This award supports Dr. Joseph J. Torres of the University of South Florida for collaborative research in marine biology with Dr. A. V. Aarset of the University of Trondheim, Norway. They are interested in the metabolic adaptations of organisms that live under sea-ice in the Polar regions. Such adaptations include strictly regulating the concentration of bodily fluids, tolerating dilution of bodily fluids, or some form of compromise between the two. Dr. Torres will determine metabolic energy costs for individual amphipods at different experimental salinities using oxygen electrodes and water-jacketed respirometers in multiple configuration. Dr. Aarset will examine survivorship and hemolymph concentration of these amphipods in response to changing salinity. He will also evaluate their tolerance of supercooling. This research will be done at Ny Aalesund, a field station on Spitsbergen, as part of the Pro Mare Program of Norway. Polar sea-ice is a conspicuous and important feature of the world's oceans. A well developed but little studied community of organisms exists within and beneath this ice. Gammarid amphipods are the most important macrofaunal grazers there, and they form a potentially important trophic link between the ice algae and the fishes living in the water column below the pack ice. These small crustaceans must withstand severe salinity changes caused by seasonal freezing and thawing of the pack ice. The proposed research will produce an excellent analysis of the adaptive strategies used by several species of amphipods.