Analysis of six foraging behaviors as toxicity indicators, using juvenile smallmouth bass exposed to low environmental pH.

Six foraging behaviors were evaluated for use in toxicity bioassays with fishes. Response time and strike frequency were used to measure fish activity, average and longest fixation distance, to measure visual acuity, while prey capture frequency and strike success were used to measure fish coordination and agility. In this study, the feeding behaviors were used to evaluate the effects of chronic exposure to acidic water on juvenile smallmouth bass (Micropterus dolomieui). Feeding responses to two types of live prey, tubificids and Daphnia magna, were recorded for bass exposed to pH 4.7 and 4.2. Fish held at the lower pH level had significantly lower fixation distances, prey capture success and capture frequencies with both prey types, indicating that high levels of acidity may impair visual acuity, coordination, and agility. The foraging behaviors evaluated herein appear to be useful in toxicity testing because they are easily quantified and indicate changes that may affect growth and survival in long-term exposures.