Can Filter Feeding by Dreissenid Mussels Account for the Diatom Decline in Lake Michigan?

Session: Poster session

Hunter Carrick, Central Michigan University, [email protected]
Christopher VanCuren, Department of Biology, Central Michigan University, [email protected]
Henry Vanderploeg, NOAA GLERL, [email protected]

Abstract

Over the past 100 years, the Great Lakes ecosystem has been repeatedly colonized by a variety of non-native species; however, the introduction of dreissenid mussels has been associated with some of the most significant changes observed throughout the ecosystem.  That said, few experiments have been performed to evaluate the potential effect the presence of invasive mussels have had on the native plankton food web.  We performed three experiments (May, August, December 2013/14) using a series of large enclosures that housed a native, offshore plankton assemblages exposed to the presence or absence of dreissenid mussels.  In terms of results, total density of plankton cells was not difference between mussel treatments (absence versus presence).  That said, the presence of mussels appears to contribute to greater uncertain in the assemblage of plankton (and perhaps greater instability). In the summer, we observed the largest decline in phototrophic nanoplankton abundance (mainly cryptomonads, 50%), while the largest decline in phototrophic microplankton (mainly diatoms) was measured in the winter  and spring experiments.  Our results suggest that the mussels selectively fed on diatoms during the water colder periods, could account for the decreased abundance of spring diatoms observed in Lake Michigan (50% reduction).

1. Keyword
Dreissena

2. Keyword
diatoms

3. Keyword
plankton