Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Wednesday, February 14, 2001, Time: 12:15:00 PM

Location: Aztec

Lumsden, S, E, Texas A&M University, College Station, TX, USA, Beth@ocean.tamu.edu

Burd, A, B, Texas A&M University, College Station, TX, Mexico, aburd@ocean.tamu.edu

Ornolfsdottir, E, B, Texas A&M University, College Station, TX, USA, erla@ocean.tamu.edu

Pinckney, J, L, Texas A&M University, College Station, TX, USA, pinckney@ocean.tamu.edu

Effects of Zooplankton Community Structure on Trophodynamics in Dilution Bioassays: Experimental Results

Galveston Bay, Texas, is a shallow, turbid estuary with limited tidal flushing and frequent sediment resuspension by wind events and commercial fisheries. Small water volume relative to the benthic surface area, high turbidity, and low irradiance restrict benthic primary productivity leaving the water column dynamics of fundamental importance. The zooplankton and phytoplankton communities in Galveston bay are a dynamic and changing species assemblage. Understanding how this assemblage functions is pivotal to interpreting ecosystem trophodynamics. Dilution bioassays were used to discern the seasonal grazing relationships for Galveston Bay. This bioassay approach estimates grazing impacts of zooplankton and growth rates of phytoplankton by reducing the encounter rate between predators and their prey. HPLC techniques were used to identify and quantify the phytoplankton functional groups while zooplankton were enumerated by direct microscopy. Quantified knowledge of both the predator and prey composition result in a more comprehensive evaluation mechanism for assessing short term grazer impacts. Results suggest that the diverse zooplankton community found in a sub-tropical estuary such as Galveston Bay, and possibly similar estuaries, may result in fundamentally different responses in dilution bioassays.

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Aquatic Sciences Meeting, Albuquerque 2001

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