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Coulas, R.A., H.J. MacIsaac, and W. Dunlop, 1998. Selective Predation on an
Introduced Zooplankter (Bythotrephes cederstroemi) by Lake Herring (Coregonus
artedii) in Harp Lake, Ontario. University of Windsor
Reprinted with permission from Freshwater
Biology (1998) 40: 343-355
Selective Predation on an Introduced Zooplankter
(Bythotrephes cederstroemi) by Lake Herring (Coregonus artedii) in Harp
Lake, Ontario
SUMMARY
- Bythotrephes cederstroemi (Crustacea: Onychopoda:
Cercopagidae) invaded Harp Lake, Ontario in 1993, since when the zooplankton community has
shifted from dominance of small-bodied to large-bodied species. During 1995 diets of adult
lake herring (Coregonus artedii), Harp Lake's primary planktivorous fish, were
examined to determine the extent to which this conspicuous zooplankter has become
integrated into the lake's foodweb and whether fish condition has been affected in
consequence.
- Bythotrephes and Daphnia galeata mendotae were
strongly preferred prey, whilst Holopedium gibberum and calanoid and cyclopoid
copepods were negatively selected by lake herring. Predation on Bythotrephes and Holopedium
was not size-selective, although D. galeata mendotae and calanoid copepods (Leptodiaptomus
minutus and L. sicilis) consumed by herring were significantly larger than
co-occurring conspecifics in the lake.
- Caudal spines of Bythotrephes may form boluses in lake
herring stomachs. However, the number of caudal spines in fish digestive tracts did not
differ significantly from the number of Bythotrephes' mandible pairs, indicating
that the former were not differentially retained.
- Lake herring weight-at-length relationships in lakes in Muskoka,
Ontario, invaded by Bythotrephes did not differ from those in adjacent non-invaded
lakes, indicating that Bythotrephes invasion of lakes apparently has not affected
condition of lake herring.
Entire Paper
Contact: Hugh J. MacIsaac, Great Lakes Institute for Environmental Research,
University of Windsor, Windsor, ON N9B 3P4
www.blackwell-science.com/
Keywords: Bythotrephes, Ecological_interactions, Environmental_impacts
Product Type: Research,
Impact
User Type: Resource_management
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