ABSTRACT
We quantify temporal and spatial trends in densities of main taxonomic groups of phytoplankton, zooplankton, and benthic macroinvertebrates relative to the colonization of Saginaw Bay, Lake Huron, by zebra mussels (Dreissena polymorpha) in 1990-1996. We used data from bay-wide surveys and generalized linear models (GLMs). Mussels were rst found in 1991, peaked in 1992, and declined to stable levels in 1993 at stations with hard substrates where they were most abundant. Annual trends in phytoplankton and zooplankton were negatively correlated with zebra mussel trends at different time lags. Most phytoplankton taxa declined within three years of mussel colonization, with disappearance of photosensitive cyanophytes in the rst year of colonization. All phytoplankton taxa tended to recover within 5 years except for cyanophytes and chlorophytes.
