Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Wednesday, February 14, 2001, Time: 10:30:00 AM

Location: Ruidoso/Pecos

Huettel, M, H, Max Planck Institute for Marine Microbiology, Bremen, Germany, mhuettel@mpi-bremen.de

Rusch, A, , Max Planck Institute for Marine Microbiology, Bremen, Germany, arusch@mpi-bremen.de

PARTICLE FILTRATION, BENTHIC RESPIRATION AND NUTRIENT REGENERATION IN INTERTIDAL SANDS

With a series of field experiments in an intertidal sand flat we demonstrate the effects of advective sediment-water coupling for organic matter decomposition in permeable sediment. Three sediment layers could be distinguished with respect to their organic matter inventories: 1) a surface layer with strong physical mixing and decreased bacteria and organic particle concentrations, 2) an intermediate layer affected by advective pore water flows with high concentrations in labile matter and microorganisms, and 3) the diffusion-dominated sediment below, where organic matter was mostly refractory and bacterial numbers low. During immersion, water filtered through the sand fueled the sediment with organic matter and electron acceptors, resulting in increased sedimentary decomposition and oxygen fluxes up to 120 mmol/m2/d. During emersion, nutrients built up in the upper sediment layers, promoting growth of benthic diatoms. These strong tidal changes in the sedimentary environment were superimposed by seasonal changes, indicating dominance of degradation and hydrodynamic removal of organic material during autumn/winter and fresh POM input throughout spring and summer. We discuss the consequences of the short- and long-term temporal changes in the sedimentary biogeochemical environment.

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Aquatic Sciences Meeting, Albuquerque 2001

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