Hutchins 9802132 The Subantarctic Zone of the Southern Ocean plays a critical role in both past and present global climate change, and is therefore of considerable interest to the international science community. This proposal seeks funds to support a unique collaboration with Australian marine scientists to investigate biogeochemical cycling in this oceanic region. The prinicipal investigator, Professor David Hutchins of the College of Marine Studies of the University of Delaware, in collaboration with Dr. Giacomo Di Tullio of the Department of Geology, University of Charleston, and Australian counterpart, Dr. Peter N. Sedwick, of the Cooperative Research Center for the Antarctic and Southern Ocean Environment, University of Tasmania, will conduct an interdisciplinary study of the physiological status and response of the whole microbial community to growth limitation by iron and major nutrients. Experiments will examine the possibility that iron may control Si:N utilization ratios by the biotas (including implications for species dominance), heterotrophic/autotrophic competition for iron, and iron and major nutrient effects on production of the radiatively important gas dimethylsulfide (DMS) and its precursor DMSP. The field program and research cruise on the Australian vessel RSV Aurora Australis will involve Australian, New Zealand, and French researchers as well as the American researchers supported under this project. Results will contribute to our understanding of factors affecting global carbon cycling, and will further the exchange of ideas and encourage cooperation between the marine science communities of the United States, New Zealand, France, and Australia.
