Physiological Effect of Organic Phosphorus Insecticides on Several Species of Fish

Abstract

Fish brain acetylcholinesterase is inhibited in vlvo by organic phosphorus insecticides at concentrations of 0.1 rag/1 and lower. The degree of inhibition is a function of the concentration of the insecticide, the extent of exposure, specific chemical nature of the inhibiting substance, and fish species. Species used were largemouth bass (Micropterus salmoides), bluegill (Lepomis macrochirus), golden shiner (Notemigonus crysoleucas), goldfish (Carassius auratus), and fathead minnow (Pimephales promelas). Fish removed from exposure to acetylcholinesterase-inhibiting insecticides, prior to reaching lethal limits, demonstrate the capacity for regeneration of this enzyme. The time required to regenerate the brain acetylcholinesterase to normal levels depends on the extent of the initial inhibition, the specific nature of the compound producing the inhibition, and the particular species. The curve of brain enzyme inactivation and recovery, as defined by percentage changes in normal activity, describes a physiological brain cholinesterase characteristic of the fish species. The period necessary to regenerate to normal activity may be longer than 30 days. By utilization of suitable fish species it is possible to demonstrate the presence of organic phosphorus insecticides in water at concentrations of 0.1 rag/1 with exposure periods of 12 to 24 hours. Some compounds produce marked inhibition of brain enzyme activity in 6 hours. At 0.01 mg/l Guthion produces comparable in vivo inhibition of brain acetylcholinesterase in 12 hours' exposure in several species.

Factors affecting cholinesterase activity in aquatic animals

“…This result agrees with results of similar comparisons in the literature (Weiss, 1961;Rath and Misra, 1980;ZinkI et al, 1987). In any monitoring using ChE activity, similarly-sized organisms should be used.…”

“…1961). Most of the variation occurred in the smallest fish; adult fish did not vary much in brain ChE activity with brain weight (Weiss, 1961). In tilapia fTiiaoia mossambicaV a strongly negative, linear correlation was found between body weight and both brain and liver ChE activity (Rath and Misra, 1980).…”

“…Farming is a common activity along the upper Mississippi River (UMR), and contamination of the river by the most commonly used herbicides has been documented (Thurman et al, 1992 inhibitors (Weiss, 1961;Weiss and Gakstatter, 1964; Eaton, 1970; Maceket a!., 1972; Vittozzi and De Angelis, 1991; Richmonds and Dutta, 1992; Tanner and Knuth, 1995), and have been found to be highly sensitive to OPs in comparison to other fish species (Mayer and Ellersieck, 1986; Vittozzi and De Angelis, 1991 demonstrated that storage at -20°C and below will maintain ChE activity over a period of several weeks Cole, 1995).…”

“…For monitoring potential contamination by ChE-inhibiting pesticides in the UMR, a logical choice is the bluegill sunfish (Leoomis macrochirus). Not only are there abundant bluegill populations throughout the Mississippi River (Fremling et al, 1989), but bluegill have often been used in laboratory and field studies of ChE inhibitors (Weiss, 1961;Weiss and Gakstatter, 1964;Eaton, 1970;Maceket a!., 1972;Vittozzi and De Angelis, 1991;Richmonds and Dutta, 1992;Tanner and Knuth, 1995), and have been found to be highly sensitive to OPs in comparison to other fish species (Mayer and Ellersieck, 1986;Vittozzi and De Angelis, 1991).…”

“…ChE activity is often greater in younger, smaller organisms than in older, larger ones (Weiss, 1961;Rath and Misra, 1980;ZinkI et al, 1987;Gard and Hooper, 1993; Fishwick et al, 1996). Serum and whole body ChE activity has been shown to vary by sex and reproductive status in birds and fish, though the direction of variation differs among species (van der Wei and Welling, 1989;; in contrast, no difference in brain ChE activity has been found by sex or reproductive status in birds or fish studied so far (Hogan, 1970; Coppage, 1972;.…”