Abstract |
A 96-hour toxicity test with fish ventilation frequency as the response variable was developed to estimate safe zinc concentrations for steelhead Salmo gairdneri. Two Oregon steelhead strains were exposed to zinc at different water temperatures and total hardnesses (7, 12, and 17C; 25 and 125 mg/liter as CaCO3). Ventilation frequencies enumerated from bioelectric potential generated by buccal and opercular openings and closings showed significant increases at the highest test concentration in five of 10 tests. This indicates that ventilation-frequency tests are at least as sensitive as long-term toxicity tests and may be used to screen chemicals for potential harmful effects on fish. |