Microbial Cycling of Dissolved Organic Phosphorus in the Oligotrophic North Atlantic: The Nucleic Acid Connection

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Despite a major focus on nitrogen as the limiting nutrient in marine ecosystems, there is evidence that in some marine environments, especially the vast oligotrophic central gyres, that phosphate appears to be refractory and potentially limiting, although a fraction of the phosphate pool does appear to turn over rapidly. Dissolved nucleic acids will be examined as a model component of this rapidly-cycling fraction, because many of the breakdown rates and the concentrations of the resulting intermediates can be measured. These parameters will be measured by a combination of fluorometric, isotopic, and spectrophotometric techniques and will be compared to parallel measurement of the major phosphate pools and fluxes. This project will test the hypotheses that microbial breakdown of dissolved nucleic acids is both: 1) a quantitatively important pathway, and 2) a model pathway for the cycling of labile dissolved organic phosphate in the oligotrophic North Atlantic. This research will further our understanding of the cycling of dissolved organic phosphate, a suite of compounds with potentially global importance to marine primary production. Furthermore, this research will lead to insights into microbial processes of biopolymer and monomer breakdown. Finally, since dissolved nucleic acids are genetic material and also significant reservoirs of dissolved organic carbon and nitrogen, these studies will increase our knowledge of environmental gene transfer and of dissolved organic carbon and nitrogen cycling in the environment.