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Berkman, P.A., D.W. Garton, and S.J. Van Bloem, 1994. Zebra Mussel Habitat Expansion by Soft Substrate Modification, Ohio State University, Ohio Sea Grant, Columbus and Indiana University Reprinted from American Zoologist 34(5): 60A Zebra Mussel Habitat Expansion by Soft Substrate ModificationPopulations of the zebra mussel (Dreissena polymorpha) were studied in western Lake Erie with sidescan sonar and remotely operated vehicles along with in situ collections to assess their expansion into soft substrate habitats. Because Dreissena has byssal threads for attaching to hard substrates, soft substrates have not been considered to be suitable habitats. However, this study clearly demonstrates that dense Dreissena populations exist in an extensive mosaic on sand and silt substrates. Microscopic examination of Dreissena assemblages on these soft substrates revealed that recently metamorphosed mussels can propagate their byssal threads over individual grains smaller than 1.0 mm. These byssal threads then proliferate, creating a conglomerate of sand grains for subsequent mussel colonization. This zebra mussel recruitment mechanism in soft substrate areas reflects their adaptive capacity to spread into novel habitats. Consequently, models which forecast the ecological impacts of this species must include their population dynamics in both hard and soft substrates. Contact: P.A. Berkman, Ohio State University, Ohio Sea Grant |