Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Wednesday, February 14, 2001, Time: 10:15:00 AM

Location: Ruidoso/Pecos

Craig, N, I, Department of Biology,University of South Florida, Tampa, USA, ncraig@chuma1.cas.usf.edu

Thomas, F, I, Department of Biology, University of South Florida, Tampa, USA, fthomas@chuma1.cas.usf.edu

HYDRODYNAMIC CONTROL ON POREWATER NUTRIENT DYNAMICS IN A MIXED CARBONATE SHOAL COMMUNITY

Nutrient concentrations, (nitrogen and phophorus species), were measured in near- bottom waters and the porewaters of a carbonate shoal supporting a mixed seagrass, coral and macroalgal community in the Florida Keys. Overlying water velocities at this site ranged from 0 to 2 cm/s at slack high and low tides to an average of 35 cm/s during flooding and ebbing tides. Because hyfordynamics affect nutrient flux across the sediment-water interface in permeable sediments, it is expected that vertical profiles of porewater nutrients will correlate to tidal current velocity. During periods of low flow, nutrients may accumulate in porewaters due to mineralization of organic matter and a relatively slow rate of exchange across the sediment-water interface. However, as current velocity increases, a rapid efflux of nutrients out of sediments may occur, thereby decreasing concentration gradients in porewater nutrient profiles. This hydrodynamically driven flushing of the sediment may serve as a source of nutrients to the local algal community.

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Aquatic Sciences Meeting, Albuquerque 2001

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