ISSN:
1365-2427
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
1. Following the 1993 invasion of Harp Lake by Bythotrephes longimanus a number of small-bodied zooplankton declined dramatically compared to pre-invasion densities, and some larger species increased.
2. To test whether these changes were caused by Bythotrephes, we measured its consumption of zooplankton in 1995 and compared this to production by the prey species with which it overlapped spatially and temporally.
3. On a seasonal basis Bythotrephes consumption was 199 mg dry mass (DM) m−2, or 25% of zooplankton production which was 783 mg DW m−2. However, for some species, such as the small copepod Tropocyclops extensus, consumption greatly exceeded production—this was one of the species noted to decline in Harp Lake following the appearance of Bythotrephes. By contrast, for the larger cladocerans Daphnia galeata mendotae and Holopedium gibberum, consumption was much less than production—these species were observed to increase following the invasion.
4. Our results thus support the hypothesis that zooplankton changes in Harp Lake were caused by Bythotrephes. We speculate that lower quality prey remaining in Harp Lake may lead to reduced densities of Bythotrephes, or impose strong selective forces that lead to new adaptations by this predator.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2427.2001.00649.x
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