Investigation of acute toxicity of chlorpyrifos-ethyl on Clarias gariepinus – (Burchell, 1822) using some behavioural indices

Abstract

The impact of short-term exposure to waterborne chlorpyrifos-ethyl on Clarias gariepinus was evaluated through changes of selected behavioural parameters. Fish was exposed to 0.64 mg/l, 0.80 mg/l, 0.96 mg/l, 0.12 mg/l, 0.28 mg/l and control for 96h. The parameters measured were Opercular ventilation (OVC), Tail fin movement rate (TMR), Air gulping index (AGI) and Mortality. The main effects of concentration and duration on rates of tail fin movement rate of fish were highly significant (p<0.001). There was significant decrease (p<0.05) in the opercular ventilation of treated fish when compared with control. Also both the main effects of concentration and duration of exposure of chlorpyrifosethyl and the effect of their interactions on AGI were highly significant (p<0.001). Highest mortality was recorded from 1-12hrs period of exposure and the mortality at 12hrs was significantly (P<0.05) higher than the mortality recorded from 24hrs-96hrs periods. The acute toxicity of chlorpyrifos-ethyl elicited dose and duration dependent behavioural changes that led to mortality of fish. Behavioural changes were therefore proven to be more sensitive endpoints than mortality.

Behavioural and Some Physiological Assessment of Glyphosate and Paraquat Toxicity to Juveniles of African Catfish, Clarias gariepinus

“…The AGI significantly reduced after 48 h, which may suggest physical fatigue due to swimming and other cumulative physiological effects of the toxicants. This scenario was also reported by Ogueji et al (2013).…”

“…Opercular movement reduced by the 24 th h which probably means that the fish are gradually coping to the new environment, trying to overcome the initial shock/harsh condition. A similar explanation may probably suffice for the increase in tail movement rate by the 12 th h and reduction by the 24 th h. Ogueji et al (2013) reported that surviving fish was maximally intoxicated at this period due to maximum bioconcentration and bioaccumulation. Also, the marked increase in opercular ventilation and tail fin beats per minute may be that the exposed fish needed more oxygen for the increased metabolic rate especially within 12 h of exposure.…”

Behavioural Responses and Mortality of Clarias gariepinus Juveniles Exposed to Acute Concentrations of Paraquat

“…No such pattern was observed for fish in the control tanks. The observed behavioural pattern in this study are consistent with previous reports with some herbicides [7,11,14,16]. Besch [24] reported that fish exposed to toxicants is characterized by the behavioural phases such as contact (high excitability in a moment), exertion (fast swimming, leaping and attempts to jump out of the toxicant), equilibrium (instability) and death (lack of response to external stimulus).…”

“…Although herbicides are designed to control plant pests by inhibiting photosynthesis but significantly large concentrations can be toxic to animal through necrosis [6]. Direct and indirect contamination of aquatic environment with pesticides may cause fish kills, reduce fish productivity and elevates concentration of undesirable chemicals in edible fish tissues [7]. It is imperative to find out the detrimental effects of pollutants especially herbicides on fish since they form important food chain.…”

Acute toxicity of glyphosate and paraquat to the African catfish (Clarias gariepinus, Teugels 1986) using some biochemical indicators

“…Conveniently, aquatic organisms (fishes) may serve as bioindicators of the environmental status of their habitats. Since they often respond to low concentrations of environmental contaminants, they may serve as good candidates for toxicity assays (Davies and Vethaak 2012;Ogueji et al 2013).…”