Integrated Use of Biomarkers (O : N Ratio and Acetylcholinesterase Inhibition) on Aulacomya ater (Molina, 1782) (Bivalvia: Mytilidae) as a Criteria for Effects of Organophosphate Pesticide Exposition

Abstract

The effect of residual concentrations of organophosphate pesticide chlorpyrifos (Lorsban 4E) on the activity of the acetylcholinesterase enzyme and oxygen : nitrogen ratio in the mussel Aulacomya ater was analyzed. Toxicity tests show a sensitivity to the pesticide in the bivalve estimated at 16 μg L(-1) (LC(50-96 hours)). Concentrations between 0.2 and 1.61 μg L(-1) were able to inhibit significantly the AChE activity, and concentrations between 0.8 and 1.61 μg L(-1) stimulate ammonia excretion and decrease oxygen : ammonia-N (O : N) ratio, with respect to the control group. A. ater proved to be a species sensitive to pesticide exposure and easy to handle in lab conditions. Thus, it is recommended as a bioindicator for use in programs of environmental alertness in the Eastern South Pacific coastal zone.

Figure 1

AChE activity in Aulacomya ater exposed to grow sublethal concentrations of organophosphate pesticide Lorsban 4E for 21 days. Mean values with standard error plotted (*statistical difference P < 0.05).

Figure 2

Oxygen uptake of Aulacomya ater in control and exposed grow sublethal concentrations of organophosphate pesticide. Mean values with standard error plotted.

Figure 3

Ammonia excretion on Aulacomya ater in control and exposed sublethal concentrations of organophosphate pesticide. Mean values with standard error plotted (*statistical difference P < 0.05).

Figure 4

O : N ratio in Aulacomya ater exposed to grow sublethal concentrations of organophosphate pesticide Lorsban 4E and control group. Mean values with standard error plotted (*statistical difference P < 0.05).