Viruses in Pack Ice Communities of the Ross Sea, Antarctica

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Abstract P.I. Marcia Gowing OPP97-25136 Viruses in Pack Ice Communities of the Ross Sea, Antarctica Primary productivity of sea ice algal communities in the Southern Ocean is significant. In lower latitudes, processes such as grazing and lysis by viruses are thought to control algal populations, but there are few data on grazing within ice communities and no data on viruses of ice algae. Ice communities should be excellent sites for studying viral control of populations of eukaryotic algae and protozoans because populations can reach high densitites and many habitats are nearly closed for parts of the year. This study will use transmission electron microscopy (TEM) of individual eukaryotic algal and protozoan cells and light microscopy and TEM of water samples to assess viral infections and viral populations in a variety of pack ice communities from the Ross Sea. The objectives are (1) to determine the extent of the occurrence of viruses within cells of algae and protozoans in ice communities and to estimate the percentage of infected cells, (2) to relate the extent of the occurrence of viruses within cells to the stages of succession of sea ice communities (3) to assess the potential for ice communities to seed viruses to the pelagial, (4) to determine the extent of ingestion of virus- like particles by sea ice protozooplankton, (5) to compare these features of ice communities to those of phytoplankton and protozooplankton assemblages in the seawater directly under the ice and (6) to describe and quantify the size structure of the free virus-like particles in the intersitital water of ice communities and in the seawater directly under the ice. Thus study will contribute to the understanding of sea ice community ecology and will allow incorporation of viruses of eukaryotic algae and protozoans into models of carbon flow for the Antarctic.