Chemical and Microbiological Characterization of Phytoplankton Decay

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This research is designed to determine fundamental information on the stability of specific algal biomarkers in the water column. Research questions include: 1) how do various chemical classes change qualitatively and quantitatively over time; 2) what is the time frame for alteration of specific compounds as well as chemically defined classes of organic matter and 3) What is the role of microbial processes in mediating the changes by attacking specific pools of phytoplankton carbon. This project is an integrated, multidisciplinary approach aimed at predicting the fate of photosynthetically produced organic matter in the marine water column. Carefully controlled laboratory studies are tracking the changes in chemical composition of algal remains (as distinct lipids, pigments, carbohydrates and amino acids) mediated by the microbial community. Measurements of bacterial biomass, production and metabolism are being conducted in tandem to provide degradation rates for specific relevant compounds. Ongoing experiments with unialgal cultures have been extended to include a dinoflagellate, currently receiving considerable attention as a major producer of organic carbon in coastal marine systems. Results with unialgal communities will be compared to mixtures of laboratory cultures and field collected communities whose composition can be predicted and verified. The research tests the hypothesis that the decay of highly labile species control the degradative rates for a mixed community through enhanced microbial metabolism.