SGER: Offshore mobilization of aged floodplain organic matter in response to Hurricane Katrina

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PetschEAR-0555047The proposed research seeks to examine the uptake of aged, floodplain organic matter (OM) into near- and offshore sediment microbial communities following the remobilization and offshore delivery of floodplain deposits in response to Hurricane Katrina, which made landfall on Aug. 29, 2005 just west of the Mississippi birdsfoot delta, with a storm surge impacting a large area of OM-rich marshlands. This sediment mobilization may lead to excursions in organic carbon and nitrogen accumulation rates, biological oxygen demand, and nutrient regeneration. The project will collect sediment cores from Breton and Chandeleur Sounds, examining the concentration and composition of OM in nearshore and offshore sediments deposited before and after passage of Katrina, examining the distribution and isotopic composition (13C, 14C) of phospholipids isolated from pre- and post-Katrina sediments, and through description of the microbial communities in Katrina-associated sediments as revealed by phospholipid profiles and DNA-based community assays.Broader ImpactsResults will promote understanding of the impact of storm events on stochasticperturbations of the short-term carbon cycle. The investigation will be coordinated with parallel research pursued by Miguel Goni and colleagues on samples collected west of the delta. This combined coverage of OM mobilization associated with Katrina along a substantial length of the Louisiana coast will contribute to estimates of OM reworking and reburial fluxes, net heterotrophy, O2 demand and CO2 release linked to OM degradation.Samples collected will be employed as teaching tools in a Sedimentary Geochemistry course taught by the PI, and execution of the project will contribute to the professional development of the Co-PI, a post-doctoral scientist beginning to establish her research career.