Ecological Assessment of Several Central Oklahoma Streams Through Evaluation of Fish Communities and Habitat in a Drought Year

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