SEASONAL OCCURRENCE OF PLANKTIC CRUSTACEA IN SEDIMENT TRAP SAMPLES AT3 DEPTH HORIZONS IN THE GREENLAND SEA

Zooplankton were quantitatively investigated in sediment trap samples deployed in the Greenland Sea at three locations (72 degrees 00.7'N, 7 degrees 02.5'W, 72 degrees 23.0'N, 7 degrees 42.7'W and 72 degrees 22 .9'N, 7 degrees 42.7'W). Overall samples covered a period of three ann ual cycles (July 1989 to July 1992). The investigation of zooplankton, consisting almost exclusively of Crustacea (> 99%), shows that the ma jority of the species must be regarded as ''swimmers'', which actively invaded the traps. Crustacea were composed of 45 species, mainly Cope poda, Amphipoda and Ostracoda. Each depth level showed a characteristi c species composition. Diversity decreased with depth. The samples wer e dominated by Copepoda in terms of abundance and by Amphipoda with re spect to biomass. The seasonal occurrence of Crustacea showed a maximu m during winter and a minimum during summer. Carnivores were regularly found in the collected material, indicating that they had been active ly attracted by the organic matter emanating from the traps. Omnivores showed a distinct seasonal occurrence. During winter, when primary pr oduction is low, omnivores change to a predatory way of life and they were consequently also found in increasing numbers. Herbivores were al ways rare. Due to the high number of ''swimmers'' found in winter, whe n particle flux is at its minimum, particle flux measurements may be s everely biased at this time of the year.