Iron-dependent metabolic processes are central to nutrient uptake and energy transduction. For open ocean phytoplankton, restricted iron availability may control the patterns and magnitude of primary productivity in surface waters. This research will determine the iron use efficiencies for several ecologically important phytoplankton species. The work will originally focus on a strain of Synechococcus. Iron-limited continuous cultures will be used to obtain cells adapted to several iron-controlled growth rate. Dr. Rueter will measure the total iron content and the distribution of the iron into several well characterized proteins that may control energy and nitrogen metabolism in these cells. The work with Synechococcus will lead to comparative studies with several other species, followed by direct competition experiments in iron-limited growth conditions. This work will provide an understanding of the role of iron in phytoplankton metabolism in a parallel framework to that used by other investigators studying the efficiency of light and nitrogen metabolism. The efficient use of iron by individual phytoplankton species is controlled by their strategies of regulation. These strategies effect protein content and efficiency of growth processes and not only have competitive significance for those species but also help shape the community structure of surface water ecosystems.
