COI Funded Project: A Collaborative Microbiological and Organic Geochemical Study of Dissolved Organic Carbon Cycling in the Coastal Ocean


Research Funded: 2004

Proposed Research

Massive amounts of dissolved organic carbon (DOC) are transported by rivers toward the sea each year, but very little of this material actually survives the transit through the coastal zone into the open ocean.   The microbiological and organic geochemical mechanisms behind the disappearance of this terrestrially-derived DOC are still largely unknown and this problem represents a critical gap in our understanding of the global carbon cycle.   Adding to this mystery is the longstanding view that terrestrially-derived DOC is resistant to microbial degradation, but recent work has shown the cycling of this material to be much more dynamic than previously thought.   In estuaries there are sharp gradients in the chemical composition of DOC as well as large shifts in the community structure of heterotrophic bacteria, the key agents in DOC degradation.   In this proposed study, we seek to apply new experimental and conceptual tools in organic geochemistry and microbial ecology to gain a better understanding of the connections between DOC cycling and microbial dynamics in the Plum Island estuary in northeast Massachusetts.   In a matrix of carefully controlled experiments, we will apply a suite of spectroscopic, chromatographic and natural-isotope-tracing techniques to track the degradation of terrestrially-derived DOC.   In conjunction with these measurements, we will also apply the latest DNA-based molecular technologies to identify shifts in bacterial community structure.   All of these observations will be scrutinized within a framework of similar observations obtained from the estuarine environment.   We anticipate the results of this study will not only provide a platform from which to launch a larger, externally-funded project, but will also advance our knowledge of the specific microbiological sinks of terrestrially-derived DOC in coastal environments.