Aquatic Sciences Meeting, Albuquerque 2001

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

Date: Thursday, February 15, 2001, Time: 2:45:00 PM

Location: Mesilla

Hayes, K, C, University of South carolina / Baruch Institute, Charleston, USA, khayes@belle.baruch.sc.edu

Wetz, M, S, University of South carolina / Baruch Institute, Georgetown, USA, mwetz@belle.baruch.sc.edu

Lewitus, A, J, University of South carolina / Baruch Institute and SCDNR-MRRI, Charleston, USA, lewitus@belle.baruch.sc.edu

GRAZING CONTROL ON PHYTOPLANKTON COMMUNITIES IN A SALT MARSH ESTUARY. 1. IMPACTS OF MICROZOOPLANKTON

In North Inlet, a high salinity salt marsh estuary near Georgetown, South Carolina, oysters and microzooplankton can exert pronounced controls on phytoplankton population growth through grazing and nutrient regeneration. However, information is lacking on the relative influences of these processes on phytoplankton biomass or community composition, and the dependency of grazing pressure on tidal stage. We determined phytoplankton growth rates, microzooplankton grazing rates, degree of nutrient limitation and ammonium regeneration rates by the dilution technique in two creeks of proportional area, one containing oysters and one with oysters removed. Samples were collected at three tidal stages on five dates from July-September 2000. We also determined the effect of microzooplankton grazing on phytoplankton community composition by analyzing HPLC pigment profiles with the CHEMTAX modeling program. The impacts of nutrient limitation and microzooplankton grazing on phytoplankton communities varied with nutrient loading patterns, with apparent phytoplankton growth rates greater than microzooplankton grazing rates during drought periods and higher grazing after rain events. The relative influence of oyster grazing on phytoplankton during this same period was further examined by Wetz et al. (companion talk).

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Aquatic Sciences Meeting, Albuquerque 2001

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