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|Title:||The Importance of Cover and Other Habitat Features to The Distribution and Abundance of Illinois Stream Fishes (Sunfish, Cyprinids)|
|Author(s):||Angermeier, Paul Leo|
|Department / Program:||Biology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
Agriculture, Fisheries and Aquaculture
|Abstract:||Effects of spatio-temporal changes in habitat structure on the distribution and abundance of stream fishes were assessed using field and laboratory results. Fish distributions in several small Illinois streams were related to the availability of depth and cover features using survey data and cover manipulations. Large fish were more often associated with deep areas and cover than small fish; centrarchids were more often associated with these features than cyprinids. Depth was a better predictor of fish distribution than cover, but correlations between fish abundances and habitat features varied among streams and years. In general, fish were more strongly associated with habitat features in homogeneous streams than in structurally complex ones.
Removal of woody debris affected channel morphology, organic litter and fish abundances in upstream areas. Compared with unaltered sites, altered sites suffered accentuated losses of deep habitats during low-flow periods due to filling by fine, shifting substrates. In addition, the abundance of organic litter covering the stream bottom was reduced in altered sites. Effects were less pronounced the following year, when exceptionally high precipitation maintained stable stream discharge throughout the year. Fish abundance and community structure exhibited increased temporal instability in altered sites relative to unaltered sites. Effects of debris removal were minimal in a downstream area where coarse, stable substrates predominated.
Effects of current and predator presence on cover use by small fish were examined in a laboratory stream. Small sunfish were more attracted to cover than small cyprinids. Small fish increased their use of cover in the absence of current and were less active when predators were present. Sunfish avoided predators better in the presence of current, but cyprinids did not.
Effects of fish consumption on the abundance of benthic invertebrates were evaluated using paired screen exclosure. One exclosure of each pair allowed access to fish (open exclosure), while the other did not (closed exclosure). Upstream densities of the most abundant invertebrate taxa and the largest individuals were greater in closed than in open exclosures, but downstream densities did not follow these patterns.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
|Date Available in IDEALS:||2015-05-14|