A neuston net with a 1-m wide by 0.3-m high mouth and 0.333-mm mesh was utilized for collection of all zooplankton samples. A General Oceanics flowmeter was attached in the mouth of the net in order to estimate the volume of water filtered during each tow. The net was towed out of the ship's wake for five minutes at approximately two knots (3.7 km/h). Upon retrieval, the net was hosed down and contents of the cod end were transferred to a sample jar. Large jellyfish and flotsam were rinsed off with seawater to remove any attached plankton and discarded at sea. The sample was preserved with formalin in ambient seawater to make a 5% formalin solution.
U.S. GLOBEC Northeast Pacific California Current System Mesoscale Process Studies
\nNeuston Data
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Contacts for this data set are:
\nDr. Richard Brodeur
\nNorthwest Fisheries Science Center
\nNational Oceanographic and Atmospheric Administration
\nNewport, OR 97365
\nPhone: 541-867-0336
\nEmail: rick.brodeur@noaa.gov
\n
Suzan Pool
\nCooperative Institute of Marine Resources
\nOregon State University
\nNewport, OR 97365
\nPhone: 541-867-0195
\nEmail: suzan.pool@noaa.gov
\n
During juvenile salmonid trawling cruises, additional sampling included CTD profiles, neuston net tows, and chlorophyll a water samples. At most stations, data on all parameters were collected.
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Results:
\nDetailed analyses of the neuston community are presented in Reese et al. (2005) and Pool and Brodeur (2005).
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References:
\nBrodeur, 1991
\nPool and Brodeur, 2005
\nReese et al., 2005
\nSchabetsberger et al.,\u00a0 2003
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Last modified: February 24, 2004
In the laboratory, the samples were washed over a 0.320-mm mesh sieve with tap water to remove formalin, then transferred to water. Additional extraneous contents were subsequently removed. To obtain displacement volumes, samples were allowed to settle overnight in Imhoff settling cones or graduated cylinders depending on the sample volume. Biovolumes (ml per 100 m3) were calculated from displacement volumes and flowmeter readings.
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Sample was transferred to a clear Pyrex dish on a white background for sorting and removing zooplankton .5 mm using a lighted magnifying glass. This size fraction was chosen based on prey size selected by juvenile coho and Chinook salmon in previous trophic analyses (Brodeur, 1991; Schabetsberger et al., 2003). Occasionally, large samples with many macrozooplankton were subsampled with a Folsom plankton splitter and the counts estimated. The macrozooplankton were enumerated and identified to the lowest practical taxon using a dissecting microscope. Life stages of the specimens were determined when possible. Completed samples were transferred to 70% ethanol. Counts were standardized into concentrations expressed as numbers per 100 m3.