to be seined. The seine is deployed using as little light as possible. An 8m length of rope is tied between the poles as a guide for the maximum spread of the seine. Two people, working 8 meters apart when possible, pull the seine on a course parallel to the shore line. The outside or deep person should be 8m from the shallow person (max rope length) or as deep as they can be without overtopping their waders (just below chest height). The inside or shallow person keeps as close to shore as possible without steeping onto dry land. When the shallow person is about 8 meters from the end of the haul heorshe moves very slowly, allowing the deep person to swing around toward the chemical light stick; both seiners should reach the light at the same time. The seine is quickly landed by crossing the poles and drawing the lead line together. The lead line is kept on the lake bottom while the wings are drawn in. When the bag reaches the poles it is picked up by the 4 corners. Fish are collected from the bag and processed before the crew goes on to the next haul. TRAMMEL NET The trammel net is used to sample fish species present near the bottom at the thermoclineorsubstrate interface. This area is utilized by a number of fish species, and is an important area of the lake due to the large change in temperature in a relatively short distance. As in the terrestrial environment, the thermocline acts as an ecotone and several fish species which require very different physical environments may exist in relatively close proximity. So achieving yearly fish abundances in this habitat is also important in determining long term trends in fish abundances. 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. The trammel net is set on the bottom, along a line perpendicular to the shoreline and crossing the thermocline. This can generally be accomplished by setting the shallow end in about 3 meters of water, and running the net out perpendicular to shore. Fish are picked out of the trammel net as it is brought back into the boat. The trammel net is set by the day crew at two sites in each lake, and fished for approximately 24 hours at each site. FYKE NETS Fyke netting is a very common method of sampling a wide size range of fishes which use littoral zone habitat. At different times of the day andoror season, many different fish species utilize the littoral zone area for feeding, digesting, and mating purposes. Sampling the abundances of fish species in this area, thus, is also very important in determining yearly changes in fish abundances. To monitor yearly changes in littoral fish abundances, fyke nets are deployed at six sampling sites in all 11 LTER study lakes. A separate set of three fyke nets of similar dimensions are used for the Northern Highland lakes and the Madison lakes. For the Northern Higland 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 s 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 has the dimensions 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. Each fyke net is set in shallow water perpendicular to shore such that the net mouth is covered by about 1 meter of water when possible. When the net is properly set, the lead is perpendicular to shore, vertical and not twisted, the mouth of the net is upright and facing shore, and all the hoops are upright. When the net is pulled in, the hoops and frames are gathered together and lifted into the boat. The net is positioned over a live well with the net mouth upward. One frame at a time is lifted and any fish present are shaken down into the next chamber, until all the fish are in the bag, which is emptied into the live well. Three fyke net sites are set per day (for two days), each with a single net in the middle of a 100m site, for a total of 6 fyke net sites per lake. Due to the soft bottom, and small size of the bog lakes, minnow traps and fyke nets are the only gear used to sample the fish community of these systems. The fyke nets are suspended by placing floats at the apex of each hoop, and on the top of the opening frames. This is done to prevent the nets from sinking into the soft sediments at the bottom of the bogs. CRAYFISH AND MINNOW TRAPS There have been introductions of exotic crayfish species in recent years into many north temperate lakes. Monitoring yearly abundances of crayfish species is important in determining the status and extent of the invasions. 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. Starting in 1998, three traps are set per site. Thus, prior to 1998, thirty traps were set on each lake (covering 6 sites.) As of 1998, 18 traps are set on each lake. 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 per trap to attract minnows inhabiting the bogs. Crayfish traps are baited with 120 g of liver. Traps are fished for approximately 24 hours . Crayfish are identified to species and returned to the lake. Minnows caught in either the crayfish or minnow traps are identified to species, measured for total length. Minnow traps used 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. GILL NETS In most lakes, there are species of fish which inhabit the pelagic (open water) zone. These fish species can have a large impact on lake ecosystem dynamics when they occur in abundance. To monitor yearly changes in the abundance of pelagic fish species, we sample the deep basin of eight of the LTER lakes with vertical gill nets. Our gill nets are a set of 7 nets, each in a different mesh size, hung vertically from foam rollers, 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. One side of the net is marked in meters from top to bottom. Stretcher bars have been installed at 10 meter intervals from the bottom to keep the net as rectangular as possible when deployed. The bottom end is weighted with a lead pipe to quicken the placement of the net and to maintain the position of the net on the bottom. 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 nets are set in a straight line, each connected to the next, and anchored at each end of the line. Once the nets are in position, they are unrolled until the bottom end reaches the bottom, and then tied off to prevent further unrolling. The nets are pulled by placing each net onto a pair of brackets attached to the side of the boat and rolling the net back onto its float; the fish are picked out as the net is brought up, placed in tubs according to depth. The fish are processed when the net is completely rolled up and before it is redeployed. ELECTROFISHING We use a boom style electrofishing system 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. Two crew members in the bow of the boat dip up all stunned fish, placing them in the live well for processing at the end of each transect. Transect lengths vary depending upon the size of the lake. If the end of a transect is reached before 30 minutes has elpased, time is paused while the electrofisher loops back to the start of the transect. The transect is then repeated for the remaining time. In 1999, dip nets were standardized to 10 foot poles attached to 18in. x 20in. tear drop shaped hoops. The nets are made of 7 mm stretch mesh. PROCESSING THE CATCH For all collecting methods, the fish are processed as follows. Each individual fish is identified to species. If it cannot be positively identified, after it is processed, it is preserved in 10percent buffered formalin or 95percent ethanol for later identification. The total length of the fish (measured from nose to end of caudal fins pinched together) is measured in mm. Prior to 1997, the weight (g) of the first 5 fish of each species in each 10 mm size category was also measured, using the appropriate Pesola spring balance (fish weight registering in the middle range of scale). A tally sheet was used to record how many fish in each size category had been measured. Starting in 1997, 2 fish are weighed for each fish species in each 5mm size category. Also in 1997, data recording switched to an electronic system which tallied measured fish. For yellow perch, rock bass, and cisco, a scale sample is collected from each weighed fish. This is removed from the left side of the fish, above the lateral line and below the origin of the dorsal fin. Scale samples are stored in scale envelopes and labeled with a unique ID number, the date the scale was taken, a lake ID number, the species code, land length and weight. For gill net catches, the depth at which each individual is caught is also recorded. Fish from all gear (except gillnets) are held in live wells during processing. Fish are sorted by species into buckets, processed as quickly as possible, and returned to the lake. Fish from the gillnets are very rarely alive. If alive, they are usually badly damaged when the nets are raised. PROTOCOL CHANGES</p>1995 Resumed sampling Lake Mendota with 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 2015 The sampling lake order was changed for the northern lakes. Trout Lake, which was formerly sampled first, is now last due to the presence of spiny water flea. 2016 The sampling lake order was changed for the southern lakes. Fish Lake is sampled first and Mendota last to avoid bringing invasive species to Fish Lake. Winga had generally been the first since 1995.</p>DATA MODIFICATIONS</p>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.</p>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'.</p>&nbsp;</p>
Short Name
NTLFI02
Version Number
40

Landscape Position Project at North Temperate Lakes LTER: Benthic Invertebrate Abundance 1998 - 1999

Abstract
Benthic invertebrate assemblages of 32 lakes were surveyed as part of the Landscape Position Project. We used modified Hester-Dendy colonization substrates to sample benthic invertebrate communities. Each sampling device consisted of a 3&quot;x3&quot; top plate, alternating layers of course and fine mesh, a &#39;&#39;choreboy&#39;&#39; commercial scrubbing puff, alternating layers of coarse (6.35 mm) and fine (3.18 mm) black plastic mesh, and a 3&quot;x3&quot; bottom plate. Two Hester-Dendy samplers were set at a depth of one meter on each of three substrate types (cobble, sand and silt) within each lake for four weeks in late June through late July in either 1998 or 1999. Within each lake, areas of different substrate types were identified using WI-DNR depth contour lake maps, and substrate type was verified by direct observation. Different substrates were sampled to account for invertebrate associations with specific substrate characteristics. Lake order was determined using a modification of the method of Riera et al. (2000). Lake order is a numerical surrogate for groundwater influx and hydrological position along a drainage network, with the highest number indicating the lake lowest in a watershed. Riera, Joan L., John J. Magnuson, Tim K. Kratz, and Katherine E. Webster. 2000. A geomorphic template for the analysis of lake districts applied to Northern Highland Lake District, Wisconsin, U.S.A. Freshwater Biology 43:301-18. Sampling Frequency: one survey on each lake in late June through late July of 1998 or 1999 Number of sites: 32
Core Areas
Dataset ID
96
Date Range
-
Maintenance
completed
Metadata Provider
Methods
We used modified Hester-Dendy colonization substrates to sample benthic invertebrate communities. Each sampling device consisted of a 3&quot;x3&quot; top plate, alternating layers of course and fine mesh, a choreboy commercial scrubbing puff, alternating layers of coarse (6.35 mm) and fine (3.18 mm) black plastic mesh, and a 3&quot;x3&quot; bottom plate. Two Hester-Dendy samplers were set at a depth of one meter on each of three substrate types (cobble, sand and silt) within each lake for four weeks in late June through late July in either 1998 or 1999. Within each lake, areas of different substrate types were identified using WI-DNR depth contour lake maps, and substrate type was verified by direct observation. Different substrates were sampled to account for invertebrate associations with specific substrate characteristics. Lake order was determined using a modification of the method of Riera et al. (2000). Lake order is a numerical surrogate for groundwater influx and hydrological position along a drainage network, with the highest number indicating the lake lowest in a watershed. Riera, Joan L., John J. Magnuson, Tim K. Kratz, and Katherine E. Webster. 2000. A geomorphic template for the analysis of lake districts applied to Northern Highland Lake District, Wisconsin, U.S.A. Freshwater Biology 43:301-18. Sampling Frequency: one survey on each lake in late June through late July of 1998 or 1999 Number of sites: 32
Short Name
LPPINVA1
Version Number
6

Lake Wingra: Fish Abundance

Abstract
Data are collected annually to enable us to track the fish assemblages of Lake Wingra. Sampling is done at six littoral zone sites per lake with a beach seine, minnow or crayfish traps, and fyke nets, while a boat-mounted electrofishing system samples four 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 nearshore sites per lake. Fish are identified to species. Lengths are measured for all fish caught, while weight and scale are collected from a subset. Derived data include catch per unit effort and size distribution by species, lake, and year. Protocol used to generate data: Gill net data have been standardized to a 24-hour sampling period. Assumptions used in the standardization are available from the investigators. Number caught for each species is summed over repetitions of a gear within a lake and over depth Sampling Frequency: annually. Number of sites: 1. Note that 2020 data does not exist due to insufficient sampling.
Core Areas
Dataset ID
182
Date Range
-
Maintenance
ongoing
Metadata Provider
Short Name
FOLWFI02
Version Number
18

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.&mdash;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.&mdash;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.&mdash;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
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