Aquatic Sciences Meeting, Albuquerque 2001

CS37 Zooplankton

Date: Wednesday, February 14, 2001, Time: 10:30:00 AM

Location: Aztec

Kovalcik, P, A, The University of Akron, Akron, USA, pakoval@uakron.edu

Lavrentyev, P, J, The University of Akron, Akron, USA, peter3@uakron.edu

Bundy, M, H, Estuarine Res. Ctr. Acad. Natural Sci., St. Leonard, USA, Bundy@acnatsci.org

Vanderploeg, H, A, NOAA Great Lakes Environ. Res. Lab, Ann Arbor, USA, vanderploeg@glerl.noaa.gov

Hersha, D, K, The University of Akron, Akron, USA, hersha@uakron.edu

MICROZOOPLANKTON FUEL COPEPOD PRODUCTION DURING THE WINTER-SPRING TRANSITION IN LAKE MICHIGAN

Microzooplankton abundance, growth, and trophic interactions with planktonic copepods were examined in a series of shipboard experiments in Lake Michigan during winter and early spring of 1998-2000 as part of the Episodic Events Great Lakes Experiment (www.glerl.noaa.gov/eegle). Microzooplankton biomass (1.9-44.6 ug C/l) exhibited significant spatial and temporal variations, especially in coastal waters, and was close to (or even exceeded) mesozooplankton biomass. Under low ambient temperatures (1-4 C), the microzooplankton community (composed primarily of oligotrichs and heterotrophic dinoflagellates) grew at the rates of 0.1 to 0.5d, and surprisingly, the growth rates of specific ciliate taxa exceeded 1.0 d. Two of the dominant calanoid species, Diaptomus sicilis and Limnocalanus macrurus, showed distinct feeding preferences for different microzooplankton. On the average, microzooplankton comprised 44 and 67% of their experimentally measured carbon uptake, respectively. Combined with data showing enhanced microbial food web activity (Hersha et al. this meeting), these results suggest that microzooplankton are an abundant and potentially critical component of the winter-spring plankton community in large temperate lakes as over-wintering copepods begin their reproductive cycles.

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Aquatic Sciences Meeting, Albuquerque 2001

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