WINTER DISTRIBUTION AND OVERWINTERING STRATEGIES OF THE ANTARCTIC COPEPOD SPECIES CALANOIDES-ACUTUS, RHINCALANUS-GIGAS AND CALANUS-PROPINQUUS (CRUSTACEA, CALANOIDA) IN THE WEDDELL SEA

During the Winter Weddell Gyre Study in September-October 1989, the ho rizontal and vertical distribution, stage composition and feeding cond ition of the three antarctic copepod species Calanoides acutus, Rhinca lanus gigas and Calanus propinquus were studied. The data indicate tha t C. acutus and R. gigas have the bases of their distributional ranges (sensu Makarov et al. 1982) in the Antarctic Circumpolar Current (ACC ) and in the Warm Deep Water (WDW) entering the Weddell Gyre (WG). C. propinquus lived mainly in the cold WG south of the ACC. C. acutus ove rwintered mainly in the WG as stage IV copepodites (C). The species ma inly inhabited the layers below the T(max)degrees stratum and down to 2000 m, but C V and females occurred slightly higher than C III and IV . Males prevailed over females and were confined to a rather narrow la yer between 500 and 1000 m. Feeding experiments suggested all deep-liv ing stages to be resting. However, if this species spawns in late autu mn the younger C I-II can stay in the Winter Water (WW). R. gigas inha bited mainly the T(max)degrees stratum. In the eastern part of the WG, R. gigas breed in the WDW in autumn and hibernate as C I-III and C V- VI in the first and second winter, respectively. In the ACC zone, howe ver, its life cycle is different and winter breeding of overwintered a dults occurs. Most of the C. propinquus population overwintered in the WG as C III-V, inhabiting the WW. In the upper water layers in the in terior of the WG, C III dominated with upto 18,000 individuals 1,000 m 3. Shallow living C. propinquus were in the active, feeding state. Per sistence of active feeding zooplankton populations in the WW of the WG can be an important factor influencing processes of phytoplankton dev elopment and the particle flux.