US Long-Term Ecological Research Network

Changing Lake Variables

The overarching theme of this research is to determine how lake variables (e.g. ice cover, thermal structure, water level) have changed during the past century, and how they may continue to change under a changing climate. Currently, I am focusing on one dimensional and three dimensional hydrodynamic modeling of the NTL-LTER study lakes. Development of hydrodynamic models allows for understanding of lake dynamics that cannot be captured by field measurements, and also provides the ability to predict how changes in external ...

North Temperate Lakes LTER: Physical Limnology of Primary Study Lakes 1981 - current

Abstract
Parameters characterizing the physical limnology of the 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) are measured at one station in the deepest part of each lake at 0.25-m to 1-m depth intervals depending on the lake. Measured parameters in the data set include water temperature, vertical penetration of photosynthetically active radiation (PAR; not measured on lakes Mendota, Monona, Wingra, and Fish), dissolved oxygen, as well as the derived parameter percent oxygen saturation. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season for the northern lakes. The southern lakes are similar except that sampling occurs monthly during the fall and typically only once during the winter (depending on ice conditions). Number of sites: 11
Core Areas
Dataset ID
29
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
Light (PAR) extinction coefficient is calculated by linearly regressing ln (FRLIGHT (z)) on depth z where the intercept is not constrained. FRLIGHT(z) = LIGHT(z) or DECK(z) where LIGHT(z) is light measured at depth z and DECK(z) is light measured on deck (above water) at the same time. For open water light profiles, the surface light measurement (depth z = 0) is excluded from the regression. For winter light profiles taken beneath the ice, the first light data are taken at the bottom of the ice cover and are included in the regression. The depth of uppermost light value is equal to the depth of the ice adjusted by the water level in the sample hole, i.e., the depth below the surface of the water. The water level can be at, above or below the surface of the ice. If the water level was not recorded, it is assumed to be 0.0 and the calculated light extinction coefficient is flagged. If ice thickness was not recorded, a light extinction coefficient is not calculated. For light data collected prior to March, 2007, light values less than 3.0 (micromolesPerMeterSquaredPerSec) are excluded. For light data collected starting in March 2007, light values less than 1.0 (micromolesPerMeterSquaredPerSec) are excluded. Except for bog lakes before August 1989, a light extinction coefficient is not calculated if there are less than three FRLIGHT values to be regressed. For bog lakes before August 1989, a light extinction coefficient is calculated if there are least two FRLIGHT values to be regressed. In these cases, the light extinction coefficient is flagged as non-standard. FRLIGHT values should be monotonically decreasing with depth. For light profiles where this is not true, a light extinction coefficient is not calculated. For samples for which light data at depth are present, but the corresponding deck light are missing, a light extinction coefficient is calculated by regressing ln (LIGHT (z)) on depth z. Note that if actual deck light had remained constant during the recording of the light profile, the resulting light extinction coefficient is the same as from regressing ln(FRLIGHT(z)). In these cases, the light extinction coefficient is flagged as non-standard. Oxygen and Temperature: We sample at the deepest part of the lake, taking a temperature and oxygen profile at meter intervals from the surface to within 1 meter of the bottom using a YSI Pro-ODO temporDO meter. We sample biweekly during open water and approximately every five weeks during ice cover. Protocol Log: Prior to 2011, we used a YSI Model 58 temporDO meter.
Short Name
NTLPH01
Version Number
27

North Temperate Lakes LTER: High Frequency Water Temperature Data - Sparkling Lake Raft 1989 - current

Abstract
The instrumented raft on Sparkling Lake is equipped with a thermistor chain that measures water temperature from depths ranging from the surface to 18m at intervals from 0.5 to 3m throughout the water column. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. The raft on Sparkling Lake is also equipped with a dissolved oxygen sensor and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, evaporation rates, and lake metabolism. Estimating the flux of solutes to and from lakes requires accurate water budgets. Evaporation rates are a critical component of the water budget of lakes. Data from the instrumented raft on Sparkling Lake includes micrometeorological parameters from which evaporation can be calculated. Raft measurements of relative humidity and air temperature (2 m height), wind velocity (1, 2, and 3 m heights), and water temperatures are combined with measurements of total long-wave and short-wave radiation data from a nearby shore station to determine evaporation by the energy budget technique. Comparable evaporation estimates from mass transfer techniques are calibrated against energy budget estimates to produce a lake-specific mass transfer coefficient for use in estimating evaporation rates Sampling Frequency: one minute; averaged to hourly and daily values as well as higher resolution values such as 2 min and 10 min. Number of sites: 1
Dataset ID
5
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
see abstract for methods description
Short Name
NTLEV02
Version Number
22

North Temperate Lakes LTER: High Frequency Water Temperature Data - Sparkling Bog North Buoy 2008 - current

Abstract
The instrumented buoy on Sparkling Bog North is equipped with a thermistor chain that measures water temperature at the surface, at 0.25 m and at every .5 m from 0.5 m to 4.5 m. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. The buoy is also equipped with a dissolved oxygen sensor, meteorological sensors, a CO2 sensor and a YSI AutoProfiler that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Prior to May 2009, data were collected at 1 minute or 10 minute intervals. Since May 2009, data are being collected each minute. Hourly and daily water temperature averages are computed from high resolution data. Hourly and daily values may not be current with high resolution data. In 2008, the instrumented buoy was deployed in Sparkling Bog North from March 24 to November 10. In 2009, the buoy was deployed on the ice on March 7 and was not removed for the winter of 2009 to 2010. Sampling Frequency: varies for instantaneous sample. Generally 1 minute or 10 minutes. Number of sites: 1
Dataset ID
228
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented buoy on Sparkling Bog North is equipped with a thermistor chain that measures water temperature at the surface, at 0.25 m and at every .5 m from 0.5 m to 4.5 m. The buoy is also equipped with a dissolved oxygen sensor, meteorological sensors, a CO2 sensor and a YSI AutoProfiler that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Prior to May 2009, data were collected at 1 minute or 10 minute intervals. Since May 2009, data are being collected each minute. Hourly and daily water temperature averages are computed from high resolution data. Hourly and daily values may not be current with high resolution data. In 2008, the instrumented buoy was deployed in Sparkling Bog North from March 24 to November 10. In 2009, the buoy was deployed on the ice on March 7 and was not removed for the winter of 2009 to 2010. Sampling Frequency: varies for instantaneous sample.
Short Name
NSPBBUOY2
Version Number
18

North Temperate Lakes LTER: High Frequency Water Temperature Data - Lake Mendota Buoy 2006 - current

Abstract
The instrumented buoy on Lake Mendota is equipped with a thermistor chain that measures water temperature. In 2006, the thermistors were placed every 0.5m from the surface through 7m and every 1m from 7m to 15m. In 2007and 2008, the thermistors were placed every 0.5 m from the surface through 2m and every 1m from 2m to 20m. The sensor at the water surface is as close to the surface as feasible. The sensor housing itself is ~5cm long, so we have it at about 1 to 6cm deep.The Lake Mendota buoy is also equipped with a dissolved oxygen sensor and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are collected every minute. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. Hourly and daily water temperature averages are computed from high resolution (1 minute) data. Hourly and daily values may not be current with high resolution data.Deployment dates: 2006: June 27-Oct 17; 2007: May 18-Oct 22; 2008: June 26-Nov 4; 2009: April 17-Nov 23; 2010: April 9-Nov 10; 2011: May 19-Nov 11; 2012: April 30-Nov 30; 2013: April 27-Oct 27; 2014: May 4-Oct 12; 2015: June 25-Sept 1; 2016: March 29-Dec 12; 2017: April 23 - Nov 13; 2018: April 11-Nov 15; 2019: April 16-Nov 11; 2020: April 2-Nov 21;
Sampling Frequency: one minute. Number of sites: 1
Core Areas
Dataset ID
130
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented buoy on Lake Mendota is equipped with a thermistor chain that measures water temperature. In 2006, the thermistors were placed every 0.5m from the surface through 7m and every 1m from 7m to 15m. In 2007and 2008, the thermistors were placed every 0.5 m from the surface through 2m and every 1m from 2m to 20m. The Lake Mendota buoy is also equipped with a dissolved oxygen sensor and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are collected every minute. After correcting for flux to or from the atmosphere and vertical mixing within the water column, high frequency measurements of dissolved gases such as carbon dioxide and oxygen can be used to estimate gross primary productivity, respiration, and net ecosystem productivity, the basic components of whole lake metabolism. Hourly and daily water temperature averages are computed from high resolution (1 minute) data. Hourly and daily values may not be current with high resolution data.
Short Name
MEBUOY2
Version Number
30

North Temperate Lakes LTER: High Frequency Water Temperature Data - Lake Mendota Pier 2006 - 2008

Abstract
Water temperature was measured on the pier at 1 and 2 m water depth at a frequency of 1 minute.
Dataset ID
131
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Water temperature was measured on the pier at 1 and 2 m water depth at a frequency of 1 minute.
Short Name
MEPIER2
Version Number
15

Little Rock Lake Experiment at North Temperate Lakes LTER: Physical Limnology 1983 - 2000

Abstract
The Little Rock Acidification Experiment was a joint project involving the USEPA (Duluth Lab), University of Minnesota-Twin Cities, University of Wisconsin-Superior, University of Wisconsin-Madison, and the Wisconsin Department of Natural Resources. Little Rock Lake is a bi-lobed lake in Vilas County, Wisconsin, USA. In 1983 the lake was divided in half by an impermeable curtain and from 1984-1989 the northern basin of the lake was acidified with sulfuric acid in three two-year stages. The target pHs for 1984-5, 1986-7, and 1988-9 were 5.7, 5.2, and 4.7, respectively. Starting in 1990 the lake was allowed to recover naturally with the curtain still in place. Data were collected through 2000. The main objective was to understand the population, community, and ecosystem responses to whole-lake acidification. Funding for this project was provided by the USEPA and NSF. Parameters characterizing the physical limnology of the treatment (north basin, stations 1 and 3) and reference basin (south basin, station 2 and 4) are usually measured at one station in the deepest part of each basin (stations 1 and 2) at 0.5 to 1-m depth intervals depending on the parameter. Parameters measured at depth include water temperature, vertical penetration of photosynthetically active radiation (PAR), dissolved oxygen, chlorophyll and phaeopigments. Additional derived parameters include fraction of surface PAR at each depth and percent oxygen saturation. Auxiliary data include time of day, air temperature, cloud cover, and wind speed and direction and secchi depth. Sampling Frequency: varies - Number of sites: 4
Core Areas
Dataset ID
248
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Reading Temperature and Dissolved Oxygen1. Before leaving to sample a lake, check to make sure that there are no air bubbles under the probe membrane of the YSI TemperatureorDissolved Oxygen meter. If there are air bubbles or if it has been several months since changing the membrane (or if the instrument does not calibrate well or the oxygen readings wander), change the membrane as explained in the manual. Note: We have always used the Standard membranes. If adding water to new membrane fluid bottle (KCl), make sure to add Milli-Q water and not the CFL distilled water.2. Be sure to always store the probe in 100percent humidity surrounded by a wet sponge or paper towel.3. Turn on the temperatureordissolved oxygen meter at least 30 minutes before using it. It is best to turn it on before leaving to sample a lake as it uses up batteries slowly.4. Calibrate the meter using the chart on the back of the instrument (adjusted to the Madison altitude - 97percent oxygen saturation). Leave the plastic cap on the probe (at 100percent humidity). The temperature should not be changing during the calibration. Zero the instrument. When the temperature equilibrates, adjust the oxygen to correspond to the chart. After calibrating the instrument, switch the knob to percent oxygen saturation to make sure it is close to 97percent.5. Take readings at 1 meter intervals making sure to gently jiggle the cord when taking the oxygen readings (to avoid oxygen depletion). Jiggling the cord is not necessary if using a cable with a stirrer. Take half meter readings in the metalimnion (when temperature andoror oxygen readings exhibit a greater change with depth). A change of temperature greater than 1degreeC warrants half-meter intervals.6. Record the bottom depth using the markings on the temp.oroxygen meter cord and take a temperature and dissolved oxygen reading with the probe lying on the lake bottom. Dont forget to jiggle the probe to remove any sediment.7. If any readings seem suspicious, check them again when bringing the probe back up to the surface. You can also double check the calibration after bringing the probe out of the water (and putting the cap back on). Light (PAR) extinction coefficient is calculated by linearly regressing ln (FRLIGHT (z)) on depth z where the intercept is not constrained. FRLIGHT(z) = LIGHT(z) or DECK(z) where LIGHT(z) is light measured at depth z and DECK(z) is light measured on deck (above water) at the same time.For open water light profiles, the surface light measurement (depth z = 0) is excluded from the regression.For winter light profiles taken beneath the ice, the first light data are taken at the bottom of the ice cover and are included in the regression. The depth of uppermost light value is equal to the depth of the ice adjusted by the water level in the sample hole, i.e., the depth below the surface of the water. The water level can be at, above or below the surface of the ice. If the water level was not recorded, it is assumed to be 0.0 and the calculated light extinction coefficient is flagged. If ice thickness was not recorded, a light extinction coefficient is not calculated.For light data collected prior to March, 2007, light values less than 3.0 (micromolesPerMeterSquaredPerSec) are excluded. For light data collected starting in March 2007, light values less than 1.0 (micromolesPerMeterSquaredPerSec) are excluded. Except for bog lakes before August 1989, a light extinction coefficient is not calculated if there are less than three FRLIGHT values to be regressed. For bog lakes before August 1989, a light extinction coefficient is calculated if there are least two FRLIGHT values to be regressed. In these cases, the light extinction coefficient is flagged as non-standard.FRLIGHT values should be monotonically decreasing with depth. For light profiles where this is not true, a light extinction coefficient is not calculated.For samples for which light data at depth are present, but the corresponding deck light are missing, a light extinction coefficient is calculated by regressing ln (LIGHT (z)) on depth z. Note that if actual deck light had remained constant during the recording of the light profile, the resulting light extinction coefficient is the same as from regressing ln(FRLIGHT(z)). In these cases, the light extinction coefficient is flagged as non-standard.
Short Name
LRPHYS1
Version Number
4

Landscape Position Project at North Temperate Lakes LTER: Vertical Lake Profiles 1998 - 1999

Abstract
Parameters characterizing the chemical limnology and spatial attributes of 45 lakes were surveyed as part of the Landscape Position Project. Parameters are measured at or close to the deepest part of the lake. A vertical profile of temperature, dissolved oxygen, and conductivity are collected at 1 meter increments Sampling Frequency: generally monthly for one summer; for some lakes, one or two samples in one summer Number of sites: 45
Dataset ID
95
Date Range
-
Maintenance
completed
Metadata Provider
Methods
We sample at the deepest part of the lake, taking a temperature and oxygen profile at meter intervals from the surface to within 1 meter of the bottom using a YSI Pro-ODO temp/DO meter.
Short Name
LPPPROF1
Version Number
19

North Temperate Lakes LTER: Northern Highlands Stream Chemistry Survey 2006

Abstract
We compared regional patterns in lake and stream biogeochemistry in the Northern Highlands Lake District (NHLD), Wisconsin, USA to ask how regional biogeochemistry differs as a function of the type of ecosystem considered (i.e., lakes versus streams); if lake-stream comparisons reveal regional patterns and processes that are not apparent from studies of a single ecosystem type; and if characteristics of streams and lakes scale similarly. Fifty-two streams were sampled using a stratified random design to determine regional distribution of 21 water chemistry variables during summer baseflow conditions.Sampling Frequency: once per site Number of sites: 52
Contact
Core Areas
Dataset ID
254
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Site SelectionBecause lakes are a dominant feature of the region and stream characteristics could potentially differ based on their hydrologic connections to lakes, we classified streams into three categories as a function of their hydrologic connections to lakes. The first category was streams that had no lakes within the drainage network upstream of the sampling location. The second category was streams that originated from headwater lakes (i.e., no stream inlet but a stream outlet) and the headwater lake was the only lake in the drainage network above the sampling location. The final category had at least a single drainage lake (i.e., a lake with both stream inlet(s) and outlet) in the drainage network above the sampling location. We then used these categories to select sampling sites using a stratified random design for a variety of chemical and physical characteristics.All streams identified on 1:24,000 7.5 inch USGS topographical maps that crossed access points were selected as potential sampling locations and assigned to one of the three stream types. A stream could be classified by more than a single category depending on the sampling location within the drainage network. However, a single drainage network was never sampled more than once to ensure sample independence. Of the 500 possible sampling locations, 52 sites were selected and sampled.SamplingAll streams were sampled 7-10 channel widths upstream of an access point to minimize any influences caused by culverts and other features. Water samples were collected from the center of the channel using a peristaltic pump. Stream discharge was measured after Gore (2007) using cross sectional area and water velocity.Chemical AnalysesAll samples for both studies were collected and processed following the North Temperate Long Term Ecological Research (NTL-LTER) protocols (http://lter.limnology.wisc.edu). Filtering was done in the field using an in-line 0.45 μm membrane filter. All samples were stored on ice and returned to the laboratory where they were preserved according to NTL-LTER protocols. Acid neutralizing capacity (ANC) was determined by Gran titration (APHA 2005). DOC was measured on a Shimadzu TOC-V carbon analyzer. Total nitrogen and phosphorus (unfiltered, TN and TP; filtered, TDN and TDP), nitrate+nitrite (NO3-N), and ammonium (NH4-N) were quantified with an Astoria-Pacific segmented flow auto-analyzer. Soluble reactive phosphorus (SRP) in streams was measured colormetrically on a Beckman DU-800 spectrophotometer (APHA 2005). Anions (Cl- and SO4 2-) were measured using a Dionix DX-500 ion chromatograph and cations (Ca, Mg, Na, K, Fe, K, and Mn) on a Perkin Elmer ICP mass spectrometerDissolved inorganic carbon (DIC) and pH were quantified differently in the lakes and stream data sets. For the lakes data, DIC was determined with a Shimadzu TOC-V carbon analyzer, whereas DIC for the streams dataset was determined by headspace equilibration of acidified water samples in the field and direct measurement of carbon dioxide (CO2) gas on a Shimadzu gas chromatograph (Cole et al. 1994). pH measurements for the lakes dataset were quantified on non-air equilibrated samples in the lab with a Accumet 950 pH meter while direct measurements were taken in the field for the streams dataset using a hand-held Orion model 266 pH meter that was allowed to equilibrated about 20 min in the center for the stream channel.Several variables presented in this study were determined from calculations based on measured values. In streams, dissolved organic nitrogen and phosphorus (DON and DOP, respectively) were determined by the difference between inorganic nutrients and total dissolved nutrients (e.g., DOP = TDP-SRP). We were unable to determine DON in lakes due to the lack of inorganic nitrogen data. It was assumed that DOP approximately equals TDP in lakes because dissolved inorganic phosphorus concentrations in the region are typically below detection limits in the epilimnion during the summer months and consequently not quantified (NTL-LTER unpublished data).
Short Name
LOTTIG2
Version Number
19

Lake Mendota Phosphorus Entrainment at North Temperate Lakes LTER 2005

Abstract
This dataset contains total (TP) and soluble reactive phosphorus (SRP) data collected in Lake Mendota during the summer of 2005 between 6/28/2005 and 10/14/2005 as well as high-resolution temperature data for that same time period . The phosphorus data were taken at five different locations where buoys were deployed. The buoys were deployed with HOBO temperature data loggers attached at 2 - 4 m intervals. Similarly the phosphorus samples were collected at 2 - 4 m intervals throughout the water column. The position of the five buoys changed a few times during the summer in an effort to monitor circulation patterns due to different wind directions and speeds. Manuscript using this dataset: Kamarainen, A.M., H. Yuan, C. Wu, S.R. Carpenter. 2009. One-dimensional and three-dimensional approaches converge on similar estimates of phosphorus entrainment in Lake Mendota. Limnology and Oceanography Methods 7:553-567 Sampling frequency: Water temperature: generally 1 min; some at 5 min. TP and SRP: approximately at 2 weeks intervals Number of sites: 12
Core Areas
Dataset ID
258
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Kamarainen, A.M., H. Yuan, C. Wu, S.R. Carpenter. 2009. One-dimensional and three-dimensional approaches converge on similar estimates of phosphorus entrainment in Lake Mendota. Limnology and Oceanography Methods 7:553-567
Short Name
KAMWT05
Version Number
15
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