Data Contributed By:
Kendra L. Daly
College of Marine Science
University of South Florida
140 Seventh Ave. S.
St. Petersburg, FL 33701
Phone: 727-553-1041
E-Mail: kdaly@marine.usf.edu
Net sample collections: Meng Zhou, Yiwu Zhu, Ryan Dorland, Dan Mertes, and Joe Smith
Sample Analyses: Jason Zimmerman, Alexander Timonin, Tatjana Semenova
Cruises:
Laurence M. Gould, 23 April - 6 June 2001 (LMG0104 cruise report), 18 net tows
Laurence M Gould, 7 April - 21 May 2002 (LMG0203 cruise report), 16 net tows
Methods
Zooplankton abundance, vertical and horizontal distribution, and population structure were assessed using a 1 m2 Multiple Opening and Closing Nets and Environmental Sampling System (MOCNESS) with nine nets having 333 µm mesh and environmental sensors of temperature, salinity and depth. The entire water column was sampled on the downcast using net # 0, which was not analyzed. The upper water column was typically sampled using nets 1 and 2 from 500 m to 200 m at 150 m depth intervals, nets 3 and 4 from 200 m to 100 m at 50 m depth intervals, and nets 5 to 8 from 100 m to the surface at 25 m depth intervals. Some tows were deployed down to 1000 m, and some tows were towed targeting krill swarms at irregular depths. Approximate locations of process study stations are shown in Fig. 1. More precise locations of the casts in Fig. 2.
Zooplankton samples were immediately preserved in 10% buffered formalin solution. All the large organisms (>15 mm) in the sample were removed and identified to taxa. The sample was then split to about 100 individuals of euphausiids. All euphausiids in the split were identified to species and life history stage and measured for length to the nearest 0.5 mm for larvae and to the nearest 1.0 mm for juvenile and adults. Next the sample was split to about 100 individuals of copepods. Copepods were identified to species and life history stage (female, male, copepodite V, or other copepodite). All other zooplankton in the split were identified to taxa and counted. For the Euchaetidae, we followed the designation of Park (1994) who ascribed the Antarctic species to the genus Paraeuchaeta. This data object ("krill") reports the abundance of each euphausiid species by life stage and size class. The companion data object "zooabund" reports the counts of zooplankton per subsample/split by taxa and life stage or size class.
Greenwich Mean Time was local time + 4 hours.
Reference:
Park, T. 1994. Taxonomy and distribution of the marine calanoid copepod family Euchaetidae. Bulletin of the Scripps Institution of Oceanography University of California, San Diego v. 29, University of California Press, Berkeley, CA, 203 pp.
Fig. 1. Approximate locations of process cruise stations in Marguerite Bay during austral autumn 2001 and 2002.
Fig. 2. Locations of MOCNESS stations for LMGould-0104 (2001) and LMGould-0203 (2002) cruises. Numbers correspond to the cast number.
Notes on Volume Filtered values:
The 1 m2 MOCNESS net volume filtered data were corrected for the following net tows:
The flowmeter used to calculate the volume of water filtered did not work for the tows shown below; the data shown in the listings for those tows are therefore derived, not measured. Using the net distance and the average angle of the net, the volume filtered was estimated. These estimates have about a 10% error or higher when currents were present.
