Assessment of pesticide contaminated sediment using biological response of tropical chironomid,Chironomus javanus Kiffer as biomarker

Objective: To investigate the use of a biomarker for assessment of the effects on the tropical chironomid, Chironomus javanus（C. javanus）, Kiffer of sediment contaminated with an insecticide（chlorpyrifos）.Methods: A wide range of biological responses to the tropical chironomid exposed were measured, including survival, growth rate and Acetylcholinesterase（AChE） activity.Results: The measured median lethal concentration(96 h LC50) of chlorpyrifos to C. javanus was 0.056（95% CI 0.024-0.124）μg/kg. For sub-chronic levels of chlorpyrifos between 0.001 and 0.25μg/kg administered for 10 days, the effects on the growth of C. javanus were reduced（larva size, head structure width and dry weight） at the significance level（P<0.01） and the effects were concentration dependent. Following exposure to chlorpyrifos at the level of 0.001μg/kg for 48 and 96 h, the AChE activity in C. javanus was inhibited compared with control samples（P<0.05）.Conclusions: This study demonstrated that C. javanus was sensitive when exposed to chlorpyrifos. This species could serve as a potential biomarker for assessing pesticide contamination at low environmental persistence and provides limited effects data on the sensitivity of tropical biota to contaminants for ecological risk assessment of organophosphate pesticides in the tropical aquatic ecosystem.