There are four specific objectives to this research program which, together, will yield answers to important questions regarding indigenous marine viruses which infect phytoplankton. First, the investigator will characterize the host specificity of viruses that have been isolated and which infect eukaryotic and prokaryotic phytoplankton. Each of the viral isolates will be screened against a large number of potential hosts with close and distant phylogenetic relationships, to the original host. Second, the temporal variability of a virus which infects Synechococcus sp. will be determined monthly in natural waters by plaque assay. Third, Dr. Suttle will determine the decay rates (turnover times) in natural waters of three viruses which have been isolated and developed plaque assays for. Fourth, the effect of natural virus communities on phytoplankton productivity and community structure will be ascertained. Almost nothing is known about viruses which infect marine phytoplankton; yet, data included in this proposal suggests that viruses are important and can affect rates of carbon fixation. This research will answer fundamental questions concerning phytoplankton-virus interactions and persistence of infectious viruses in the sea. Only studies such as these will provide the requisite data to enable incorporation of viral-mediated processes into comprehensive models of nutrient and energy cycling in the global oceans.
