Aquatic Sciences Meeting, Albuquerque 2001

PC03 Undergraduate Education

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Schaaf, J, A, Center for Great Lakes Studies REU, Milwaukee, USA, jas31@axe.humboldt.edu

MacKenzie, R, A, Center for Great Lakes Studies , Milwaukee, USA, ram@uwm.edu

QUANTIFYING THE EFFECTS OF ZEBRA MUSSELS ON BENTHIC MACROINVERTEBRATES OF NEARSHORE LAKE MICHIGAN AND ELKHART LAKE, WI

The invasion of the zebra mussel (Dreissena polymorpha) could have major implications on benthic ecology in the Laurentian Great Lakes. Quantitative descriptions of interactions between zebra mussels and other organisms are required. Of particular interest is how benthic macroinvertebrates respond to the presence of this exotic species. A field study was done to quantify effects on benthic communities in nearshore Lake Michigan compared to an inland kettle lake (Elkhart Lake WI). Tile samplers with and without zebra mussels were deployed: presence of mussels increased algal biomass as chlorophyll a (2-3X); benthic organic matter (2-3X); and benthic macroinvertebrate abundance and diversity (3-4X) after correction for increased colonizable shell substrate. No macroinvertebrate taxon decreased in population density. A significant finding was the presence of Echinogammarus ischnus, an exotic amphipod only recently documented in southern Lake Michigan. Data suggests that zebra mussels are redirecting energy from the water column to the benthos. This appears to be beneficial to benthic communities but could have serious consequences for other components of the Great Lakes food chain.

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Aquatic Sciences Meeting, Albuquerque 2001

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