Lamberti, G.A., A.H. Fullerton, D.M. Lodge, and M.B. Berg, 1997.  Exploitation of Benthic Invertebrates by Ruffe: Laboratory Experiments, Field Surveys, and Predictions for the Great Lakes, University of Notre Dame, Loyola University of Chicago

ABSTRACT
We investigated the potential impacts of ruffe (Gymnocephalus cernuus) on the benthic macroinvertebrates of the Great Lakes by (1) conducting laboratory feeding preference studies with a wide variety of benthic invertebrates, (2) sampling benthic invertebrates from areas of Lake Michigan suspected to be susceptible to ruffe invasion, and (3) compiling existing data on invertebrate community structure from all of the Great Lakes. In laboratory assays, ruffe preferred soft-bodied invertebrates over those protected by shells or cases. Ivlev's electivity index revealed similar preference for chironomid midges, mayflies (Ephemeroptera), caseless caddisflies (Trichoptera), and amphipods and complete avoidance of snails, bivalves, cased caddisflies, and beetles (Coleoptera). The preferred taxa were consistent with analyses of ruffe gut contents conducted by Ogle (1992) in Duluth Harbor of Lake Superior. Our 1996 field survey of nearshore areas and embayments of non-invaded Lake Michigan showed that 95% of the soft-sediment macrobenthic fauna by numbers consisted of chironomids and amphipods, suggesting that preferred food for ruffe is plentiful and that ruffe may have significant effects on benthic community structure in that lake. We compiled macroinvertebrate data from published studies of the other Great Lakes to predict the potential impacts of a ruffe invasion. All lakes had preferred food taxa for ruffe that ranked among the top-5 most numerous taxa. In non-invaded areas of Lake Superior, amphipods and oligochaetes are co-dominant while chironomids and oligochaetes are most abundant in Lake Huron. Lake Erie contains high densities of invulnerable bivalves (exotic zebra mussels and sphaeriid clams), but other invertebrates may show further reductions in relative abundance if ruffe invade. Nearshore areas of Lake Ontario have abundant zebra mussels and snails, which are unlikely to respond directly to ruffe, but numerous amphipods and isopods that may decline in the lake. All of the Great Lakes contain prey suitable for ruffe, but the presence of zebra mussels may mediate the impacts of ruffe on the benthic macroinvertebrate fauna.

Contact: Gary A. Lamberti, Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556 or Gary.A.Lamberti@nd.edu
Keywords: Ruffe, Ecological_interactions, Zebra_mussel
Product Type: Publications, Conference_proceedings
User Type: General