The overwintering strategy of Antarctic krill (Euphausia superba DANA) under the coastal fast ice off the Ongul Islands in Lutzow-Holm Bay, Antarctica

During the BIOMASS study of the SIBEX (1984/85), some aspects of overwintering strategies of Antarctic krill (Euphausia superba DANA) were studied in the Kita-no-ura Cove (69°00′N, 39°35′E) off the East Ongul Island in Lutzow-Holm Bay. Krill were collected monthly with a light trap from May through early November 1984. Krill under the coastal fast ice survive the food deficient Antarctic winter principally by the following strategies : (1) changing their habitat from the pelagic to the benthopelagic during the dark period to subsist on detritus on the sea bed, (2) lowering their oxygen consumption rate down to the level of 0.27ml/g dry wt/h. They show positive phototaxis, swim actively in the darkness, and probably extend their food retention time in the gut in late fall and early winter. Their C and N composition, C : N ratio and fatness are supposed to be mainly effected by the change in metabolic rate and reflect their nutritional condition. The difference in metabolic dynamics of krill between fall and winter to early spring period was recognized through the seasonal change in C and N composition