Responses of Ohio River and Lake Erie dreissenid molluscs to changes in temperature and turbidity

Abstract

To predict possible effects of global climatic change (via changes in ambient water temperatures and suspended sediments) on two exotic bivalves (zebra mussel, Dreissena polymorpha, and quagga mussel, Dreissena bugensis), we evaluated survival and growth at three temperatures (ambient, ambient + 2°C, and ambient + 4°C) and two turbidities (ambient and twice ambient) in outdoor tanks for approximately 3 months during both warm and cool seasons. We compared responses of zebra and quagga mussels from southwestern Lake Erie and zebra mussel from the Ohio River at Louisville, Kentucky. Experimental increases in temperature significantly enhanced growth rates in fall - early winter but not during summer - early fall. Elevated temperatures increased mortality in the warm season but not in the cool season. Zebra mussel survived better (especially the Ohio River population) than did quagga mussel at high temperatures. Inorganic turbidity had few detectable effects; relationships, where significant, varied with temperature and species. Based on these experiments and related laboratory studies, we predict that populations of Dreissena in the Ohio River and farther south will suffer overall if water temperatures increase. In contrast, more northern populations of Dreissena will probably benefit from predicted climatic change and may extend their range to higher latitudes and altitudes.