Sierszen, M.E., J.R. Keough, and C.A. Hagley, 1996. Trophic Analysis of Ruffe (Gymnocephalus cernuus) and White Perch (Morone americana) in a Lake Superior Coastal Food Web, Using Stable Isotope Techniques, US EPA.

Reprinted with Permission from Journal of Great Lakes Research (1996) 22(2): 436-443

Trophic Analysis of Ruffe (Gymnocephalus cernuus) and White Perch (Morone americana) in a Lake Superior Coastal Food Web, Using Stable Isotope Techniques

Abstract
We examined the trophic roles of two nonindigenous species, ruffe (Gymnocephalus cernuus) and white perch (Morone americana), in the food web of a western Lake Superior coastal wetland, using stable isotope techniques. The §¹⁵N signature of ruffe was similar to published values for YOY yellow perch (Perca flavescens), and intermediate to those of white sucker (Catostomus commersoni), a benthivore, and alewife (Alosa pseudoharengus), a planktivore. Ruffe of all sizes sampled had an approximately 45 enrichment in ¹⁵N over published values for benthos, and a 3%¹⁵N enrichment over values for plankton. A 3-4% difference is consistent with commonly reported shifts in §¹⁵N signature between food and prey. These results suggest that ruffe in this food web feed on both benthos and plankton. White perch undergo ontogenetic shifts in nitrogen isotope signatures similar to those reported earlier for yellow perch, and appear to become piscivorous by the time they are 25 cm long. Our data suggest that interactions between ruffe and yellow perch could represent a competitive bottleneck. If yellow perch are able to grow large enough to become piscivorous, they should be able to escape competition with ruffe. In contrast, white perch appear to have the potential to compete with yellow perch throughout their lives.

Entire Paper
Contact: Michael Sierszen, US EPA, Mid-Continent Ecology Division, 6201 Congdon Blvd., Duluth, MN 55804
Key Words: Ruffe, White_perch, Population_dynamics, Environmental_impacts
Product Type: Research, Impact
User Type: General