US Long-Term Ecological Research Network

Cascade Project at North Temperate Lakes LTER Core Data Nutrients 1991 - 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. The 1991-1999 chemistry data was 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. Nutrient samples were sent to the Cary Institute of Ecosystem Studies for analysis beginning in 2000. The Kjeldahl method for measuring nitrogen is not used at IES, and so measurements reported from 2000 onwards are Total Nitrogen.
Core Areas
Dataset ID
351
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

Cascade Project at North Temperate Lakes LTER Core Data Carbon 1984 - 2016

Abstract
Data on dissolved organic and inorganic carbon, particulate organic matter, partial pressure of CO2 and absorbance at 440nm. Samples were collected with a Van Dorn sampler. Organic carbon and absorbance samples were collected from the epilimnion, metalimnion, and hypolimnion. Inorganic samples were collected at depths corresponding to 100%, 50%, 25%, 10%, 5%, and 1% of surface irradiance, as well as one sample from the hypolimnion. Samples for the partial pressure of CO2 were collected from two meters above the lake surface (air) and just below the lake surface (water). Sampling frequency: varies; number of sites: 14
Core Areas
Dataset ID
350
Date Range
-
Methods
Detailed field and laboratory protocols can be found in the Cascade Methods Manual, found here: https://cascade.limnology.wisc.edu/public/public_files/methods/CascadeManual1998.pdf
POC, PON and DOC: 1. 100 - 300 ml (Typically ~200mL for PML, 150 metalimnion and 75 – 100 for the hypolimnion) of lake water from each depth was filtered through 153 um mesh to remove large zooplankton. Water was then filtered through a precombusted 25mm GF/F filter (0.7 um pore size) at less than 200 mm Hg pressure. Filters were placed in drying oven at 60 C to dry for at least 48 hours. 20mL of filtered water was stored in a scintillation vial and acidified with 200uL of 2N H2SO4 for DOC analysis. Blank samples for POC and DOC were prepared with deionized water to control for contamination. All samples were sent to the Cary Institute of Ecosystem Studies for analysis.

Version Number
24

Cascade project at North Temperate Lakes LTER - High-resolution spatial analysis of CASCADE lakes during experimental nutrient enrichment 2015 - 2016

Abstract
This dataset contains high-resolution spatio-temporal water quality data from two experimental lakes during a whole-ecosystem experiment. Through gradual nutrient addition, we induced a cyanobacteria bloom in an experimental lake (Peter Lake) while leaving a nearby reference lake (Paul Lake) as a control. Peter and Paul Lakes (Gogebic county, MI USA), were sampled using the FLAMe platform (Crawford et al. 2015) multiple times during the summers of 2015 and 2016. In 2015 nutrient additions to Peter Lake began on 1 June, and ceased on 29 June, Paul Lake was left unmanipulated. In 2016 no nutrients were added to either lake. Measurements were taken using a YSI EXO2 probe and a Garmin echoMap 50s. Sensor- data were collected continuously at 1 Hz and linked via timestamp to create spatially explicit data for each lake.

Crawford, J. T., L. C. Loken, N. J. Casson, C. Smith, A. G. Stone, and L. A. Winslow. 2015. High-speed limnology: Using advanced sensors to investigate spatial variability in biogeochemistry and hydrology. Environmental Science & Technology 49:442–450.
Contact
Dataset ID
343
Date Range
-
Maintenance
complete
Methods
In two consecutive years, we measured lake-wide spatial patterning of cyanobacteria using the FLAMe platform (Crawford et al. 2015). To evaluate early warning indicators of a critical transition, in the first year we induced a cyanobacteria bloom through nutrient addition in an experimental lake while using a nearby unmanipulated lake as a reference ecosystem (Pace et al. 2017). During the second year, both lakes were left unmanipulated. Proposed detection methods for early warning indicators were compared between the manipulated and reference lakes to test for their ability to accurately detect statistical signals before the cyanobacteria bloom developed.
Peter and Paul Lakes are small, oligotrophic lakes (Peter: 2.5 ha, 6 m, 19.6 m and Paul: 1.7 ha, 3.9 m, 15 m, for surface area, mean, and max depth respectively) located in the Northern Highlands Lake District in the Upper Peninsula of Michigan, USA (89°32’ W, 46°13’ N). These lakes have similar physical and chemical properties and are connected via a culvert with Paul Lake being upstream. Both lakes stratify soon after ice-off and remain stratified usually into November (for extensive lake descriptions, see Carpenter and Kitchell, 1993).
In the first year, Peter Lake was fertilized daily starting on 1 June 2015 (DOY 152) with a nutrient addition of 20 mg N m-2 d-1 and 3 mg P m-2 d-1 (molar N:P of 15:1) through the addition of H3PO4 and NH4NO3 until 29 June (day of year, DOY 180). The decision to stop nutrient additions required meeting four predefined criteria based on temporal changes in phycocyanin and chlorophyll concentrations indicative of early warning behavior of a critical transition to a persistent cyanobacteria bloom state. (Pace et al. 2017). Nutrients uniformly mix within 1-2 days after fertilization based on prior studies (Cole and Pace 1998). No nutrient additions were made to Paul Lake. In the second year (2016), neither lake received nutrient additions.
We mapped the surface water characteristics of both experimental lakes to identify changes in the spatial dynamics of cyanobacteria. In 2015, mapping occurred weekly from 4 June to 15 August (11 sample weeks). In 2016, when neither lake was fertilized, the lakes were mapped three times in early to mid-summer. In both years, mapping occurred between the hours of 07:00 to 12:00 (before the daily nutrient addition). We rotated the order that we sampled the lakes to avoid potential biases due to differences in time of day. Each individual lake sampling event was completed in approximately one hour.
The FLAMe platform maps the spatial pattern of water characteristics. A boat-mounted sampling system continuously pumps surface water from the lake to a series of sensors while geo-referencing each measurement (complete description of the FLAMe platform in Crawford et al. 2015). For this study, the FLAMe was mounted on a small flat-bottomed boat propelled by an electric motor and was outfitted with a YSI EXO2™ multi-parameter sonde (YSI, Yellow Springs, OH, USA). We focused for this study on measures of phycocyanin (a pigment unique to cyanobacteria) and temperature. Phycocyanin florescence was measured using the optical EXO™ Total Algae PC Smart Sensor. The Total Algae PC Smart Sensor was calibrated with a rhodamine solution based on the manufacturer’s recommendations. Phycocyanin concentrations are reported as ug/L; however, these concentrations should be considered as relative because we did not calibrate the sensor to actual phycocyanin nor blue-green algae concentrations. Geographic positions were measured using a Garmin echoMAP™ 50s. Sensor- data were collected continuously at 1 Hz and linked via timestamp to create spatially explicit data for each lake. Each sampling produced approximately 3500 measurements in the manipulated lake and 2000 in the reference lake. The measurements were distributed by following a gridded pattern across the entire lake surface to characterize spatial patterns over the extent of the lake.
Version Number
15

Cascade Project at North Temperate Lakes LTER cross-lakes comparison carbon Data 1988 - 2007

Abstract
Data on dissolved organic and inorganic carbon as well as particulate organic matter and the partial pressure of CO2. Samples were collected with a Van Dorn bottle. Organic samples were collected from the epilimnion, metalimnion, and hypolimnion. Inorganic samples were collected at depths corresponding to 100%, 50%, 25%, 10%, 5%, and 1% of surface irradiance, as well as one sample from the hypolimnion. Samples for the partial pressure of CO2 were collected from two meters above the lake surface (air) and just below the lake surface (water).
Contact
Core Areas
Dataset ID
278
Date Range
-
Maintenance
completed
Metadata Provider
Methods
Field and laboratory protocols can be found in the Cascade Methods Manual, found here: http://c13.valuemembers.net/Pages/methods_09.htmlPOC DOC:A: To ash filters: 1. Place filters in a foil boat and cover. Put in 450 C oven for 2 hours. B: POCorPON 1. Place a 25mm ashed GForF filter into a filter holder (grid to grid) that is attached to an Erlenmeyer flask. 2. Pour 100 - 300 ml duplicate samples from each depth (PML, meta, hypo) through 153 um mesh to remove large zooplankton. (Typically ~200mL for PML, 150 meta, 75 - 100 hypo – check previous week and adjust as necessary) 3. Filter samples at less than 200 mm Hg pressure. Remove filters from towers, fold in half, and place two replicates in one labeled Petri dish. Be sure to indic ate volume of water filtered on the Petri dish and record it on the POC log . Place dish in drying oven with the cover on loosely . 4. After filters have dried (a couple of days ), remove dish from drying oven and store in desicc ator. Analyze samples at IES. 5. Each week, make 2 blank filters by filtering 200ml of DI and processing as above. C: DOC 1. Pour 20 mL of filtrate (from POC procedure) from each lake - depth into labeled , acid washed, glass scintillati on vial s and acidify with 200 uL 2N H 2 SO 4 . Prepare t wo replicate samples for each depth. Each week, make one blank sample using 20ml of DI (filtrate from POC blanks) and 200uL 2N H 2 SO 4 . Analyze samples at IES. D. COLOR 1. Fill a 60 mL HDPE bottle with GForF filtrate from each lake - depth (from POC proced ure). Store in refrigerator until it is convenient to analyze samples on a spectrophotometer. Let samples warm up to room temperature before running on spec. 2. Turn on spectrophotometer at let it warm up for 30 minutes. Set to 440 nm. After calibrating with distilled water, rinse cuvette with 10 mL of filtrate. Remove rinse, then fill with 30 mL of filtrate and measure absorbance. Continue in this manner until all samples have been measured. (See the more detailed instructions on using the GENESYS 2 s pectrophotometer at UNDERC in Spec Instructions.doc ). 3. To estimate the amount of machine drift, measure the absorbance of distilled water after measuring sample
NTL Keyword
Version Number
21

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

Cascade Project at North Temperate Lakes LTER: Zooplankton 1984 - 2007

Abstract
Zooplankton data from 1984-1995. Sampled approximately weekly with two net hauls through the water column (30 cm diameter net, 80 um mesh). There have been 5 zooplankton counters during this period, so species-level identifications (TAX, below) are not as consistent as those for some of the other datasets. To standardize across counters, I have assigned higher-level taxonomic categories for a few "confusing" taxa; these identifications can be found in the column LLTAX, below. Sampling Frequency: varies Number of sites: 5
Core Areas
Dataset ID
79
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
for counting details see: Christensen, D.L., S.R. Carpenter, K.L. Cottingham, S.E. Knight, J.P. LeBouton, D.E. Schindler, N. Voichick, J.J. Cole, and M.L. Pace. 1996. Pelagic responses to changes in dissolved organic carbon following division of a seepage lake. Limnology and Oceanography 41:553-559.
Short Name
CZOOP1
Version Number
5

Cascade Project at North Temperate Lakes LTER: Primary Production 1984 - 1990

Abstract
The Cascade project is a whole-ecosystem experimental test of the theory that: increased variance, red-shift of variance, and critical slowing down of recovery rate across components of a food web are leading indicators of a common type of regime shift in lake ecosystems caused by changes in the structure of the fish community.CASCADE Primary Production Dataset Sampling Frequency: varies Number of sites: 3
Core Areas
Dataset ID
72
Date Range
-
Maintenance
completed
Metadata Provider
Methods
14C-PRIMARY PRODUCTIVITYEQUIPMENT:Field:PPR float with line and clips for hanging bottles at selected depthsPPR field boxes containing:18, 60 mL reagent bottles wor glass stoppers, plus extra bottles and tops.2, 100-1000 microL automatic pipettor and several tipslab gloves and plastic apronplastic bag for used gloves and pipette tipsextra clips for hanging bottleswater pumpLab:6-tower vacuum filter apparatus4.7 cm Whatman GForF filtersScintillation vials with labeled caps (label includes lake, day, "D" or "L" for darkor light bottle, and depth, respectively. (e.g.: "L145 L1"; "W224 D6")REAGENTS:10 microCi 14C-bicarbonate (2 microCi mL-1)Dichlorophenol-dimethyl urea (DCMU) saturated solution0.1 N HCLScintillation fluor (Biosafe)PROCEDURE:(Observe safe radioisotope handling techniques at all times during this analysis!)A. In lab (morning, before going to the field)1. Transfer 14C from ampule to labeled scintillation vial with a disposablepipettor (under the fume hood). Put scintillation vial in the field box.2. Replenish supply of lab gloves, pipette tips, and DCMU in the field box.3. Remember to include the PPR float and the field boxes (check contentswith list) in the items loaded into the field vehicle(s).106B. In field1. Rinse and fill 3, 60 mL BOD bottles with water from each depth,corresponding to 100, 50, 25, 10, 5 and 1percent of surface irradiance. Avoidgetting air bubbles in bottles. TRY TO KEEP BOTTLES IN THE DARKAS MUCH AS POSSIBLE.2. Pipette 250 microL of water from each bottle (using the "14C pipettor").3. Pipette an additional 500 microL of water from the 6 dark bottles using the"DCMU pipettor" (the dark bottles are used as a t = 0 control).4. Using the "DCMU pipettor," add 500 microL DCMU to the dark bottles tokill the phytoplankton. (always done before 14C addition.) It isimportant not to contaminate "light" bottles with DCMU! Darkbottles are labeled, and are used only as dark bottles.5. Using the "14C pipettor," Pipette 250 microL of 14C into each of the 18 bottles,starting with the dark bottles to ensure there is enough isotope forcontrols.Summary of subtractions and additions:light bottles dark bottlesremove 250 microL 750 microL (250 plus 500)add DCMU - 500 microLadd 14C 250 microL 250 microL6. Replace stoppers and invert bottles 2 or 3 times to mix. Ensure thatstoppers are well-seated, so they don t come out. It often helps to twist thestopper as you push it into the bottle.7. Suspend bottles at appropriate depths for incubation. Record incubationstart time.8. AFTER 6 HRS: Remove bottles from water and place in carrying caseuntil ready to filter (filtering should be done promptly after removal ofbottles from water). Record incubation finish time. (Incubations usuallygo from ~9:30am-3:30pm)C. In lab (afternoon)1. Have readya. Flask used only for collecting 14C waste107b. Filter towers equipped with 4.7 cm GForF filters. Separate towersshould be used for light and dark (DCMU) bottles.c. Scintillation vials, with caps labeled for all samples.d. A full squirt bottle of 0.1 N HCl and a full squirt bottle of Milli-QTURN OFF THE LIGHTS - THE REST OF THE PROCEDURE SHOULD BEDONE IN DIM LIGHT!2. Prepare 3 totals:a. Add 10 mL scintillation solution (Biosafe) and 100 microL 1 N NaOHto 6 vials (label on cap should include lake, day, "TOT" ,anddepth id).b. Remove 250 microL from one of the light bottles from each depth andadd it to the proper vial. These vials are for calculating the totalamount of 14C added to the bottles.c. Tightly cap the total vials and put aside for later analysis with thescintillation counter3. Samples (process samples in the designated 14C fume hood):a. Empty the entire BOD bottle into the appropriate "light" or "dark"filter tower. Record volume if entire bottle is not filtered.b. Once the sample has filtered completely, rinse the bottle with asquirt of 0.1 N HCl, and filter this rinse. Then rinse the bottlewith water and filter this rinse. Rinse tower with 0.1N HCl, andthen finally with Milli-Q.c. Remove filter by folding it in quarters and place it at the bottom ofthe appropriate scintillation vial. Filter should be compact enoughin the bottom of the vial to be completely covered by thescintillation fluor (which fills half of the vial).d. Dry at 60-70degreeC for 24 hours.e. After drying filters, add 10 mL liquid scintillation solution to vialsand count in scintillation counter (see Scintillation CountingProcedure).D. Clean up:1081. When all samples have been filtered, squirt some acid down the last towerin the line to rinse. When the acid has been pumped out of the line, ventthe tower to expel all liquid. Lift towers to drain completely.2. Rinse BOD bottles and caps three times with hot tap water.3. Radioactive waste goes into a carboy marked and reserved for radioactivewaste. timestimesNOTEtimestimes The total radioactivity in each carboy must beknown; Record the date when 14C is initially put in the carboy and the datewhen the final amount of 14C is put in the carboy.4. Empty the remaining amount of 14C from the scintillation vial taken intothe field into the radioactive waste carboy. Discard the vial in the dryradioactive waste bag.5. Record the amount of radioactivity used in the isotope log book.CALCULATIONS:Use the SYSTAT command file CALCPPR.CMD to calculate primaryproductivity according to the following equation:mg Ctimesm-3timesh-1 =(CPMs - CPMb) times (VincorVfil) times (A) times (1.05)(DPMt) times (Eff) times (T)where:CPMs = counts per minute for sampleCPMb = counts per minute for DCMU controlVine = volume (mL) incubatedVeil = volume (mL) filteredA = total C in sample (in mg Corm3), calculated from sample alkalinity1.05 = isotope discrimination factorDPMt = disintegrations per minute of total amount of 14C added to each bottleEff = efficiency of scintillation fluor calculated from internalstandards for each sampleT = length of incubation (h)2. Use the method in Appendix III, along with measurements of solar radiationtimes andlight extinction from the weekly light profiles, to calculate daily production of thephotic zone and the mixed layer (see Carpenter et al., 1986).times see Pyranograph Method109REFERENCES:Carpenter, S.R., M.M Elser and J.J. Elser. 1986. Chlorophyll production, degradation,and sedimentation: Implications for paleolimnology. Limnol. Oceanogr. 31:112-124.Strickland, J.D.H., and T.R. Parsons. 1968. A practical handbook of seawater analysis.Bull. Fish. Res. Board Can. 167:267-279.Legendre, L., S. Demers, C.M. Yentsch, and C.S. Yentsch. 1983. The 14C method:Patterns of dark CO2 fixation and DCMU correction to replace the dark bottle.Limnol. Oceanogr. 28: 996-1003.
Short Name
CPRIM1
Version Number
5

Cascade Project at North Temperate Lakes LTER: Piscivore Fish 1984 - 2003

Abstract
Fish collected for the Casade Project. Sampling Frequency: varies Number of sites: 9
Core Areas
Dataset ID
86
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
FISH SAMPLING TECHNIQUESThe techniques used to sample the fish and estimate the population density in the cascadelakes, vary according to the species and life-stage of interest. The following techniquesfor the different fish populations have been used from 1984 to present, except whennoted.1. Minnows (Dace, Mudminnows, Sticklebacks and assorted small cyprinids) andBass (young-of-year):The gear most used to sample these small-bodied species is the minnow trap. Thetraps are commercially available under the name Gee s Minnow Trap. They aremade of 1or4" galvanized hardware cloth with approximately 1" openings in eitherend. The only modification made to the commercial trap, is treatment with acidprior to use to remove the shine of the new trap. Shiny traps have been found tobe less effective. Twenty-four minnow traps are set in the littoral zone and 18 inthe pelagic zone of each lake. The littoral traps are set from stakes approximatelyuniformly spaced around the lake at depths of .5 m and on the bottom alternately.The pelagic traps are set at 1 and 3 m across the deepest portion of the lake on asingle transect with 9 stations (one 1 m and one 3 m trap at each station). Thetraps are set bi-weekly for 24 hr. All fish are counted and identified to species.The traps are normally set unbaited. Bait (bread) is used when large numbers ofminnows must be caught, such as for a Delury estimate (Ricker, 1975).A subsample of approximately 400 individuals is measured. These 400 fish areanesthetized in small batches with MS-222. The anesthetized fish are placed on aclipboard covered with a sheet of transparency plastic. The nose of the minnow isplaced against a retaining board and a hole is punched in the plastic at the end ofthe minnow s tail. The distance from the edge of the plastic to hole is measuredback at the lab to obtain total length in millimeters.Both mark-recapture and Delury population estimation are used to estimate theabundance of minnows. With mark-recapture, a large subsample, greater than1000individuals, from a minnow-trap capture are finclipped and released. Minnowtraps are then reset after waiting at least 1 but not more than 7 days. Thepopulation is then estimated using the ratio of marked to unmarked fish caught inthe second set. The Delury estimate is done by depleting the population usingrepeated minnow trapping and recording the catch and cumulative catch. Theminnows are held in floating net boxes at densities of 1000-2000 per cubic meteruntil at least four trap sets have been made. The population is estimated by theintercept of the regression between catch and cumulative catch (the level ofcumulative catch where catch equals zero). The Delury and mark-recaptureestimates provides an independent population estimate to correlate the catch-per132unit-effort (CPUE) of the regular minnow-trapping with known populationdensities.1332) Bass and perch (age 1plus and older):The larger fishes are sampled for population estimation twice each year, once inmid-May and once in mid-August. The primary technique used is nightelectrofishing with mark-recapture population estimation.A 16 foot Cofelt electrofishing boat, with dual booms (3 4-ft electrodes perboom), is used. Electroshocking is done largely perpendicular to shore,shocking from approximately 3 meters water depth to the shore. DC current isused to minimize damage to the fish. 600 volts provides adequate current, 2-6amps, to stun the fish.All fish are placed in a live-well on board the shock boat and are taken to ashore station for processing. On shore, the first 25 fish of each species arestomach pumped for gut analysis. Scales are also taken from a subsample of thefish for age analysis. All fish are identified to species, counted, measured (totallength in millimeters), and weighed with either a Pesola spring-scale or anOhaus electronic pan balance. If the spring-scale is used then the fish is simplyheld by the lip with the clip on the scale; if the electronic scale is used the fish iswrapped in a wet cloth to restrain the fish and the fish and cloth are weighedtogether. The weight of the cloth is removed by taring the scale with the clothprior to weighing the fish.If a markorrecapture estimation of the population is to be done, all fish sampledon the first night of electrofishing are marked. The fish are tagged withindividually numbered anchor tags (Wydoski and Emery, 1983) if the fish isgreater than 150mm total length and has not been previously tagged. If the fishis smaller than 150mm, the dorsal lobe of the caudal fin is clipped. The markedfish are then placed in a holding net until the first sampling is complete. Thefish are released at the end of the first night of electrofishing. To increase thepower of the mark-recapture technique, the number of marked fish is increasedby angling and marking fish on the day prior to electroshocking at night forrecapture. The population is sampled again the following night to estimate theratio of marked to unmarked fish. For the Delury estimation, fish are removedfrom the lake using several days of sampling effort using both angling andelectroshocking.3) Scale Samples:Scale samples are taken at least once a year, from at least 50 randomly selectedfish of each species. Large fish are usually sampled for scales when they arecaught. At least 5 scales are taken from each fish from the area below the originof the dorsal fin and above the lateral line. Scales are permanently mounted ona plastic slide later for aging and individual growth determination (Summerfeltand Hall, 1987).1344) Larval Perch (and other pelagic larvae), 1989-present:Two techniques are used to sample pelagic fish larvae: purse seining, and sonar.a. Purse seining is a method of enclosing a volume of water in the pelagiczone with a net and filtering that water to obtain the larval fish. The netdesign and technique are described in Evans and Johannes (1988). Thenet used in the Cascade project is 33 meters long and 6 meters deep, madeof polyester net material with 1.6mm openings and dyed green.b. Sonar is used in conjunction with purse seining to obtain the sizefrequency,species composition, and spatial distribution of icthyoplankton.The Cascade project uses both 70 and 200 khz sonar. The transducer istowed approximately 20cm under the surface. The technique is outlined inThorne (1983). The HADAS acoustics processing hardware and softwareis used to analyze the recorded signal (see Rudstam, 1988, for adescription of the analysis).STATISTICAL POPULATION ESTIMATIONThe two techniques used in the Cascade project to estimate population density are themodified Peterson mark-recapture and Delury estimations (Ricker 1975).a. Mark-recapture is used for populations that are not being intentionallydepleted in a lake such as the bass population in Paul Lake.b. Delury estimates are used when a population is being removed from a lakesuch as for the bass in Peter Lake in the fall of 1989 or for minnows whichare easily handled.135REFERENCES:Evans, D.O. and P.R. Johannes. 1988. A bridle-less trawl and fine-mesh purse seine forsampling pelagic coregonine larvae with observations of the spatial distributionand abundance. Ontario Fish. Tech. Rep. no 27:1-19.Ricker, W.E. 1975. Computation and interpretation of biological statistics of fishpopulations. Department of the Environment, Fisheries and Marine Service,Fisheries Research Board of Canada Bulletin 191, Ottawa, Canada.Rudstam, Lars G. 1988. Patterns of zooplanktivory in a coastal area of the northernBaltic proper. Doctoral thesis at the University of Stockholm.Summerfelt, R.C. and G.E. Hall. 1987. Age and Growth of Fish. Iowa State UniversityPress, Ames. Iowa.Thorne, R.E. 1983. Hydroacoustics. pp. 239-260. In: L.A. Nielsen and D.L. Johnson ed.Fisheries Techniques. American Fisheries Society, Bethesda, Maryland.Wydoski, R. and L. Emery. 1983. Tagging and Marking. pp. 215-237. In: L.A. Nielsenand D.L. Johnson ed. Fisheries Techniques. American Fisheries Society,Bethesda, Maryland.136
Short Name
CPISC1
Version Number
5

Cascade Project at North Temperate Lakes LTER: Phytoplankton 1984 - 1995

Abstract
Data on epilimnetic phytoplankton from 1984-95, determined by light microscopy from pooled Van Dorn samples at 100percent, 50percent, and 25percent of surface irradiance. There have been 4 counters during this period, with the same counter from 1991-95. Standardization among counters is difficult, so I recommend sticking to the 1991-95 data if possible. Cottingham (1996) describes the counting protocols in detail. Sampling Frequency: varies Number of sites: 5
Core Areas
Dataset ID
80
Date Range
-
LTER Keywords
Maintenance
completed
Metadata Provider
Methods
See for detail: Cottingham, K.L., and S.E. Knight. 1995. Effects of grazer size on the response of mesotrophic lakes to experimental enrichment. Water Science and Technology 32(4): 157-163.
Short Name
CPHYT1
Version Number
3

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
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