US Long-Term Ecological Research Network

Cascade Project at North Temperate Lakes LTER Core Data Physical and Chemical Limnology 1984 - 2016

Abstract
Physical and chemical variables are measured at one central station near the deepest point of each lake. In most cases these measurements are made in the morning (0800 to 0900). Vertical profiles are taken at varied depth intervals. Chemical measurements are sometimes made in a pooled mixed layer sample (PML); sometimes in the epilimnion, metalimnion, and hypolimnion; and sometimes in vertical profiles. In the latter case, depths for sampling usually correspond to the surface plus depths of 50percent, 25percent, 10percent, 5percent and 1percent of surface irradiance.
Dataset ID
352
Date Range
-
Methods
Methods for 1984-1990 were described by Carpenter and Kitchell (1993) and methods for 1991-1997 were described by Carpenter et al. (2001).
Version Number
14

Upper Midwest Great Lakes Region Citizen Secchi Data 1938 - 2012

Abstract
Upper MidwestorGreat Lakes Region Citiizen Secchi Data includes 239,741 citizen Secchi monitoring records (1938 – 2012) from Illinois Volunteer Lake Monitoring Program, Indiana Clean Lakes Program, Iowa Secchi Dip-In Project, Michigan Clean Water Corps, Lakes of Missouri Volunteer Program, Minnesota Citizen Lake Monitoring Program, Ohio Citizen Lake Awareness Program, and Wisconsin Citizen Lake Monitoring Records. Data were obtained from above monitoring groups and merged with the high resolution National Hydrography Dataset based on citizen proved latitudeorlongitude coordinates to verify the location of individual lakes and size of lake (hectare). Code used to estimate annual average Secchi depth (m) provided in metadata. These citizen-collected, publically available Secchi depth measurements were collected to answer two questions: (1) what are the long-term trends in lake water quality across a broad geographic region?; (2) how do trends differ as a function of spatial location, size of lake monitored, and when Secchi records were collected. Data collection and analysis were funded by the National Science Foundation (MSB- 1065786, EF-1065818, EF-1065649), NTL-LTER (DEB-0822700), STRIVE grant 2011-W-FS-7 from the Environmental Protection Agency. GLERL contribution number (1703).
Contact
Dataset ID
300
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Secchi monitoring records (1938 – 2012) were obtained from Illinois Volunteer Lake Monitoring Program, Indiana Clean Lakes Program, Iowa Secchi Dip-In Project, Michigan Clean Water Corps, Lakes of Missouri Volunteer Program, Minnesota Citizen Lake Monitoring Program, Ohio Citizen Lake Awareness Program, and Wisconsin Citizen Lake Monitoring Records. Data were obtained from above monitoring groups and merged with the high resolution National Hydrography Dataset (www.nhd.usgs.gov) based on citizen proved latitudeorlongitude coordinates to verify the location of individual lakes and size of lake (hectare). [R] code used to estimate annual average Secchi depth (m) provided in metadata.
NTL Keyword
Short Name
GLR Secchi
Version Number
17

LTREB Chemical and Physical Limnology at Lake Myvatn 2012-current

Abstract
These data are part of a long-term monitoring program at station 33 in the central part of Myvatn that represents the dominant habitat, with benthos consisting of diatomaceous ooze. The program was designed to characterize import benthis and pelagic variables across years as midge populations varied in abundance. Starting in 2012 samples were taken at roughly weekly inervals during June, July, and August, which corresponds to the summer generation of the dominant midge, Tanytarsus gracilentus.
Creator
Dataset ID
287
Date Range
-
Maintenance
Ongoing
Metadata Provider
Methods
Water Profile1. Take Light, DO, pH, Temp profile every 0.5mUse YSI DO probe, pH meter, and Li Cor light meter. Take the light profile from the sunny side of the boat.2. Take Secchi depthLower Secchi disk slowly until you can never see clear boundaries between white and black quarters, record this distance to the surface of the water as lower Secchi disk observation. Then pull the Secchi up until you can always see clear boundaries between white and black quarters, record this distance to the surface as the upper Secchi observation.Benthic Net Primary Production1. Measure light, temperature, percentDO, DO, and pH at 0.5m intervals at the sampling location.2. Take 10 clean/undisturbed cores. Try to get a uniform distance between the sediment and top of tube, so the cores have the same volume of water. Cover in boat with tarp to exclude light.3. Collect water from the shore of the boat and measure temp, percentDO, and DO. Save in bucket.4. Measure light intensity at 0 (out) and 0.5m depth where the cores will be incubated.5. Set up HOBO light recorder on the incubator.6. For each tube, take initial temp, percentDO, and DO. Before taking DO measurement, move the DO probe up and down three times to ensure no DO gradient (but do not disturb sediment). Add, slowly and without bubbling, 10 to 20mL of water (just the amount needed) to the core from bucket (number 3) to ensure no air space, and replace the stopper. Measure the distance from sediment to bottom of stopper to the nearest 0.5cm (column_depth).7. Place cores 1, 3, 5, and 7 in dark chambers (opaque tubes), so there are 4 dark and 6 light treatments.8. Incubate the cores using the metal structure at saturation light intensity if possible (300 mol per meter squared per second at 0.5m depth) for about 3h.9. Before taking DO measurement, move the DO probe up and down three times to ensure no DO gradient (but do not disturb sediment), and then measure percentDO, DO, and temperature in each core.Light controlsOnce a month (June, July, August), on a sunny day, incubate 10 cores for 3h with different light intensities to determine primary productivity under different light intensities and different temperatures. It would be best to do this the day after routine sampling (i.e., when retrieving the benthic sampler) so that the results can be compared to those from the routine sampling. Different light levels are obtained using white mesh bags around the core tubes.Core 1 and 6, lightCore 2 and 7, 2xCore 3 and 8, 4xCore 4 and 9, 8xCore 5 and 10, darkIMPORTANT: After the incubations, measure light intensity inside a core tube covered for the different treatments. This is done by removing the light meter from the metal holder and placing it facing up in a core using zip ties and a blue stopper at the bottom. Then place treatment bags over the top and measure light when holding the core at the level they reach in the incubator; use the marking on the light meter cord to make sure this is standardized for all measurements. This should be done 8 times total (each bag plus twice without bags).Light saturationOnce a month in the summer of 2013, we conducted sediment core incubations with varying amounts of shade cloth applied to the cores. Sediment cores received 0, 2, 4, 8, or 15 layers of shade cloth, with two cores in each treatment. All cores were then incubated in the lake over the same 3hr period at a depth of 0.5m.Sediment Dry Weight and Weight on Combustion1. Remove 0.75cm of sediment from a core into a plastic deli container. This should be done on a fresh core. This is the same sample that is used for chl analysis.2. Subsample 5 to 10mL sediment solution and place in a pre-weighed tin tray in oven at 60C for at least 12 hours. When dry, weigh for dry weight.In 2014, the method for sampling benthic chlorophyll changed. Sediment Dry Weight measurements were taken from these samples as well. Below is the pertinent section from the methods protocols. Processing after the collection of the sample was not changed.Take sediment samples from the 5 cores collected for sediment characteristics. Take 4 syringes of sediment with 10mL syringe (15.3 mm diameter). Take 4-5cm of sediment. Then, remove bottom 2cm and place top 2cm in the film canister.3. Combust at 550C for 4.5 hours. Weigh tray.4. If not analyzing combusted samples immediately, place in drying oven before weighing.
Version Number
15

North Temperate Lakes LTER: Physical Limnology of Lake Kegonsa and Lake Waubesa 1995 - current

Abstract
Parameters characterizing the physical limnology of Lakes Waubesa and Kegonsa are measured at one station in the deepest part of each lake at 0.5-m to 1-m depth intervals. Measured parameters in the data set include water temperature and dissolved oxygen, as well as the derived parameter percent oxygen saturation.Number of sites: 2Sampling Frequency: bi-weekly during ice-free season from late March or early April through early September, then every 4 weeks through late November; sampling is conducted usually once during the winter (depending on ice conditions).
Dataset ID
264
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
G. Reading Temperature and Dissolved Oxygen 1. 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).
Short Name
KEWAPH01
Version Number
21

Light Extinction

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) / 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.

North Temperate Lakes LTER: Light Extinction - Trout Lake Area 1981 - current

Abstract
A light (PAR) extinction coefficient is calculated for the water column for the seven northern study lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog]). The fraction of surface light is computed at 0.25-m to 1-m depth intervals depending on the lake. The light (PAR) extinction coefficient is calculated by regressing ln(fraction of light(z)) on depth z. Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season Number of sites: 7
Dataset ID
259
Date Range
-
LTER Keywords
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.
Short Name
NTLPH08
Version Number
15

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
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