Organophosphate, Carbamate and Synthetic Pyrethroid Pesticide Residues in Muscle Tissues of Fish from Loktak Lake, a Ramsar Site in Manipur, India

The muscle tissues of Channa punctatus and Anabas testudineus collected from the Loktak Lake (a Ramsar site) and its three major feeder rivers in Manipur, Northeastern India, were analyzed using high-performance liquid chromatography for the presence of residues of three organophosphorus (malathion, dichlorvos and monocrotophos), one carbamate (carbofuran), and two synthetic pyrethroid (deltamethrin and cypermethrin) pesticides. Residues of all the pesticides except monocrotophos were detected in the fish tissues. Among the five pesticides detected, concentrations of dichlorvos exceeded the maximum residue limit (MRL) prescribed by the Codex Alimentarius for animal tissues such as mammalian offal, eggs and poultry meat. The rest of the compounds were within the MRL for eggs and animal tissues. None of the pesticide residues was detected in the two fish species collected from the control or reference site. The present study indicates that pesticide contamination is emerging as a threat to the water quality and aquatic biodiversity of Loktak Lake, which is a “wetland of international importance” (Ramsar Site) located in a global biodiversity hotspot. The findings of this study also calls for more detailed investigations on the presence of pesticide residues in water, sediments, aquatic macrophytes, planktonic and benthic organisms, and different fish species of this wetland ecosystem.