Oceanographic profile Zooplankton biomass measurements collected using net in the Antarctic during 1989 (NCEI Accession 0000971)

Composition of the metazoan plankton was studied during R.V. Dmitry Mendeleev cruise 43 (February to April, 1989) in the Atlantic sector of the Southern Ocean. Samples were collected from ten stations at six locations. Four of the locations were in open oceanic waters along the 15 degree W longitude. Two others were in the Bransfield Strait and in inshore waters near Elephant Island. At three locations at 15 degrees W sampling was conducted twice or thrice. At all stations three different sampling gears were used to collect different size groups of zooplankton: series hauls were performed by 200 l water-bottle, mesoplankton net and macroplankton trawl for depths from 200 m to the surface. The average biomass of zooplankton in open oceanic waters was 20.55 gm-2 wet weight. Copepoda Calanoida dominate composing 54.8% of the total plankton, followed by Euphausiacea (19.8%), Ctenophora (9.7%) and Copepoda Cyclopoida (7.2%). Biomass of any other taxonomic group was less than 1 gm-2. The relative biomass of Calanoida had a tendency to decrease southward along 15 degrees W from 86.1 to 68.1% in February and from 81.8 to 23.6% in March-April. The relative biomass of Euphausiacea increased in the same manner from 2.3 to 17.8% in February and from 3.7 to 41.6% in March-April. The average biomass of calanoids from February to March-April decreased from 77.3 to 31.2% and that of euphausiids increased from 6.2 to 33.8%. The contribution of copepods and euphausiids to the production of the plankton community in the Antarctic is discussed.