Selective impact of filter-feeding gizzard shad on zooplankton community structure

Comparison of ponds containing gizzard shad with control ponds without fish showed that gizzard shad predation suppressed populations of Keratella sp., Diaphanosoma brachyurum, copepod nauplii, Chaoborus sp., and cyclopoid copepodids and adults, but enhanced populations of Diaptomus pallidus copepodids and adults. These results confirm previous laboratory studies which showed that filter-feeding gizzard shad are not size-selective predators, as is typically assumed of planktivorous fish, but instead feed on those animals which have little ability to escape, so that their predation results in a community shift toward the more evasive prey.