9300474 Conley This three-year award supports U.S.- Sweden cooperative research in marine ecology between Daniel J. Conley of the University of Maryland's Center for Environmental and Estuarine Studies and Fredrik Wulff of the Department of Systems Ecology, Stockholm University. The objective of the research is to determine the processes controlling the net exchange of nutrients from sediments of the Baltic Sea. Using theoretical analyses, field and laboratory experimental studies and model verifications, the investigators will work together on determining biogeochemical control mechanisms in varying geographical areas of the Baltic Sea. Annual cruises are planned with researchers from Sweden, Poland and Russia. Biogeochemical cycles and processes in a marine system are of prime concern for local coastal zone and shallow seas. The Baltic Sea offers excellent opportunities to study these processes since it is a well-defined and intensively studied estuary that has experienced large-scale environmental changes from eutrophication and human activity. Both eutrophying substances and toxic substances (nitrogen and phosphorus) are increasing in the Baltic, which in turn give rise to storage of silica in the sediments and low levels of dissolved silicate. These low levels may have future consequences on species composition and the food web. In order to reverse the current trends in eutrophication, not only found in the Baltic Sea, but also in other estuaries, the investigators will take sediment cores from the study sites and characterize them in terms of their physico-chemical features, and the flux rates for silicate, dissolved nitrogen species, and phosphorus. These data will be used to develop a process oriented model describing the exchanges of nutrients. The research will complement and enhance the present data and advance understanding of the mechanism underlying changes in the Baltic Sea. Dr. Conley brings to this collaboration expertise in the bi ogeochemical cycling of silica. This is complemented by the Swedish investigator's expertise in biogeochemical modeling of fluxes of nitrogen, phosphorus and silica between water and sediments. ***
