The effects of predation by threadfin shad, dorosoma petenense, and competition on body length of diaptomus in Piedmont North Carolina lakes

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Ronald Darwin Walker (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Robert Stavn

Abstract: The species diversity of diaptomid copepods in piedmont North Carolina lakes has increased since these lakes were surveyed by McKee and Coker in 1940. This has been due, in large part, to the introduction of the vertebrate predator threadfin shad (Dorosoma petenense) and its effect on the only two diaptomid copepods present at that time, Diaptomus birgei and Diaptomus reighardi. These two copepods were never found together at the time of McKee and Coker’s survey, one or the other occupying the entire "Diaptomus niche" in any given lake. Ecological maturation of these lakes coupled with predation by Dorosoma petenense has enabled ether diaptomid copepods such as D. pallidus and D). mississippiensis to enter these lakes and also has allowed the coexistence of D. birgei and D. reighardi. Study of seasonal fluctuations in copepod population densities has shown that in shad-inhabited lakes the larger species tend to be dominant during times of low shad predation and the smaller species become dominant when shad activity is high (Beavers and Stavn 1975) . To test the degree of size selectivity of prey by shad, measurements were made of a single species (D. reighardi) over a one-year period in two lakes, one lake with and the other lake without shad. Seasonal variation in mean length was found to be similar in the two lakes during winter and early spring; however, from late spring through fall mean length of D. reighardi dropped below the yearly average to a greater degree in the shad-inhabited lake. This latter time period corresponded to the time of the year when shad were active in the shad-inhabited lake.

Additional Information

Language: English
Date: 1978
Lake ecology $z North Carolina $z Jeanette, Lake
Shad $x Habitat
Jeanette, Lake (N.C.)

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