BEHAVIOR MODIFICATION IN BONYTAIL CHUB (Gila elegans) EXPOSED TO TREATED MUNICIPAL EFFLUENT; COVER-SEEKING, SPACING AND ACTIVITY LEVEL

Abstract

We exposed endangered bonytail chub (Gila elegans) to secondarily-treated municipal wastewater previously shown to containing low-levels of known endocrine disrupting compounds for 2.5 years. We examined; growth, cover-seeking, behavioral reaction to disturbance, spacing, activity level and chasing/paired swimming event. Fish in raceways containing municipal effluent grew larger than fish in control raceways by the end of the experiment. Bonytail chub in treatment raceways were out of cover more often when disturbed, less clumped outside of cover, and more active than fish in control raceways. There was no difference in the number of chasing/paired swimming events between fish in treatment and control raceways. Behavioral differences in fish exposed to municipal effluent may adversely affect wild bonytail chub, especially if they have to combat a variety of environmental stressors and disturbances.