Upper Midwest Environmental Sciences Center
Population dynamics of zebra mussels Dreissena polymorpha (Pallas, 1771) during the initial invasion of the Upper Mississippi River
Cope, W. G., M. R. Bartsch, and J. E. Hightower, 2006, Population dynamics of zebra mussels Dreissena polymorpha (Pallas, 1771) during the initial invasion of the Upper Mississippi River: Journal of Molluscan Studies Supplement, v. 72, p. 179-188.
The aim of this study was to document and model
the population dynamics of zebra mussels Dreissena polymorpha (Pallas,
1771) in Pool 8 of the Upper Mississippi River (UMR), USA, for five consecutive
years (1992-1996) following their initial discovery in September 1991. Artificial
substrates (concrete blocks, 0.49 m2 surface area) were deployed on
or around the first of May at two sites within each of two habitat types (main
channel border and contiguous backwater). Blocks were removed monthly (30 +/-
10 d) from the end of May to the end of October to obtain density and growth information.
Some blocks deployed in May 1995 were retrieved in April 1996 to obtain information
about over-winter growth and survival. The annual density of zebra mussels in
Pool 8 of the UMR increased from 3.5/m2 in 1992 to 14,956/m2
in 1996. The average May-October growth rate of newly recruited individuals, based
on a von Bertalanffy growth model fitted to monthly shell-length composition data,
was 0.11 mm/d. Model estimates of the average survival rate varied from 21 to
100% per month. Estimated recruitment varied substantially among months, with
highest levels occurring in September-October of 1994 and 1996, and in July of
1995. Recruitment and density in both habitat types increased by two orders of
magnitude in 1996. Follow-up studies will be necessary to assess the long-term
stability of zebra mussel populations in the UMR; this study provides the critical
baseline information needed for those future comparisons.
Lake St-Clair, Great lakes, North America, Shell growth, Predation, Fishes, Erie, Frequency, Ecology, Impact