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
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: 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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