Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Wednesday, February 14, 2001, Time: 10:45:00 AM

Location: Ruidoso/Pecos

Koch, E, W, Horn Point Lab, University of Maryland Center for Environmental Science, Cambridge, MD, USA, koch@hpl.umces.edu

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

SEAGRASS-INDUCED SOLUTE FLUXES BETWEEN THE WATER COLUMN AND PERMEABLE SEDIMENTS

The hydrodynamical obstacle individual seagrass shoots present to flowing water, induces pressure gradients that cause the penetration of water several centimeters into the sediment upstream and downstream of the shoot. In order to keep mass balance, porewater is released into the water column in a confined area immediately downstream of the shoot. Similar processes are also observed for individual seagrass shoots within low to medium density canopies. In contrast, very dense seagrass canopies (1870 shoots/m2) act as single obstacles, i.e. penetration of water occurs in front of the canopy (down to 4 cm) and porewater is released behind the canopy. The different pattern observed for individual shoots within low/medium- and high-density canopies is attributed to the attenuation of current velocity by the plants. As the seagrass shoot density increases, water flow within the vegetation decreases and, therefore, seagrass-induced solute fluxes between the sediment and the water column also decrease. Seagrasses colonizing permeable sediments, thus, irrigate the surrounding sediments. This process has the potential to affect the geochemistry of vegetated sediments as well as plant growth.

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Aquatic Sciences Meeting, Albuquerque 2001

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