The effects of four pesticides on respiration, coughing, and heart rates of rainbow trout, Salmo gairdneri Richardson

The effects of short-term exposure to the organophosphate, azinphos methyl, the carbamate, carbaryl and the organochlorines, HEOD and DDT on the respiration, coughing and heart rates of juvenile rainbow trout (Salmo gairdneri Richardson) were studied. No significant changes in the investigated parameters were observed in control fish exposed to uncontaminated acetone in water. Breathing and heart rates were depressed in fish exposed to azinphos methyl (possibly due to AChE inhibition), and heart rates were depressed in fish exposed to carbaryl. Coughing rates increased initially in the latter group, indicating a peripheral effect on the gills, but declined to normal levels rapidly. Respiration and heart rates were depressed, and coughing rates increased initially in fish exposed to HEOD. Observed responses to DDT exposure (increased respiration and decreased heart rates) indicated impairment of oxygen uptake, perhaps caused by the large increase in coughing rates. Physiological responses were related to pesticide concentration in all experiments. Results must be viewed with regard to possible physiological acclimation to the pesticide concentration, and absorption of the pesticide from the water by the fish. A sublethal water quality index based on the physiological parameters studied, seemed practical only for detection of DDT.