Pease, T. K. Skidaway Institute of Oceanography, tamara@skio.peachnet.edu
Hee, C. K. Univeristy of North Carolina, Chapel Hill, chee@marine.unc.edu
Alperin, M. University of North Carolina, Chapel Hill, alperin@marine.unc.edu
Martens, C. University of North Carolina, Chapel Hill, martens@marine.unc.edu

 
BIOGEOCHEMICAL EFFECTS ON PHYTOPLANKTON AND SEAGRASS CARBON REMINERALIZATION: A LABORATORY DEGRADATION EXPERIMENT
 
Two important factors controlling sedimentary carbon degradation are the quality of the organic input and the microbial system into which the organic matter is deposited. In order to quantify these effects, a laboratory degradation experiment was conducted in which coastal sediment was amended with phytoplankton or seagrass and was incubated under sulfate reducing or methanogenic conditions. Organic carbon (OC) consumption and production in the major carbon pools were traced by measuring concentrations of particulate organic carbon (POC), total dissolved organic carbon (DOC), acetate, dissolved inorganic carbon (DIC), and methane. In addition, stable carbon isotope ratios of the POC, DOC and end products were analyzed. Although initial rates of POC degradation were rapid for all treatments, seagrass carbon was much more resistant to degradation than phytoplankton carbon. Approximately 50% of the phytoplankton carbon was remineralized by the end of the experiment, while only 10% of the seagrass carbon was remineralized. Additionally, sulfate reducing communities were more effective at degrading the POC than the methanogenic communities. For example, in the phytoplankton treatments, 31% of the added POC remained at the end of the experiment as compared to 45% in the methanogenic treatments.
 
Day: Tuesday, Feb. 2
Time: 11:45 - 12:00pm
Location: Eldorado Hotel
 
Code: SS32TU1145E