US Long-Term Ecological Research Network

Microbial Observatory at North Temperate Lakes LTER Summary of Microbial Activity 2000 - 2002

Abstract
Summary of Microbial Observatory data from the bacterial production, planktonic respiration and alakline phosphatase activity databases, plus bacterial cell counts from epifluorescence microscopy using DAPI cell stain. Information on integrated sample depth and incubation temperature is also included Sampling Frequency: fortnightly during ice-free season - every 6 weeks during ice-covered season Number of sites: 4
Core Areas
Dataset ID
46
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
this is a summary dataset based on knb-lter-ntl.45, knb-later-ntl.50, and knb-lter-ntl.51 where the methods are described in detail. in addition bacterial cell counts were optained from epifluorescence microscopy using DAPI cell stain.
Short Name
MOACT2
Version Number
4

Lake Metabolism at North Temperate Lakes LTER 2000

Abstract
Recent literature suggests that for many lakes and rivers, the respiratory breakdown of organic matter (R) exceeds production of organic matter by photosynthesis (gross primary production; GPP) within the water body. This metabolic balance (GPP less than R; heterotrophy ) implies that allochthonous organic matter supports a portion of the aquatic ecosystems respiration. Evidence that many lakes are heterotrophic comes from diverse approaches, and debate remains over the circumstances in which heterotrophy exists. The methods used to estimate GPP and R and the limited extent of lake types studied, especially with respect to dissolved organic carbon (DOC) and total phosphorus (TP) concentrations, are two reasons for differing conclusions. In this study, O2 and CO2 sondes were deployed during July and August, 2000 to measure diel gas dynamics in the surface waters of 25 lakes in the Northern Highland Lake district of Wisconsin and the Upper Peninsula of Michigan. The lakes were chosen to span wide and orthogonal ranges in DOC and TP concentrations. From these data, we calculated GPP, R and net ecosystem production (NEP=GPP-R). Over the broad range in TP and DOC among the lakes, diel CO2 and O2 changed on a near 1:1 molar ratio. Metabolism estimates from the two gases were comparable, except at high pH. Most lakes in our data set had -NEP, but GPP and R appeared to be controlled by different factors. TP correlated strongly with GPP, whereas DOC correlated with R. At low DOC concentrations, GPP and R were nearly equal, but at higher DOC, GPP and R uncoupled and lakes had -NEP. Strong correlations between lake metabolism and landscape related variables suggest that allochthonous carbon influences lake metabolism. Sampling Frequency: Chemical parameters and physical properties sampled from 1 to 4 times during the summer. Time series data step is 30 minutes. Number of sites: Time series data for 25 lakes. Chemical and physical data from 31 lakes.
Core Areas
Dataset ID
110
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
Study sitesWe sampled surface waters of 31 lakes in the Northern Highland Lake district of Wisconsin and the Upper Peninsula of Michigan during July and August of 2000 (Table 1). The lakes were chosen to span wide and orthogonal ranges in DOC and TP concentrations and for their close proximity to the Trout Lake Station in Vilas county, Wisconsin. The order in which the lakes were sampled was randomized.Limnological samplesLimnological samples were collected for each lake at 0.5 m depth as follows. DOC samples were collected as the filtrate through Whatman GForF filters, and were analyzed on a Shimadzu model 5050 high temperature TOC analyzer. Color was also measured from this filtrate as absorbance at 440 nm on a Spectronic Genesys 2 spectrophotometer using 10 cm quartz cuvettes. Chlorophyll a was collected by filtering 200 ml of lake water, and then freezing filters for at least 24 hours, followed by methanol extraction for 24 hours. Fluorescence was determined before and after acidification to correct for pheopigments. Total phosphorus was analyzed on a Lachat autoanalyzer after persulfate digestion of a whole water sample. DIC and was measured on a Shimadzu GC-8AIT (TCD detector) gas chromatograph. DIC was determined from the headspace of acidified samples, which was injected into the GC. pH was measured using an Orion digital pH meter with automatic temperature compensating electrode. Temperature and dissolved oxygen profiles were measured using a YSI temperatureordissolved oxygen meter. Spot measurements of surface water DO were made on quadruplicate samples, using Winkler titrations as described in Bade and others (1998).BuoysWe deployed a buoy that sampled dissolved CO2, DO, water temperature, photosynthetically active radiation (PAR), and wind speed for 2-4 days on each lake. All water measurements were made at a depth of 0.5 m. Wind speed was measured one meter above the lake, using an RM Young model 03001, and PAR was measured 10 cm above the lake surface using a Li-Cor model 190SA quantum sensor. Electronic control and data collection were managed by a Campbell Scientific CR10X data logger. DO and water temperature were measured with a YSI model 600-XLM sonde fitted with a Rapid Pulse oxygen probe (model 6562) and temperature sensor. The sonde was attached to the buoy at the opposite end from the CO2 equilibration chamber (described below).We measured dissolved CO2 independently from DO. We equilibrated a closed loop of atmospheric gas in an equilibration chamber submerged to 0.5 m. The equilibrated gas volume was about 234 ml. We recirculated gas for the last 10 minutes of every 30 minute period, with a flow rate of about 9 ml s-1. A pump exchanged lake water every minute during equilibration. Equilibrated gas was diverted to the IRGA, equipped with a 14 cm sample cell for lakes with CO2 concentration under 2000 ppm or a 5 cm sample cell for lakes with CO2 concentration between 2000-20000 ppm. Following analysis of equilibrated gas, solenoids were activated to route atmospheric gas (taken 10 cm above the water) for CO2 analysis.Time series data are included for 25 of the lakes.Additional detail of the methods available in Hanson et al. (2003)Hanson, P. C., D. L. Bade, S. R. Carpenter, and T. K. Kratz. 2003. Lake metabolism: Relationships with dissolved organic carbon and phosphorus. Limnol. Oceanogr. 48: 1112-1119.
Short Name
LAKEMET1
Version Number
5

Cascade Project at North Temperate Lakes LTER: Process Data 1984 - 2007

Abstract
Data on chlorophyll, primary productivity, and alkaline phosphatase activity from 1984-2007. Samples were collected with a Van Dorn bottle at 6 depths determined from the percent of surface irradiance (100%, 50%, 25%, 10%, 5% and 1%) and in the hypolimnion (12 m in Peter, East Long, West Long, and Tuesday lakes; 9 m in Paul Lake; and 4.5 m in Central Long Lake). Sampling Frequency: varies Number of sites: 8
Core Areas
Dataset ID
73
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
CHLOROPHYLL a ANALYSISEQUIPMENT: Film canistersTurner 450 Fluorometer fitted with:1. Quartz-halogen lamp2. Emission filter -SC6653. Excitation filter -NB44047mm Whatman GForF filters12 x 75 mm disposable glass culture cuvettes (Do not reuse cuvettes!)1-5 mL Oxford pipettorFinnpipette Stepper Pipetter with 5 mL tiptimestimesNOTEtimestimes-Change filters with fluorometer off! (Remember that chlorophyll analysis filters are different from APA analysis filters.)-Make sure Fluorometer has been calibrated for chlorophyll a (see Fluorometer Calibration for Chlorophyll a Analysis).REAGENTS: 100percent Methanol, spectrophotometric gradeCAUTION - wear gloves whenever you use methanol.0.1 N HCLEthidium Bromide Stock 3 standard (40microM solution)PROCEDURE:A. Filter water samples from each of the 6 light-depths onto a 47 mm GForF filter.1. Filters have a grid side and a smooth side. Place filter smooth side up.2. Shake sample bottle well before filtering (do this after the DIC sample has been taken from the same bottle.)3. For each depth, filter enough water so there is a faint color on the filter. For our lakes this ranges between 100-300ml. Record the volume filtered. Make sure you filer at less than 200 mm Hg pressure.4. Rinse filter towers and filters with DI water, place filters in labeled film canisters and place in freezer. Labels should include lake, date, and depth ID.5. If measuring edible chlorophyll as well, repeat steps 1-4 above, but first filter the sample through 35 microm mesh. (This has not been done since 2001, inclusive.)B. Extraction - DO IN DIM LIGHT and WEAR GLOVES!!1. Remove one tray of film canisters from the freezer. Extract chlorophyll by adding 25 mL 100percent MeOH to each film canister. If using re-pipettor, verify dispensed volume. (Record extraction volume if different from 25 mL.) Note the extraction time for each group of samples.2. Re-cap and place canisters in refrigerator to extract for exactly 24 hours (in the dark).3 Repeat steps 1 and 2 for all trays that have been in the freezer more than 24 hours.C. FluorometryCalibration of the fluorometer using a chlorophyll standard is typically performed at the beginning of the field season, or when a bulb is changed. Calibration using Ethidium Bromide is done at the beginning of each sample set.1. Insert correct filters in fluorometer while fluorometer is off. (Emission filter -SC665, Excitation filter -NB440), and warm it up for 1 hour .2. TURN LIGHTS OUT. Chlorophylls must be read in low light and samples must be kept cool. Do not remove film canisters from the refrigerator until you are ready to process the samples.3. Place clean cuvettes into a labeled rack (12 cuvettes per rack). Remove one lake-day of film canisters from the refrigerator.4. Place Ethidium Bromide Stock 3 standard into fluorometer and record reading on datasheet. Then, turn the span knob until the reading is 908. Record this on the datasheet.5. Shake film canister, remove the lid, and rinse the pipette tip with 2.5 mL of the sample. Then remove 2.5 mL of sample and place in cuvette.times Repeat for all film canisters.6. Pipette 2.5 mL of 100percent methanol into a cuvette for the blank and use it to zero the fluorometer. Choose a gain and turn the zero knob until the fluorometer reads 000. You must zero the machine every time you change gains.7. Remove the first sample cuvette from the rack, wipe with a Kimwipe, and place in fluorometer. Record the gain and the fluorescence before acidification, Fb. Repeat for all 12 cuvettes in the rack. Readings should be between about 200 and 1000. If not, adjust the gain and re-zero.8. Acidify each cuvette with 100 microL 0.0773 N HCl using the repeating pipetter and mix (hold the top of the cuvette securely, then "thump" the bottom several times). Check for condensation on the outside of the cuvettes, and wipe with a Kimwipe if necessary. Wait about 1 min from the acidification of the first cuvette.9. Record the fluorescence after acidification for all 12 cuvettes. VERY IMPORTANT: Make sure you read the Fb and Fa values for each sample on the same gain.10. Remove a new lake-day batch of film canisters from the refrigerator and repeat steps 3-9.times if particulate matter is present, centrifuge sample for 10 min. and use supernatant.D. Clean Up: DO THIS UNDER THE HOOD!1. Dump methanol solution from cuvettes and film canisters into a metal tray. Place the film canisters and lids in a separate tray. Position them in one layer on the tray with their openings facing up. Leave the trays under the hood overnight to evaporate the methanol.REFERENCES:Marker, A.F.H., C.A. Crowther, and R.J.M. Gunn. 1980. Methanol and acetone as solvents for estimating chlorophyll a and phaeopigments by spectrophotometry. Arch. Hydrobiol. Beih. Ergebn. Limnol 14: 52-69.Strickland, J.H. and T.R. Parsons. 1968. A practical handbook of seawater analysis. Fish. Res. Brd. Can. Bulletin 167.pp. 201-206.Holm-Hansen, O. 1978. Chlorophyll a determination: improvements in methodology. Oikos 30:438-447.
Short Name
CPROC1
Version Number
6

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Crystal Bog Buoy 2005 - 2014

Abstract
The instrumented buoy on Crystal Bog is equipped with a dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface, thermistors are placed every 0.25m throughout the water column, and meteorological sensors measure wind speed, relative humidity, and air temperature. 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. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples Number of sites: 1
Core Areas
Dataset ID
118
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
see abstract for methods description
Short Name
CBBUOY1
Version Number
11

North Temperate Lakes LTER: High Frequency Water Temperature Data - Crystal Bog Buoy 2005 - 2014

Abstract
The instrumented buoy on Crystal Bog is equipped with a thermistor chain that measures water temperature from depths ranging from the surface to 2.25m placed every 0.25m throughout the water column. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. The Crsytal Bog 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 usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. 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. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples Number of sites: 1
Core Areas
Dataset ID
119
Date Range
-
Maintenance
completed
Metadata Provider
Methods
The instrumented buoy on Crystal Bog is equipped with a thermistor chain that measures water temperature from depths ranging from the surface to 2.25m placed every 0.25m throughout the water column. The Crsytal Bog 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 usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. 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. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples
Short Name
CBBUOY2
Version Number
26

Cascade Project at North Temperate Lakes LTER: Physical and Chemical Limnology 1984 - 2007

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.The 1991-1995 chemistry data obtained from the Lachat auto-analyzer. Like the process data, there are up to seven samples per sampling date due to Van Dorn collections across a depth interval according to percent irradiance. Voichick and LeBouton (1994) describe the autoanalyzer procedures in detail.Methods for 1984-1990 were described by Carpenter and Kitchell (1993) and methods for 1991-1997 were described by Carpenter et al. (2001).Carpenter, S.R. and J.F. Kitchell (eds.). 1993. The Trophic Cascade in Lakes. Cambridge University Press, Cambridge, England.Carpenter, S.R., J.J. Cole, J.R. Hodgson, J.F. Kitchell, M.L. Pace,D. Bade, K.L. Cottingham, T.E. Essington, J.N. Houser and D.E. Schindler. 2001. Trophic cascades, nutrients and lake productivity: whole-lake experiments. Ecological Monographs 71: 163-186.Number of sites: 8
Dataset ID
71
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
The 1991-1995 chemistry data obtained from the Lachat auto-analyzer. Like the process data, there are up to seven samples per sampling date due to Van Dorn collections across a depth interval according to percent irradiance. Voichick and LeBouton (1994) describe the autoanalyzer procedures in detail.Methods for 1984-1990 were described by Carpenter and Kitchell (1993) and methods for 1991-1997 were described by Carpenter et al. (2001).Carpenter, S.R. and J.F. Kitchell (eds.). 1993. The Trophic Cascade in Lakes. Cambridge University Press, Cambridge, England.Carpenter, S.R., J.J. Cole, J.R. Hodgson, J.F. Kitchell, M.L. Pace,D. Bade, K.L. Cottingham, T.E. Essington, J.N. Houser and D.E. Schindler. 2001. Trophic cascades, nutrients and lake productivity: whole-lake experiments. Ecological Monographs 71: 163-186.Number of sites: 8
Short Name
CPHYS1
Version Number
4

North Temperate Lakes LTER: Spatially Distributed Water Temperature (2004,2006) and Sediment Temperature (2006) of Lake Wingra

Abstract
Profiles of water and sediment temperature were measured during the summer months in Lake Wingra, Dane County, WI, USA at several locations. During the months July through September, 2004, water temperature profiles were measured. For the months, June through August, 2006, sediment temperatures were measured along with the water temperature profiles. Sampling Frequency: 2 minutes and 4 minutes Number of sites: 3 sites each summer Instrument: http://www.microdaq.com/occ/u22/underwater_temperature_data_logger.php - Underwater Temperature Data Logger
Dataset ID
211
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
using a Onset HOBO Underwater Temp Logger for Extended Deployment in Fresh or Salt Water Profiles of water and sediment temperature were measured during the summer months in Lake Wingra, Dane County, WI, USA at several locations. During the months July through September, 2004, water temperature profiles were measured. For the months, June through August, 2006, sediment temperatures were measured along with the water temperature profiles.
Short Name
YUAN1
Version Number
19

North Temperate Lakes LTER: High Frequency Meteorological and Dissolved Oxygen Data - Trout Lake Buoy 2004 - current

Abstract
The instrumented buoy on Trout Lake is equipped with a dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface. Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, photosynthetically active radiation (PAR), and barometric pressure. Starting in 2005, thermistors were placed every 0.5-1m from the surface through 14m and every 2 to 4m from 14m to the bottom of the water column at 31m. In July 2006, a new thermistor chain was deployed with thermistors placed every meter from the surface through a depth of 19 meters. 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. Data are averaged to daily values from one minute samples for years 2005 - 2006. Daily values are computed from high resolution data starting in year 2007. Data are averaged to hourly values from one minute samples for years 2005 - 2008, Hourly values are computed from high resolution data starting in year 2009. Hourly and daily values may not be current with high resolution data in the current year. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples Number of sites: 1
Core Areas
Dataset ID
117
Date Range
-
Maintenance
ongoing
Metadata Provider
Methods
The instrumented buoy on Trout Lake is equipped with a dissolved oxygen sensor, a thermistor chain, and meteorological sensors that provide fundamental information on lake thermal structure, weather conditions, and lake metabolism. Data are usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. The D-Opto dissolved oxygen sensor is 0.5m from the lake surface. Meteorological sensors measure wind speed, wind direction, relative humidity, air temperature, photosynthetically active radiation (PAR), and barometric pressure. Starting in 2005, thermistors were placed every 0.5-1m from the surface through 14m and every 2 to 4m from 14m to the bottom of the water column at 31m. In July 2006, a new thermistor chain was deployed with thermistors placed every meter from the surface through a depth of 19 meters. 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. Data are averaged to daily values from one minute samples for years 2005 - 2006. Daily values are computed from high resolution data starting in year 2007. Data are averaged to hourly values from one minute samples for years 2005 - 2008, Hourly values are computed from high resolution data starting in year 2009. Hourly and daily values may not be current with high resolution data in the current year. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples
Short Name
TRBUOY1
Version Number
40

North Temperate Lakes LTER: High Frequency Water Temperature Data - Trout Lake Buoy 2004 - current

Abstract
The instrumented buoy on Trout Lake is equipped with a thermistor chain that measures water temperature from thermistors placed throughout the water column. From 2004 to mid-summer 2006, thermistors were placed every 0.5-1m from the surface through 14m, and every 2 to 4m from 14m to the bottom of the water column at 31m. The surface temperature sensors are attached to floats so that they are as close to the surface as feasible. In July 2006, a new thermistor chain was deployed with sensors placed every meter from the surface through a depth of 19 meters. This configuration lasted through 2008 and was used again 2012-2014. In the period 2009-2011, thermisters were place every meter down to 20m and then every two meters to a final depth of 32m. From 2015 to present, thermistors are spaced 0.25 meters from the surface to 1m, 0.5 meters down to 4 meters depth, and 1m spacing to 14 meters. Four more thermisters are at depths of 16, 20, 25 and 30 meters. Sampling frequency was 10 minutes in 2004-2005 and again 2007-2010. It was 2 minutes in 2006. Since 2011, sampling frequency has been every minute.The Trout Lake 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. 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. Number of sites: 1. Hourly and daily averages are computed from the high resolution data.
Core Areas
Dataset ID
116
Date Range
-
Maintenance
ongoing
Metadata Provider
Short Name
TRBUOY2
Version Number
28

North Temperate Lakes LTER: High Frequency Water Temperature Data - Trout Lake Buoy2 - ADCP 2005 - 2006

Abstract
This instrumented buoy on Trout Lake is equipped with a thermistor chain that measures water temperature from depths placed every 0.5-1m from the surface through 13m. The Trout Lake buoy is also equipped with meteorological sensors that provide fundamental information on lake thermal structure and weather conditions. An acoustic Doppler current profiler (ADCP) is associated with this buoy. Data are usually collected every 10 minutes with occasional periods of 2 minute data for short periods to answer specific questions. 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. Sampling Frequency: varies for instantaneous sample. averaged to hourly and daily values from one minute samples Number of sites: 1
Core Areas
Dataset ID
121
Date Range
-
Maintenance
completed
Metadata Provider
Methods
see abstract for methods description
Publication Date
Short Name
TR2BUOY2
Version Number
22
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