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Aquatic Microbial Ecology

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AME 21:187-194 (2000)  -  doi:10.3354/ame021187

Effects of the zebra mussel on nitrogen dynamics and the microbial community at the sediment-water interface

Peter J. Lavrentyev1,*, Wayne S. Gardner2,**, Longyuan Yang3

1University of Michigan, Cooperative Institute for Limnology and Ecosystem Research, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109, USA
2National Oceanographic Atmospheric Administration, Great Lakes Environmental Research Laboratory, 2205 Commonwealth Boulevard, Ann Arbor, Michigan 48105, USA
3Chinese Academy of Sciences, Nanjing Institute of Geography and Limnology, 73 East Beijing Road, Nanjing, Jiangsu 21008, PR China
Present addresses: *University of Akron, Department of Biology, Akron, Ohio 44325-3908, USA. E-mail: **University of Texas at Austin, Marine Science Institute, 750 Channel View Drive, Port Aransas, Texas 78373, USA

ABSTRACT: A flow-through experiment was conducted on intact cores of sediments from Saginaw Bay, Lake Huron, to examine how trophic interactions between filter-feeding bivalve mussels and microbial populations could affect nitrogen dynamics at the sediment-water interface. The zebra mussels used in this experiment removed a large proportion of protozoa and phytoplankton from the overlying water, particularly heterotrophic nanoplankton (up to 82%), while bacterial populations showed less change. A 3-fold decrease in the protozoan to bacterial carbon ratio corresponded to a 2.5-fold increase in relative ammonium removal rates as estimated from the dark loss of 15N-ammonium. Excretion by the bivalves also increased net ammonium flux to the water, thus elevating the total calculated areal ammonium removal rates to about 6-fold over rates observed in the control treatment. These data suggest that filter-feeding bivalves may significantly affect nitrogen transformation rates near the sediment-water interface by excreting ammonium and altering the microbial food web structure at the sediment-water interface.

KEY WORDS: Nitrogen · Microbial food web · Sediment-water interface · Bivalve mussels

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