Determination of changes in

Toxic stress caused by pesticides changes the function and structure of the aquatic ecosystem via impressing to species composition. Therefore it is necessary to determine the reaction of cyanobacteria to pesticides for comprehend the effects of these substances on the aquatic ecosystems. This study aims to determine the toxicity and oxidative stress that Lambda cyhalothrin may cause in cyanobacteria, one of the primary producers in lake ecosystems. For these reasons, the changes in chlorophyll-a content, OD560 absorbance, the antioxidant enzyme acitvities such as superoxidedismutase (SOD), ascorbate peroxidase (APX), and glutathione reducatse (GR) were assessed to carry out the effect of Lambda cyhalothrin concentrations (between 6.25 and 100 μg ml−1) on Arthrospira platensis. EC50 value is calculated as 11.94 μg m l−1 Lambda cyhalothrin concentrations. SOD and APX activities was statistically different from the control at 100 μg m l−1 Lambda cyhalothrin application compared to control in A. platensis-M2 cells. On the other hand, GR activity did not effect significantly. According to our results, we may conclude that Lambda cyhalothrin concentrations used in this study inhibited the growth of A. platensis cells in a time and dose-dependent manner, as indicated by lowered chlorophyll-a content and OD560 values and Lambda cyhalothrin caused oxidative stress in A. platensis cells. As a result, the restriction of Lambda cyhalothrin using at the certain concentrations may be a step to prevent pesticide pollution in the environment.This study aims to determine the toxicity of Lambda cyhalothrin may cause in cyanobacteria, one of the primary producers in lake ecosystems. According to our results, we may conclude that Lambda cyhalothrin inhibited the growth of A. platensis and it caused oxidative stress in the organism