Predation on the exotic spiny water flea Bythotrephes cederstroemi by lake herring Coregonus artedi in Harp Lake, Ontario.

The predaceous, spiny water flea Bythotrephes cederstroemi invaded the Great Lakes in the early 1980\u27s, and Harp Lake in 1993. Harp Lake, a small inland waterbody in central Ontario, provides an excellent opportunity with which to assess ecological perturbations involving this exotic species at a tractable spatial scale. Lake herring (Coregonus artedi) and zooplankton were sampled during summer and autumn 1995. Diets of lake herring were examined and compared with zooplankton taxa in the plankton. Fish demonstrated strong positive selection for Bythotrephes and Daphnia spp., and negative selection for Holopedium gibberum and calanoid and cyclopoid copepods. An examination of the occurrence of Bythotrephes tailspines and mandibles in fish digestive tracts revealed that tailspines were not differentially retained, and that the formation of dense tailspines boluses appears to have no effect on their retention in the digestive tract. An assessment of lake herring weight at length relationships in invaded and noninvaded lakes in central Ontario revealed no significant differences in fish growth rates attributable to invasion by Bythotrephes. Results from this study indicate that adult lake herring readily incorporate Bythotrephes into their diet in invaded lakes. However, it is not evident whether lake herring are beneficially or adversely affected by lake invasion of, and predation on, Bythotrephes.Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1996 .C68. Source: Masters Abstracts International, Volume: 37-01, page: 0178. Adviser: Hugh J. MacIsaac. Thesis (M.Sc.)--University of Windsor (Canada), 1996