Studies on the Physiological Ecology of Hydrothermal Vent Chemoautotrophic Symbioses

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9301374 CHILDRESS The animals associated with deep-sea hydrothermal vents represent an ancient fauna of global distribution within the oceans. The very existence of these communities depends upon the ability of a few invertebrate/bacterial symbiotic associations to oxidize the reduced chemical species (sulfide or methane) from the hydrothermal vents using oxidants (such as oxygen or nitrate) from the surrounding deep-sea water to power primary production in this environment. The capacity for interaction of the symbiotic association with the chemical properties of the vent environments is fundamental to the primary production which supports these ecosystems. The central objective of this project is the determination of the importance of the concentration of carbon dioxide (PCO2) as an environmental factor affecting the rates of primary production by hydrothermal vent chemoautotrophic symbioses. This project is composed of there components, each with its own objectives: 1. A survey of diverse vent and seep environments to determine the extent to which chemoautotrophic symbioses in these habitats are exposed to elevated carbon dioxide and have high concentrations of carbon dioxide in their bodies. 2. Shipboard studies of the physiology supporting primary productivity in symbiotic vent animals in order to evaluate whether the concentration of carbon dioxided is a variable which limits primary production by the symbiotic associations. 3. The observation and measurement of temporal changes at a station located at 13oN in order to describe the niches of the symbioses over long time scales to assess long term rates of primary productivity in these environments. This project will greatly increase our understanding of the nature of the interactions between the vent animals and their chemical environment, in particular the interactions with pH and inorganic carbon, contributing to our understanding of the functioning of the vent and other chemoautotrophic ally supported ecosystems. ***