This investigation is a continuation of research into the mechanisms used by hydrothermal vent animals to nurture themselves and to avoid the toxic potentials of the vent habitats. The on-site studies will be executed on cruises to 13'N on the East Pacific Rise during 1991 and 1992 in cooperation with a French group from IFREMER. The studies will focus on measuring the rates of exchange of CO2, O2, sulfide and potential nitrogen sources by the intact chemoautotrophic symbiotic associations (vestimentiferan tubeworms and mussels) under different conditions of temperature, pH, O2, sulfide and CO2, to define the environmental requirements and limitations on these organisms as well as to investigate the interaction of animal and symbiont metabolism in dealing with sulfide and its oxidation products. The transport of CO2, O2 and reduced sulfur compounds within the animals will be examined by means of experiments with intact animals and with isolated O2 and sulfide binding proteins. Similar studies will also be carried out on the hydrothermal vent crabs to gain an understanding of their abilities to live continuously in low O2, high sulfide environments. Similar studies will additionally be conducted for comparison on non-vent symbiotic and heterotrophic species as well.
