Benthic Exchange of C, N, and P Along the Estuarine Ecotone of Lower Taylor Slough, Florida (USA): Effect of Seasonal Flows and Phosphorus Availability
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The southern Everglades and Florida Bay have experienced a nearly 50 % reduction in freshwater flow resulting in increased salinity and landward expansion of mangrove forest. Given the marine end-member is a natural source of P to this region, it is necessary to understand the interactions between inflows and P availability in controlling the exchange of materials across the mangrove ecotone. From 2007 to 2008, we used sediment core incubations to quantify fluxes of dissolved inorganic N and P and dissolved organic carbon (DOC) in three ecotone areas (dwarf mangrove, pond, and bay). Experiments were repeated seasonally over 2 years involving P-enriched surface water as a factor. We saw consistent uptake of soluble reactive P (SRP), DOC, and nitrate + nitrite (N+N) by the soils/sediments and release of ammonium (NH4 +) from soils/sediments to the water column across all sites and seasons. P enrichment had no discernible effect on DIN or DOC flux, suggesting that rapid P uptake may have been more geochemically mediated. However, uptake of added P occurred across all sites and seasons, reflecting high uptake capacity in this carbonate system and the potential of the mangrove ecotone to sequester P as it becomes more available.
KeywordsEverglades Nutrient flux Peat soil Sediment Phosphorus Nitrogen Carbon Mangrove Seagrass Nutrient addition
We would like to acknowledge a NOAA CSCOR grant (NA06NOS4780098) to Texas A&M University that provided much of the funding for this research. Support for this work was provided by Everglades National Park, the Southeast Environmental Research Center, the Florida Coastal Everglades Long-Term Ecological Research program (National Science Foundation cooperative agreements #DEB-1237517 and DBI-0620409), the Everglades Foundation and the South Florida Water Management District. We thank Drs. V. Rivera-Monroy and E. Castañeda-Moya for their valuable insights throughout this project, two anonymous reviewers for their helpful comments and recommendations, and G. Losada for field support. This is contribution number 609 from the Southeast Environmental Research Center at Florida International University.
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