US Long-Term Ecological Research Network


  • clipboard, data sheet, pencils, watch, duct tape                                                             
  • peristaltic pump with attachment for filter holders
  • 12 volt battery and cables to run pump
  • 1/4" I.D. tygon tubing to reach lake, 2000ml graduated cylinder
  • sample bottles:
                         6-125ml nalgene bottles – 2 TP/TN, 2 Conductivity, 2 Color
                         5-20ml scintillation vials - 2 Alkalinity, 4 pH
                         2 glass test tubes for DOC
  • temperature/oxygen meter (YSI-650MDS Sonde)
  • 6 filters per lake (4 - 0.4µ Nuclepore polycarbonate for DOC and color, 2 - 10um for chlorophyll) loaded in filter holders
  • zooplankton and chlorophyll cooler
  • water sample cooler (with icepack during summer) 
  • Wisconsin net with cup, ETOH squirt bottle
  • metered line, Secchi disk
  • oars, cushions and vests, motor, gas
Nucleopore filters
      Load filter holders with filters. Make sure that both plastic filters are snapped into filter holders. Do not use the blue filter dividers as filters. The filters are thin white membranes.

Chlorophyll filters
      Load filter holders with glass fiber filters. The filter should be placed so that the ‘fuzzy’ side faces the input end of the filter holder. Tighten the filter holders gently to avoid tearing the filters. Make sure that you label which filter holders have Nucleopore and which have chlorophyll filters.
Zooplankton Sample Jars
      Label 4-oz jars for Wisconsin net samples. Cover the labels with a strip of clear contact paper, making sure the contact paper completely covers the label and encircles the jar. Replace the manufacturer’s lids with Kols brand lids. Add the date to the label using a ‘Sharpie’ brand permanent marker. Add two 40ml squirts of ethanol (found in the lab refrigerator upstairs) to each jar.
      Weigh the empty zooplankton jars, including lids, on the Mettler PC440 balance. Record these weights on the ‘Volume by Weight’ data sheet.
Take a barometric pressure reading, and record it in on the field data sheet.
Check checklist to be sure you have everything you will need in the field.
 Sonde membrane must be changed every week (or if you are getting strange values) and electrodes should be sanded if they show buildup.
SET UP (on station at the lake)
Record the lake, date, observers, time, and weather information on the data sheet.
Take a measurement of depth using the metered rope and secchi disk.
1      Before leaving Trout Lake Station place the Temp/D.O. probe in a bucket of Trout Lake Water. Soak probe for a half hour (en route) before using.              
2      Remove the probe from the bucket and place in a sealed plastic bag. Make sure the sonde is attached to the handheld monitor.
3      Switch the monitor power on and record a start time when ready to sample.
4      Enter the Sonde Menu and enable the Calibrate command.
5      Press enter on Dissolved Oxygen and then enter on DO%.
6      Type in the barometric pressure.
7      Wait until the DO mg/L field stabilizes (holds a value for approximately 10 seconds) and press enter.
8      Record the DO mg/L at which the sonde was calibrated.
9      Escape back to the sonde main menu and enable the Run command.
10    Take the probe out of the bag and lower it into the water. 
11    Press enter to Start Sampling and record the temperature and DO mg/L readings at each meter interval from the surface (probe just under water surface) to near the bottom. To avoid probe damage and mixing of sediments into the water column, do not lower the probe into the sediments.
12    Record the end time.
13    When finished cover the probe with moist towels and store in a plastic bag. It should always be stored like this when not in use.
During stratification (late May to late October), collect replicate surface water samples from the approximate deepest area of the lake.
Using white labeling tape and a permanent marker, make sure to label every sample with lake abbreviation, date, sample type, and replicate number.
Clear the sample tubing:
The tubing inlet should be a half meter under the water surface. Connect the tubing to the pump and run the pump long enough to flush slightly more than one tubing volume from the tubing. Each meter of 1/4" I.D. tygon tubing holds a volume of approximately 32 ml. Run at least one hundred ml of surface water through the tubing.
Collect the water samples avoiding contamination of bottles or filters:
Rinse each bottle three times with a small amount of the lake water it is to be filled with. Flush each filter by pumping a small amount of lake water through it before collecting any filtered samples. Do not touch inside or rims of bottles, inside of bottle caps, or inlet/outlet holes on the filter holders. Keep used filters out of the clean filter container. Place bottles in a cooler immediately after collection. Keep samples cold and dark until analysis. If the filter holders are leaking, turn off the pump and rethread them without disturbing the filter. Turn the pump speed to low before running the nucleopore filters – if there is too much pressure one of the tubing connections will pop off. These filters also slow very quickly, so take the color samples while the water is still flowing well through the filter and the DOC samples once it has slowed to a drip. 
Sample handling and storage:
We sampled for water chemistry at two levels of intensity in 2001. Routine (once in June and once in August) sampling included collection of samples for total phosphorus/total nitrogen, dissolved organic carbon, color, and chlorophyll. In August we also collected samples for pH, conductivity, and alkalinity. Beginning in 2002 we sampled all parameters only in June with the following exceptions. ** Bad 2001 chlorophyll, DIC/DOC, and color samples were recollected in late May 2002. In 2004 lost DIC/DOC samples were recollected in early September. 
15ml “DOC”
20ml pH
125ml color
125ml conductivity
20ml alkalinity
100ml TP/TN
The ‘TP/TN’ bottles for nutrient analysis should be filled to the shoulder of the bottle and acidified with 1 ml OPTIMA HCl back at the lab.
The water for pH, alkalinity, and DIC/DOC analyses should not be agitated or exposed to air. This is to avoid carbon dioxide loss or invasion. Fill these bottles gently to the top plus some overflow, and carefully screw on the displacement cap so that the sample contains no air bubbles. Invert the bottle and check for bubbles. Dump out and refill if there is a bubble in the sample. 
Record the time you start and finish collection of chemistry samples.


Chlorophyll Samples
Replicate chlorophyll samples are collected at the surface on each lake. Attach the pressure gauge and filter to the pump outlet tubing so that the flow of water passes through the gauge before going through the filter. Pump the water into a 2000ml graduated cylinder. Pump until the pressure gauge reads 15 psi or until 3000 ml have been pumped through the filter, whichever comes first. If 2000ml is pumped before the gauge reaches 15 psi, stop the pump, dump the water from graduated cylinder and continue. At pressures greater than 15 psi some phytoplankton cells are broken, and chlorophyll is washed through the filter instead of being retained on it. Remove the filter holder from the tubing, reverse it, reverse the direction of the pump, and use the pump to suck excess water from the filter holder. Immediately place the filter in a cooler to keep it cold and dark until returning to the lab. Record the filter holder number, maximum psi, and volume filtered on the data sheet.
Wisconsin Net samples
      Lower the Wisconsin net to the bottom sample depth ( top of the net should be one meter above the bottom). Pull it up slowly at a rate of about 3 seconds per meter. A slow haul prevents the net from pushing water and plankton away from the mouth of the net. To drain the cup swirl it until the water level is below the lower mesh window, then pour contents into the sample jar. Avoid inverting the cup while swirling, as you will lose the sample into the net. Rinse the inside of the cup with 95% ETOH several times adding the rinse to the sample jar. Wait until the chemistry crew member is finished taking Temp/D.O. profile before taking the Wisconsin net sample, so as not to stir up the sediments. Take replicate sample.
Secchi Disk
      Lower the Secchi into the water on the shady side of the boat. Lower the disk until you cannot see it; record this depth as the ‘down’ reading. Raise the disk until you can again see it; record this depth as the ‘up’ reading.  
Turn meters off. Record an 'off station' time.
Preserve and store chemistry samples and chlorophyll filters. Do not expose samples to light. Water samples should be stored in the refrigerator downstairs. Chlorophyll filters should be removed from filter holders, placed in 20ml vials, and stored in the freezer downstairs.
pH samples must be run the same day they are taken.
Acidify TP/TN samples with 1ml Optima HCl. 
Wash filter holders, allow to dry. Set bottle bags out to dry.
Rinse and wipe coolers; leave open to dry.
Rinse sample tubing with milliQ. Store tubing full of milliQ.



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