Behavioural incongruities in juvenile Cyprinus carpio exposed to organophosphate compounds

For the ever increasing human population, the necessity to produce the food in large quantities has become the main goal internationally which has led to increase the practice of pesticides globally. Presence of pesticides in aquatic water bodies is largely due to the runoff from agricultural fields causing to deteriorate the healthy characteristics of an aquatic environment system leading to the toxic impact on non-target aquatic organism such as fish.

In fish, there are various portal of entry through which the contaminants enter. Via various routes, the contaminants reach into the blood and subsequently to different organs or systems. Since Pesticides are known to modify the behavior of animals when exposed to toxic levels. The behavioral changes may be caused by the changes in the nervous system triggered directly or through metabolic or physiological activities. However, the effects have been found to be multifarious and known to differ at different concentrations. Also, Blood is the most accessible component of the vertebrate body fluid system and consequences of direct and indirect damage to blood cells and their precursors are predictable and potentially life threatening. Therefore, behavioural and genotoxicological studies have been considered and used as diagnostic tool in order to investigate behavioural and genotoxicological alterations. This study was undertaken to investigate behavioural changes in Cyprinus carpio exposed to two organophosphate compounds, chlorpyrifos (cpf) and dimethoate (dim). Fishes weighing 10 ± 2 g were exposed to sub-lethal concentrations of cpf (0.76 ppb, 1.52 ppb, 2.28 ppb, 3.04 ppb and 3.8 ppb) and dimethoate (0.22 ppm, 0.44 ppm, 0.66 ppm, 0.88 ppm and 1.1 ppm) for the period of 96 h and various behavioural indices were evaluated during that period. Both the pesticides were found to induce behavioral toxicity in fishes such as drop in swimming velocity, reduced swimming activity and retarded opercular movements. Cpf was found more detrimental as compared to dimethoate in all cases. Fishes also elicited a genotoxic response which was evaluated by calculating the frequency of micronuclei formation in their hematocytes after 21 days of exposure. Chlorpyrifos induced more genotoxicity than dimethoate which was found dose and time dependent.

It was concluded that the behavioural and genotoxic alterations in common carp could be applied as possible biomarkers in risk assessment and monitoring programs for pesticide contamination of aquatic ecosystems.

This study is one of its kind and will help to form baseline data.