PHYSICAL CONTROLS ON THE DEVELOPMENT AND CHARACTERISTICS OF ANTARCTICSEA-ICE BIOLOGICAL COMMUNITIES - A REVIEW AND SYNTHESIS

Ice structures found in Antarctic sea ice and related morphological pr ocesses are summarized, including: frazil ice growth; the flooded snow layer; pressure ridge induced flooding; thermally driven brine draina ge; and platelet-ice formation. The associated colonization, physiolog ical adaptation, and growth of sea ice biota within these structures, to the levels presently identifiable, are also reviewed. A strong inte raction exists between the physical processes that form, evolve and de teriorate sea ice, and the biological communities located within sea i ce. Variability of ice structure and associated biological communities over small spatial scales necessitated analysis of the biological com ponent in combination with physical and chemical properties of the sea ice. The ice microstructure provides indications of the growth and ev olution of the ice properties and initially defines how ice biota colo nize the ice. The light, temperature,space and nutrient fields within which ice biota subsequently adapt and grow, are the other key determi nants of the biology. While the ice microstructure shapes the localize d biological response; relatively large regions of pack ice have chara cteristic microstructures. Regional patterns of biomass and biological productivity within the Antarctic sea ice zone may therefore be predi ctable as a result of these physical-biological associations. Examples from the drifting pack ice and fast ice zones of the Weddell and Ross Seas are given.