Responses of Fish and Macroinvertebrate communities to Variations in Habitat and Water Quality in Streams of the San Joaquin Valley, California

Larry R. Brown

In:
Sorenson, S.K., ed., Proceedings abstracts of the American Water Resources Association's symposium on the National Water-Quality Assessment (NAWQA) Program -- November 7-9, 1994, Chicago, Illinois: U.S. Geological Survey Open-File Report 94-397, p. 20.

Abstract:
The San Joaquin-Tulare Basins study unit of the U.S. Geological Survey's National Water Quality Assessment Program includes 28,500 square miles in central California. In 1993, 13 stations were sampled ranging from relatively pristine sites in the Sierra Nevada to a small creek used as an agricultural drain. A total of 31 species of fish were captured; ten were native to California and 21 were introduced. Multivariate analyses identified three major groups of co-occurring species, one composed of native fishes and the other two of introduced fishes. The abundance of one introduced species group, characterized by minnows, was positively associated with increased specific conductance, hardness, pH, and nutrients. This group also was positively associated with streams of fine substrate and little instream cover. The native species group was negatively associated with both sets of variables. The other group of introduced species, characterized by bass and sunfish, was positively associated with stream discharge, depth, and width but was not related to water quality. Macroinvertebrates, especially insects, were most diverse at the Sierra Nevada sites. The diversity of mayflies, caddisflies, and stoneflies was especially low on the valley floor. Both fishes and macroinvertebrates were useful indicators of water quality and habitat conditions.