Aquatic Sciences Meeting, Albuquerque 2001

SS08 Processes at the Benthic Interface (Environmental Connections)

Date: Tuesday, February 13, 2001, Time: 11:45:00 AM

Location: Ruidoso/Pecos

MacIntyre, H, L, University of Maryland, Cambridge, USA, macintyr@hpl.umces.edu

MODELING THE EFFECT OF SEDIMENT STABILIZATION BY MICROPHYTOBENTHOS ON SYSTEM-LEVEL PRODUCTIVITY DURING RESUSPENSION

Primary production in subtidal benthos is very sensitive to the clarity of the overlying water. Because microphytobenthos can stabilize the sediment fabric, an abundant population of benthic microalgae can in theory enhance their productivity by inhibiting resuspension in a positive feedback cycle. Experiments conducted in a microcosm with “farmed” assemblages of microphytobenthos confirmed that the amount of sediment resuspended at a given friction velocity declined as the density of microphytobenthos increased. However, the fraction of the microphytobenthos that was resuspended also declined with increasing population density. A spectrally-resolved model of productivity in the water column and sediment was based on these data. It predicted that production by cells released into the water column offset the loss in “true” benthic production with increasing resuspension when the density of microphytobenthos was low but not when the density was high. As a result, predicted system-level production increased with friction velocity at low densities and decreased at high densities. While the response of “true” benthic production is consistent with a positive feedback model, the production dynamics of the resuspended population are not.

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Aquatic Sciences Meeting, Albuquerque 2001

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