T-Feeding ecology of 3 omnivorous fishes in a large southern United States reservoir
was investigated to develop hypotheses on the potential functional roles of these species in this
ecosystem. I examined distribution, abundance, and diet of smallmouth buffalo (Ictiobus bubalus),
river carpsucker (Carpiodes carpio), and gizzard shad (Dorosoma cepedianum) relative to the availability
of potential resources during summer 1997 and 1998. In July and August, abundance of
smallmouth buffalo was significantly greater at stations with depths of 10 m than at 1 m or 3 m
stations. There was no significant difference in abundance of gizzard shad or river carpsucker by
depth or month. Relative proportions of detritus and zooplankton in the diet varied among species.
Smallmouth buffalo primarily ate copepods, whereas gizzard shad primarily ate detritus. The
diet of river carpsucker was intermediate in relative proportions of zooplankton and detritus to
that of smallmouth buffalo and gizzard shad. Of the 3 species examined, only gizzard shad showed
a significant decline in dietary crude protein, phosphorus, and organic content over the summer.
This corresponded to a decline in condition of gizzard shad. Overall, benthic invertebrates had a
heterogeneous distribution within the reservoir, and organic content of sediments was not different
across sample stations. Relative importance to ecosystem functioning of these species, all of
which are highly abundant in southern reservoirs, likely depends on species-specific feeding ecology
and environmental conditions.