Toxicity of chlorpyrifos on some marine cyanobacteria species

Pakistan is an agricultural country and a wide variety of pesticides are used on its cropland. pesticides pose serious threats to the natural ecosystem. in the present study cyanobacteria (blue green algae) were used to assess the ecotoxicological effect of chlorpyrifos (organophosphate pesticide). cyanobacteria are the base of the food web providing food resource to consumers in higher trophic level. cyanobacteria were isolated and purified from water samples collected from manora channel. fast growing cultures of cyanobacteria were used to assess the toxicity of test pesticide. the light and dark method was used to determine the primary production of the organisms. the acute toxicity of chlorpyrifos was determined by calculating ic50 of the test organisms. the ic50 was found to be 0.074,0.013,0.08 and 0.3 ppm for synechocystis aquatilis,komvophoron minutum,gloeocapsa crepidinum and gloeocapsa sanguinea when exposed to chlorpyrifos pesticide. laboratory experiments with cyanobacteria have demonstrated that organophosphate pesticides are potent inhibitors of photosynthesis.