Publication Date


Document Type


First Advisor

Ende, Carl von

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Cladocera--Michigan--Upper Peninsula; Fresh-water zooplankton--Michigan--Upper Peninsula; Holopedium gibberum; Bog ecology--Michigan--Upper Peninsula


Pour small, fishless acid bog-lakes located in the Upper Peninsula of Michigan exhibit an interesting pattern of zooplankton community structure with respect to the cladoceran Holopedium gibberum. Holopedium is found in only two of the four lakes. The lakes with Holopedium possess relatively complex zooplankton communities, whereas the lakes without Holopedium have simple communities, dominated by the cladoceran Daphnia pulex. Daphnia is also present in the lakes with Holopedium, but only' in low abundance. It was hypothesized that Holopedium was absent from the two lakes as the result of competitive exclusion by Daphnia. The ability of Holopedium to survive in a Holopedium-free lake with and without Daphnia was tested in container and large enclosure experiments performed in Tender Bog in the summers of 1982 and 1983. Holopedium survived readily when raised alone, but did poorly in most replicates when raised with Daphnia. When raised with Daphnia and the predaceous phantom midge larva (Chaoborus americanus), Holopedium was able to attain moderate densities before failing. Daphnia was exterpated in this condition. The Forest Service Bog Holopedium population was monitored with respect to density and swarming behavior during the course of this investigation. Holopedium was found to form small, dense swarms near the edges of Forest Service Bog. No such swarming behavior was observed in the Holopedium populations found in two neighboring lakes in which fish are present. It is suggested that the swarming behavior observed in the Forest Service Bog Holopedium population may be unique to this species in clear, fishless bog-lakes, and that it may be a mechanism for avoiding competition with other zooplankton species. It was concluded that Holopedium is absent from Tender Bog due in part to out-competition by Daphnia, though the mechanism of this competition remains to be determined. An alternative hypothesis and possible mechanism explaining the absence of Holopedium from Tender Bog is proposed based upon the unique swarming behavior observed in the Forest Service Bog Holopedium population.


Bibliography : pages 186-195.


x, 197 pages




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