CS39B Zooplankton - Community Dynamics
Date: Wednesday, June 12, 2002
Time: 10:15:00 AM
Location: Sidney
 
LonsdaleDJ, State University of New York, Stony Brook, NY, USA, dlonsdale@notes.cc.sunysb.edu
Caron, D, A, University of Southern California, Los Angeles, CA, USA, dcaron@usc.edu
Cerrato, R, M, State University of New York, Stony Brook, NY, USA, rcerrato@notes.cc.sunysb.edu
 
ZOOPLANKTON CHANGES ASSOCIATED WITH THE INTRODUCTION OF HARD CLAMS (MERCENARIA MERCENARIA) INTO MESOCOSMS
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We have demonstrated that the presence of hard clams in mesocosms (300 L) can prevent the phytoplankton community from shifting to dominance by the harmful alga Aureococcus anophagefferens (brown tide). This result is likely due in large part to the direct grazing impacts of these benthic suspension feeders. Hard clam feeding, however, was also related to changes in microzooplankton community structure. At the termination of an experiment (8-10 days), mesocosms containing clams also had reduced copepod abundance but increased ciliate abundance compared to controls. We speculate that the reduction in copepod abundance was due to hard clam predation on some copepod eggs (Acartia) and nauplii which, in turn, released ciliates and increased their grazing pressure on brown tide (cell size ~ 2.4 mm in diameter). The population growth rate of ciliates may also have been improved in tanks with clams due to the absence of brown tide. Our results suggest that to better understand the role of benthic suspension feeders in phytoplankton dynamics, one should also consider their affects on the zooplankton community.