Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Biology

Supervisor

Dr. Scott Petrie

Abstract

Invasion by mussels can cause rapid increases in the abundance of submerged aquatic vegetation (SAV) by increasing water clarity and altering nutrient cycling, but rapid expansion of the mussel population is often followed by a decline until a new regional carrying capacity is reached. I sampled Long Point Bay (LPB), Lake Erie, in 2009 to quantify changes in SAV communities and densities of zebra mussels (Dreissena polymorpha) since the peak of the latter in the early 1990s, and modeled influences of year, water depth, and substrate type on the probability of SAV detection. I detected a 96% decrease in mussel abundance/m2 (±SE) between 1992 ( = 457 ± 86) and 2009 ( = 19 ± 2). The five most abundant SAV species in 1992 had decreased by 2009. Water depth and substrate type influenced probability of detection of SAV species, suggesting that changes in Lake Erie water levels and sediment loading influence SAV communities. Carrying capacity of LPB for waterfowl and other fish and wildlife that use and eat SAV and mussels increased during the mid-1990s, but has since decreased.

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