The Seagrass History of Florida Bay Reconstructed from Integrating Micropaleontological and Geochemical Proxies

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ABSTRACTThe Seagrass History of Florida Bay Reconstructed from Integrating Micropaleontological and Geochemical ProxiesLaurel S. Collins, Rudolf Jaffe, James W. Fourqurean, William T. AndersonFlorida International UniversityHow much of the variation in coastal environmental conditions is naturally occurring and how much has been caused by humans? This question is addressed with the historical record of seagrass abundance, which today is highly correlated with environmental water quality. The study is set in Florida Bay, part of the environmentally challenged Everglades National Park. The main objective is to collect cores of Florida Bay sediment and use proxies of seagrass abundance contained therein as indicators of the environmental water quality for the past few hundred years. Proxies are used because seagrass itself is not preserved in sediments. The geochemical proxies are measures of organic matter (organic carbon, nitrogen, molecular biomarkers, stable isotopes - d13C, d15N, dD) and micropaleontological proxies are abundances of seagrass indicator species (foraminifera, diatoms). Hypersalinity has recently been linked to large seagrass die-offs in Florida Bay. Several proxies will also be used to determine the correlation between historical salinity and seagrass changes. This grant funds the pilot project to extract sediment cores from Florida Bay, conduct sedimentologic analyses, determine radiometric ages, and calibrate the proxies to modern seagrass abundances and salinities. The investigators will subsequently collect geochemical and micropaleontological data from the cores, integrate the data in statistical analyses, and interpret the results. Knowledge is advanced by incorporating the results in geology, biology and chemistry classes taught by the investigators, and providing the basis for three graduate student theses. FIU is a federally recognized minority university.