EFFECTS OF HIGH LEVELS OF INORGANIC PHOSPHATE ON AQUATIC ORGANISMS IN PHOSPHATE-RICH ENVIRONMENTS.

A process for monitoring cardiac and opercular rates in the channel catfish was developed utilizing unimplanted electrodes. Cardiac rates increased with increasing phosphate levels up to 15-20 mg/l. No further increases were observed at levels up to 160 mg/l. Chronic exposure at 20 mg/l phosphate revealed no accommodation to the phosphate-induced cardiac rate elevation. A technique developed for monitoring basal metabolic function demonstrated increased metabolic rates in the channel catfish with increasing phosphate levels up to concentrations of 10 to 15 mg/l. Biochemical studies in which the activities of the enzymes lactate dehydrogenase, pyruvate kinase, and hexokinase were monitored after exposure to phosphate and sulfate gave varied results.