The distribution and biodiversity of algae was assessed to enable possible future predictions of the effects of global warming. Sites (5 in the first season, 4 in the second) were established around the Cape Hallett peninsula and samples of algae were collected from the ice at regular intervals. As far as possible these sites represented the range of conditions of sea ice in the region. CTD probes ... measured chlorophyll concentration, temperature and salinity. Algae samples were collected from ice samples, water samples (collected from 5, 25 and 50m depths) and from the sea floor and were used to determine chlorophyll concentration using fluorometry, for carbon and nitrogen concentrations, DNA content, MAA composition, biodiversity and cell numbers (algae and bacteria). PAM and PEA were used to assess photosynthetic capacity of algae extracted from the sea ice. This method was used to determine the response of the algal community to experimentally induced changes in salinity, temperature and light levels. Molecular biological techniques were used to characterise the prokaryotic community in the sea ice and in the water beneath the ice.