8133

• UCREFRP Catalog Number: 8133
• Author: Collins, K. and D. K. Shiozawa.
• Title: The Effects of Fish Predation on Backwater Invertebrate Communities of the Green River, Utah\
• USFW Year: 1996.
• Copyright Material: NO

EXECUTIVE SUMMARY
The potential role of fish predation on the structure of invertebrate communities in
backwater habitats of the Green River, a large river in eastern Utah, was examined by placing
a series of complete, partial, and no fish exclosures in backwater habitats and sampling benthic
and planktonic communities periodically through the summer. The taxa showing the greatest
direct treatment effects were the chironomid genus Tan us, the corixidae, and the planktonic
adult copepoda. The benthic densities of the naupliar and copepodite stages of copepods
showed a negative response to fish exclusion, probably the result of increased levels of
corixidae and Taus, which are known to prey on benthic organisms. This study indicates
that backwater fishes may impact food resources, although invertebrate predation may act in a
compensatory manner on certain invertebrate species. This suggests that Colorado squawfish
!Uchocheilus lucius may undergo resource competition during their post-larval stage. More
research is necessary to determine if this is the case.
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