PARENT SESSION
Contributed Oral Session 35: Invasive Species: Great Lakes Area
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 524 B, Level 5, Palais des congrès de Montréal

A meta-analysis of the effects of invasive mussels on freshwater benthic communities.

Ward, Jessica^*,1, Ricciardi, Anthony¹, ¹ McGill University, Montreal, Quebec, Canada

ABSTRACT- Invasive dreissenid mussels (the zebra mussel Dreissena polymorpha and the quagga mussel Dreissena bugensis) dominate many freshwater benthic communities in Europe and North America. Numerous experimental studies and field surveys suggest that dreissenid invasions alter macroinvertebrate diversity and abundance; however, the observed effects vary in magnitude and direction across studies. To explain this variation, we conducted a meta-analysis of 25 independent studies to test the influence of extrinsic variables including habitat type, time since invasion, and trophic status of individual taxa. The effect of mussels on total macroinvertebrate density (excluding Dreissena) was positive in littoral habitats, but its magnitude varied with time since invasion. The magnitude of this effect did not differ between habitats dominated by soft sediments versus habitats dominated by rocky substrates. Furthermore, an analysis of experimental studies found no difference in the effect on macroinvertebrate density associated with empty-shell treatments versus living mussel treatments, suggesting that total density is influenced more by shell-generated habitat than by biodeposition. Effects varied among taxa, but in many cases were consistent across studies, suggesting predictable patterns in response to Dreissena invasion.

Key words: invasive species, nonindigenous, bioengineer, community ecology