http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Effects of an introduced predator on the native fish assemblage in the Devils River, Texas
xiii, 95 leaves : illustrations ; 28 cm.
The Devils River is regarded as a pristine aquatic system in the semi-arid southwest, but in recent years, there have been declines in certain fish species' abundances, and four fishes in the area are currently listed as threatened by the state. Micropterus dolomite (smallmouth bass) is an introduced predator in this system that may have contributed to the decline of these fishes. The objective of this study was to test the impact of this exotic on the native fish assemblage with a predator removal experiment. Sampling was performed in runs, riffles, and channel margins to evaluate potential changes in abundance, length distribution, or habitat use that may have occurred among native species following the introduction of the smallmouth bass. Diversity (H') was found to be slightly higher over the course of the 14 month experiment in the "bass removed'' reach. A principal components analysis (PCA) formed on species abundance data revealed some divergence of species distributions occurring between reaches. Canonical correlation analysis (CANCOR) showed that more species used the run habitats across a broader temporal scale in the experimental reach, suggesting smallmouth bass predation may be greater in this habitat type. A repeated measures analysis of variance (ANOVA) showed a significant effect of the experimental removal of smallmouth bass on the abundance of Etheostoma grahami. Although the ANOVA did not show a significant difference in the abundance of any other species, Cyprinella proserpina and Notropis amabilis had trends that suggested an effect, particularly during the summer. Cyprinella proserpina and Notropis amabilis also both appeared to be more susceptible to smallmouth bass predation in larger size classes. Finally, Cyprinella proserpina was the only species to show a difference in habitat use patterns. This species used the riffle habitats most frequently when the smallmouth bass were present. As a non-native piscivore in this system, the smallmouth bass appear to be influencing assemblage-level interactions to the detriment of several native species in the Devils River.
"Major subject: Wildlife and Fisheries Sciences".
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references (leaves 73-77).