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BENTHIC NUTRIENT FLUX IN A SMALL ESTUARY IN NORTHWESTERNFLORIDA (USA)
Citation:
Didonato, G T., E M. Lores, M C. Murrell, AND L M. Smith. BENTHIC NUTRIENT FLUX IN A SMALL ESTUARY IN NORTHWESTERNFLORIDA (USA). GULF AND CARIBBEAN RESEARCH. Gulf Coast Research Laboratory, Ocean Springs, MS, 18:15-25, (2006).
Impact/Purpose:
To measure benthic nutrient fluxes in Escambia Bay during a severe drought
Description:
Benthic Nutrient Flux in a Small Estuary in Northwestern Florida(USA).Gulf and Caribbean Research 18, 15-25, 2006.
Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2-+NO3-), phosphate (PO4-), and dissolved silica (DSi) were measured in Escambia Bay, an estuary within the larger Pensacola Bay system of northwestern Florida (USA). Our study occurred during a severe drought which reduced riverine inputs to Escambia Bay. Laboratory incubations of field-collected cores were conducted on 8 dates between June and October 2000 to estimate nutrient flux, and cores were collected from locations exhibiting a range of sediment organic matter content. NH4+ flux ranged from 110.4 to -48.1?mol m-2h-1, but the average flux was 14.6 ?mol m-2h-1. Dissolved silica (DSi) fluxes were also highly variable (145.3 to -109.3 ?mol m-2h-1), but the average net flux (9.3 ?mol m-2h-1) was from the sediment to the water column. Bay sediments were neither a strong source nor sink for NO2-+NO3- or PO4- during this period. Low NH4+ fluxes were similar to published estimates from lagoonal Gulf of Mexico (GOM) estuaries, possibly due to the reduced freshwater input. Diminished regeneration of phosphate relative to inorganic nitrogen observed during the study period was consistent with previous research in Pensacola Bay suggesting phytoplankton phosphorus limitation. The estimated residence time of Escambia Bay and the mean turnover times for NH4+ and NO2-+NO3- suggested that benthic flux significantly enhanced nitrogen concentrations in overlying water. Furthermore, calculations showed that sediments provided a majority of the dissolved inorganic nitrogen (65%) and phosphorus (60%) to the bay relative to inputs from the Escambia River (the main freshwater source) during this period of reduced freshwater input.