Aquatic Sciences Meeting, Albuquerque 2001

CS40 Nutrients, Primary Production, and Aquatic Ecosystems

Date: Wednesday, February 14, 2001, Time: 2:30:00 PM

Location: La Cienega

Sin, Y, , Coastal Ecology Branch, U.S. EPA, Newport, Oregon, USA, sin.yongsik@epa.gov

Wetzel, R, L, College of William and Mary, School of Marine Science/Virginia Institute of Marine Science, Gloucester Pt., USA, dick@vims.edu

BOTTOM-UP VS. TOP-DOWN CONTROLS ON THE DYNAMICS OF ESTUARINE PHYTOPLANKTON: A CASE STUDY OF THE YORK RIVER ESTUARY, VIRGINIA (USA)

The relative importance of top-down vs. bottom-up controls on phytoplankton dynamics was investigated in a river-dominated estuarine system by a combination of extensive long-term data analyses, field studies and ecosystem modeling analyses. Results from the analyses of spatially and temporally extensive data suggested that phytoplankton may be controlled by bottom-up control (resources limitation). This scenario is supported by field observations made over an annual cycle at three stations in the channel of the estuary. An ecosystem model was used to verify the scenario and the results of modeling analyses supported the importance of bottom-up control especially hydrodynamic processes on phytoplankton dynamics in the York River estuary. The results of this study suggest that phytoplankton dynamics are controlled by bottom-up rather than by top-down controls (zooplankton grazing).

This Session Listing

Aquatic Sciences Meeting, Albuquerque 2001

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