Collaborative Research: Carbonate Dissolution in Shallow Water Tropical Sediments: The Role of Seagrasses

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ABSTRACTOCE-0136037Recently, it has been suggested that oxygen transport into sediments via the roots and rhizomes of seagrasses might resolve the observed discrepancy between the amount of carbonate dissolved and the amount of acid produced from remineralization of sediment organic matter. Combining field observations, laboratory experiments and modeling analysis, a PI from Old Dominion University will team up with a PI from San Jose State University to quantify the influence of seagrass productivity on carbon flux and carbonate dissolution in shallow waters of Lee Stocking Island, Bahamas, a tropical system. The PIs will compare the sediment and porewater composition recovered from a variety of sample types (bare ooid sands to densely vegetates regions with 70% seagrass cover) to establish the relationship between carbonate dissolution in sediments and seagrass density. Other studies to be carried out include incubation experiments of individual seagrass shoots to determine the amount of O2 generated by the roots and rhizomes under variable light and porewater O2 conditions. Additionally, whole sediment core incubation experiments will determine the rate of sediment organic matter degradation and carbonate dissolution. Lastly, Drs. Burdige and Zimmerman plan to compare their data with those obtained via a model of diagenetic processes in carbonate sediments. Results from this study will not only provide basic information on ecological and biogeochemical processes in tropical systems, but will help constrain budgets for carbonate cycling in shallow water carbonate bank environments.