luation of Fish Communities and Habitat in a Drought Year
Angie M. Spence, Melissa L. Smith and Robert W. Nairn
School of Civil Engineering and Environmental Science, 202 West Boyd Street Room 334,The University of Oklahoma, Norman, OK 73019
Assessment of stream ecological health by monitoring chemical water quality alone fails to include important physical habitat
and biological integrity parameters that may be critical to a valid assessment of human impact. As part of a larger monitoring
effort, we performed rapid ecological assessments, including both habitat and biological community evaluations, for 10
streams in three central Oklahoma counties during the summer of 1998. Habitat assessments and fish collections were
conducted on predetermined 400-m stream reaches. The fish community index of biotic integrity (IBI) and a standard habitat
scoring procedure were used to estimate overall ecological health of study streams by comparison to reference streams.
Habitat scores ranged from 44 to 89 (possible maximum = 180). During the summer 1998 drought, flow-dependent habitat
parameters (e.g., pool variability, presence of rocky runs and riffles) significantly affected habitat quality. For individual
streams, the total number of fish species and individuals ranged from 1 to 14 and 1 to 292, respectively. The most common
species collected was Lepomis cyanellus, which was collected in all streams. Fish IBI scores ranged from 10 to 28 for the study
streams and integrity classes ranged from very poor to fair, with positive reference streams rated excellent. A comparison of
IBI and habitat scores for each stream provided insight into possible water quality concerns. Discrepancies between the actual
and expected scores, based on reference streams, are indicative of either habitat degradation or water pollution problems. A
combination of habitat and biological community assessment provided a quick and inexpensive tool for evaluating stream
ecosystem health. ©1999 Oklahoma Academy of Science