Calanus finmarchicus stages abundance from 200um vertical ring nets TimeSeries stations from R/V Gulf Challenger in the Gulf of Maine; Wilkinson Basin and Jeffreys Ledge, 2012-2013 (GoM_Calanus_2012-2013 project)

Version: working
Version Date: 2015-01-14

» RAPID: Effect of a Very Low NAO Event on the Abundance of the Lipid-Rich Planktonic Copepod, Calanus finmarchicus, in the Gulf of Maine (GoM_Calanus_2012-2013)
Runge, Jeffrey A.University of MaineChief Scientist, Principal Investigator
Thompson, CameronGulf of Maine Research Institute (GMRI)Contact
Allison, DickyWoods Hole Oceanographic Institution (WHOI BCO-DMO)BCO-DMO Data Manager

Dataset Description

Abundance of Calanus finmarchicus stages caught in 200um vertical ring nets(bottom to surface) at two time series stations in the Gulf of Maine (2012 - 2013).

Users are requested to consult with Jeffrey Runge prior to preparation of any manuscripts or reports, either written or online, that make use of zooplankton and hydrographic data originating from this study. The data are freely available without need for consultation with Dr. Runge after October, 2017.

Methods & Sampling

These deployments followed the AZMP protocols (Mitchell et al. 2002). Using a 0.75 meter diameter SEA-GEAR Model 9600 twin-ring, 200µm mesh net, two vertical casts were made to within 5 meters of the bottom at each station.  

Two replicate samples from separate casts were preserved in a 4% seawater-buffered formaldehyde solution. In the laboratory, all formalin preserved zooplankton samples were split in half using a Folsom Plankton Splitter. Half of the sample was archived for identification and enumeration of zooplankton, and the other half was processed for biomass determination. To estimate abundances the archival split was diluted and sub-sampled with a 5 mL Stempel pipette. Depending on abundance in the sample, multiple subsamples were taken until a target number of 75-150 C. finmarchicus copepodids were enumerated and staged and in addition at least 200 specimens in total were counted and identified to the lowest possible taxa.

Mitchell, M. R., G. Harrison, K. Pauley, A. Gagné, G. Maillet, and P. Strain. (2002) Atlantic Zonal Monitoring Program Sampling Protocol. Canadian Technical Report of Hydrography and Ocean Sciences 223.


Data Processing Description

The counts were normalized to abundance (number m-2), taking into account the subsample dilution, the split, and volume sampled by the net at the station. Because of unreliable flowmeter readings, we calculated volume filtered by the net from net area and net depth. The filtered volume calculated geometrically, as we have done here, is closely related to the flowmeter volume when flowmeters were working properly.

Volume = Net Depth * Net Area

Abundance (number m-2) = ( (count*Dilution Factor / Archival split) / Volume) *Station Depth

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Data Files

(Comma Separated Values (.csv), 4.45 KB)
Primary data file for dataset ID 544850

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cruiseeach deployment has its own cruise ID following this format: GC for R/V Gulf Challenger; followed by the date (mmddyy) text
stationWB-5 or WB-7 text
siteeither Jeffreys Ledge (WB-5) or Wilkinson Basin (WB-7) text
latlatitude decimal degrees; North is positive
lonlongitude decimal degrees; West is negative
date_localdate local time mmddyyyy
month_localmonth local time mm
day_localday local time dd
yearyear yyyy
depth_netdepth of the ring net according to length of wire out of the winch; as read by a meter wheel meters
depth_stationwater depth at the station according to depth sounder on vessel meters
num_idednumber of Calanus finmarchicus (including nauplii) that were counted and staged during analysis of the sample integer
dil_factorwater volume the sample is diluted into / volume of water subsampled number
naupliiabundance of all naupliear stages in water column; note that the 200um mesh would let many young stages through number per m2
stage_CIabundance of copepodid stage 1 number per m2
stage_CIIabundance of copepodid stage 2 number per m2
stage_CIIIabundance of copepodid stage 3 number per m2
stage_CIVabundance of copepodid stage 4 number per m2
stage_CVabundance of copepodid stage 5; pre-adult stage number per m2
femaleabundance of females(copepodid stage 6) in water column number per m2
maleabundance of males (copepodid stage 6) number per m2
yrday_localday of year local time number

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Dataset-specific Instrument Name
Ring Net
Generic Instrument Name
Ring Net
Dataset-specific Description
0.75 meter diameter, SEA-GEAR Model 9600 twin-ring, 200um mesh net
Generic Instrument Description
A Ring Net is a generic plankton net, made by attaching a net of any mesh size to a metal ring of any diameter. There are 1 meter, .75 meter, .25 meter and .5 meter nets that are used regularly. The most common zooplankton ring net is 1 meter in diameter and of mesh size .333mm, also known as a 'meter net' (see Meter Net).

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R/V Gulf Challenger
Start Date
End Date
This deployment is a collection of 17 one-day cruises to two stations in the Gulf of Maine between April 6, 2012 to May 21, 2013.

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Project Information

RAPID: Effect of a Very Low NAO Event on the Abundance of the Lipid-Rich Planktonic Copepod, Calanus finmarchicus, in the Gulf of Maine (GoM_Calanus_2012-2013)

Coverage: Gulf of Maine: Wilkinson Basin and Jeffrey's Ledge

"The copepod, Calanus finmarchicus, is a dominant member of the plankton in the Gulf of Maine, (GoM), despite its location at the southern edge of the species' subarctic range. Wilkinson Basin, one of the three deep basins in the GoM, harbors very high concentrations of the early developmental stages of C. finmarchicus in the summer through winter and serves as a source of C. finmarchicus to GoM coastal ledges and banks. A recent study based on C. finmarchicus habitat characteristics across the North Atlantic predicts that climate-driven change will force the distribution of C. finmarchicus northward out of the GoM over the next several decades. However, the oceanographic and life history responses of C. finmarchicus to environmental variability in the Gulf are complex and largely unknown. The research in this RAPID proposal takes advantage of a rare opportunity to test a hypothesis about the control of C. finmarchicus abundance in the GoM from climate change related external forcing. The hypothesis states that a distinctly lower C. finmarchicus abundance follows, with a two-year lag, the occurrence of a very negative North Atlantic Oscillation (NAO). The specific processes that causally connect low C. finmarchicus with the NAO are not known. The research here tests the prediction that C. finmarchicus abundance will be very low in Wilkinson Basin in 2012, two years after one of the most negative NAOs on record, dating back to the 1860?s. Field observations in the form of a time series of measurements of hydrography, food availability and C. finmarchicus stage abundance will be taken at a fixed station in Wilkinson Basin and in the Maine coastal region, supported by measurements taken on the Scotian Shelf. A research survey, coordinated with a scheduled cruise in the Gulf of Maine in September, 2012, will take additional collections in Wilkinson Basin and throughout the GoM. Frozen and ethanol preserved samples of C. finmarchicus will also be collected for population genetic studies. The abundance results will be compared with historical time series and survey data collected over the past two decades, confirming or refuting the expectation of extreme NAO influence on GoM C. finmarchicus populations." (from the Award abstract)

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Funding SourceAward
NSF Division of Ocean Sciences (NSF OCE)

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