Gardner, W.S., J.F. Cavaletto, T.H. Johengen, J.R. Johnson, R.T. Heath, and J.B. Cotner, Jr., 1995.  Effects of the Zebra Mussel, Dreissena polymorpha, on Community Nitrogen Dynamics in Saginaw Bay, Lake Huron, NOAA Great Lakes Environmental Research Laboratory, University of Michigan, Kent State University, Texas A&M University

Reprinted from Journal of Great Lakes Research 21(4):529-544, International Association of Great Lakes Research, 1995.

Effects of the Zebra Mussel, Dreissena polymorpha, on Community Nitrogen Dynamics in Saginaw Bay, Lake Huron

Abstract
The effects of the zebra mussel, Dreissena polymorpha, on chlorophyll and nutrient con centration changes and community ammonium uptake and regeneration rates were determined in bottle experiments on waters collected from a eutrophic site and an oligotrophic site in Saginaw Buy. Lake Huron in 1992. Our objectives were to estimate nitrogen cycling rates and to determine the direct (excre tion) and indirect (foodweb) effects of the zebra mussel on these rates. Isotope labeling experiments with added ¹⁵ NH ₄ ⁺ were conducted on waters collected on five sampling dates between April and October. Direct effects of zebra mussels on ammonium regeneration and potential uptake were examined by com paring results from bottles incubated with (1.5 individuals in 4 L lake water) and without added zebra mussels. Indirect foodweb effects were examined by measuring regeneration and potential uptake rates in subsamples of water that had previously been incubated in the presence or absence of zebra mussels.

Zebra mussels removed a large fraction of chlorophyll from the oligotrophic site on all sampling dates and from the eutrophic site in October, but had a negligible effect on chlorophyll levels in waters from the eutrophic site in June, July, August, and September when cyanophytes were abundant. Community ammo nium regeneration rates and uptake rates both followed seasonal patterns resembling those for chloro phyll concentrations in control treatments at the eutrophic site. Rates for water from the oligotrophic site were low (usually not significantly different from zero) and are not reported here. Community ammonium regeneration rates were consistently enhanced in the presence of zebra mussels, indicating that zebra mussel excretion could have a dominant effect on nitrogen regeneration in regions where it is abundant. Zebra mussels appeared to decrease community uptake rates of ammonium in August and September but did not predictably affect nitrogen remineralization rates by other lower foodweb organisms (e.g. bacteria, protozoans, zooplankton).

Entire Paper
Contact: W.S Gardner, NOAA Great Lakes Environmental Research Laboratory, 2205 Commonwealth Blvd., Ann Arbor, Michigan 48105
Keywords: Zebra_mussel, Ecological_interactions, Environmental_impacts
Product Type: Research, Basic_biology, Impact
User Type: General