Aquatic Sciences Meeting, Albuquerque 2001

CS04 Benthic-Pelagic Coupling: Seasonality, Pulses, and Flux

Date: Thursday, February 15, 2001, Time: 3:00:00 PM

Location: Mesilla

Wetz, M, S, Belle W. Baruch Institute for Marine Biology and Coastal Research, University of South Carolina , Georgetown, USA, mwetz@belle.baruch.sc.edu

Hayes, K, C, South Carolina Department of Health and Environmental Control and Baruch Institute (USC), Georgetown, USA, khayes@belle.baruch.sc.edu

Lewitus, A, J, Baruch Institute (USC) and South Carolina Department of Natural Resources, Georgetown, USA, lewitus@belle.baruch.sc.edu

GRAZING CONTROL OF PHYTOPLANKTON COMMUNITIES IN A SALT MARSH ESTUARY. 2. IMPACT OF OYSTERS

Oyster reefs can influence phytoplankton biomass through grazing and nutrient release. However, in situ studies testing the influence of oysters on phytoplankton community structure are lacking. Using a free flow design, we sampled water masses as they moved through two small tidal creeks in North Inlet, South Carolina, an estuary with dense aggregates of oysters (Crassostrea virginica). The creeks were similar in size and hydrography, but one creek had all live oysters removed as part of a large field manipulation study, while the other had intact oyster reefs. Samples were collected over a complete tidal cycle on five dates from July-September 2000, and phytoplankton community composition at the mouth and back (60 m) of the creeks determined using microscopy and the CHEMTAX factorization program to relate HPLC pigment profiles to phytoplankton composition. In both creeks, phytoplankton biomass (chl a) was 1.25- to 2.0-fold higher on the flooding tide, but the presence of oyster reefs affected phytoplankton composition and reduced phytoplankton biomass over the tidal cycle, supporting the influential role of oyster reefs in shaping microbial food web structure and function.

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Aquatic Sciences Meeting, Albuquerque 2001

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