Changes in the benthic algal community and nutrient limitation in Saginaw Bay, Lake Huron, during the invasion of the zebra mussel (Dreissena polymorpha)

Abstract

AbstractWe conducted a series of nutrient manipulation experiments over the first 5 y of Dreissena colonization in Saginaw Bay, Lake Huron, to evaluate benthic algal nutrient limitation and community composition. We placed nutrient-diffusing substrata in the littoral zone of the Bay during 1991 (early Dreissena colonization) and from 1992 to 1995 (post-Dreissena colonization). The treatments consisted of P, N, and P+N additions, and a control. Chlorophyll a decreased through time from 1992 to 1995. Phosphorus limited biovolume only in 1994. Treatments with P additions had significantly more chlorophyll a than the controls each year after 1992. This result was consistent with an observed decrease in dissolved P throughout the study. Nitrogen additions had no significant effect throughout the 5-y period. Major shifts in species composition did not result from nutrient additions but rather seemed to be consistent with changes in light penetration and Dreissena herbivory. Our data demonstrated that the pre-Dr...