Sublethal responses to pesticides of several species of australian freshwater fish and crustaceans and rainbow trout

Abstract

AbstractSublethal responses of the fish Oncorhynchus mykiss, Galaxias maculatus, Pseudaphritis urvillii, and the crustacean Paratya australiensis to short‐term exposures to low concentrations of seven pesticides were compared under identical conditions. Parameters examined were hematocrit, leucocrit, plasma glucose, plasma protein, plasma chloride, muscle RNA and DNA, brain and muscle acetylcholinesterase activity, hepatic glutathione‐S‐transferase activity, hepatic glutathione, and somatic growth. The organisms were exposed to the following materials–the organophosphate insecticides acephate and fenitrothion; the phenoxyacetate herbicide MCPA‐Na; the triazine herbicides atrazine and cyanazine; the fungicide chlorothalonil, and the pyrethroid insecticide cypermethrin–as purified active ingredients in continuous flow through at constant temperature (12–15°C) for 10 or 20 d, with feeding, at five concentrations. Oncorhynchus mykiss was marginally the most sensitive fish species studied in terms of the number of responses to pesticide exposure, but not in terms of the LOECs. Interspecies comparisons indicated that water quality criteria based on juvenile Oncorhynchus mykiss toxicity data alone would not be suitable for the protection of juvenile and adult Galaxias maculatus and Pseudaphritis urvillii from physiological stress in at least three of seven cases. Four of seven maximum acceptable toxicant concentrations (MATCs) derived from physiological responses of fish species resulted from data on Galaxias maculatus and Pseudaphritis urvillii alone. In the case of organophosphates, the decapod crustaceans Paratya australiensis and Astacopsis gouldi were by far the most sensitive. Tentative water quality criteria for the protection of study species from short‐term stress are proposed.