Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

1984

Journal

Bulletin of Marine Science

Volume

35

Issue

3

First Page

601

Last Page

614

Abstract

We have developed a lagrangian computer simulation model to investigate the interactions between dissolved and particulate carbon-substrates of detrital (vascular plants) and phytoplankton origin, microbes attached and free-living in the water column, and consumers of these substrates for a specific estuarine water body: the Duplin River, Sapelo Island, Georgia. Model simulation experiments were directed toward investigating the potential for both carbon resource and heterotrophic grazing as controls on free-living and particle-attached bacterial densities. Given available information from the literature and our own work, we present simulations of the model that approximate what one generally finds in this estuary during summer relative to the dynamics of particulate organic carbon (paC), dissolved organic carbon (DOC), free-living bacteria and microconsumers. Predicted dynamics of the bacteria were insensitive to macroconsumer grazing but highly sensitive to the parameter values governing microconsumer grazing rates and metabolism. Within reasonable constraints of the parameter values used, however, we were unable to reduce the predicted densities of particle-attached bacteria by manipulation of either resource (carbon) availability or grazing pressures. We propose several alternate hypotheses that might explain this discrepancy between model results and what is generally reported for natural systems.

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