Anodonta cygnea, a freshwater swan mussel, exposed to diazinon: toxicity thresholds in behaviour and physiology

Swan mussels (Anodonta cygnea) have been suggested as suitable bioindicators for the presence of pollutants in the environ-ment. Application of the physiological and behavioral markers in these sessile species can be beneficial for environmentalmonitoring. The present study aimed to investigate the relationship between the behavioral disorders of movement andsiphoning associated with the inhibition of tissue Acetylcholinesterase (AChE). For experiments, overally 120 bivalves ofAnodonta cygnea (mean total length 80.33 ± 6.7 mm) were transported from the agricultural drains and canals in Sari county(Mazandaran Province, Iran) to our laboratory. First, the LC50-96 h of diazinon was estimated according to the Organizationfor Economic Co-operation and Development (OECD 1992) guideline with static water conditions. The sub-lethal toxicitypesticide experiments were conducted on the basis of the lowest observed effect concentration (LOEC) and the maximumacceptable toxicant concentration (MATC). The LC50-96 h, LOEC, and MATC values of diazinon were 85.2, 42.1, and8.5 mg L− 1, respectively. Based on the observations of mussels’ movement, the burrowing and displacement decreased withthe concentration of toxicant in water. Moreover, the presence of diazinon in water and its exposure to experimental animalssignificantly reduces their siphoning rate. The RDA showed that the AChE activity had a higher correlation with the siphoningbehavior than the movement behavior. The comparison of enzyme activity at different exposure and recovery times showedthat there was a significant difference among the groups affected by the consumed pesticide (p = 0.001, between contrasts).The most remarkable morphometric characteristic was the siphon opening that was inversely correlated with the enzymaticactivity. Studies in bioethics might benefit from paying attention to these traits that are directly related to the level of toxicityand behavioral adaptations required for animal survival. (PDF) Anodonta cygnea, a freshwater swan mussel, exposed to diazinon: toxicity thresholds in behaviour and physiology. Available from: https://www.researchgate.net/publication/368423946_Anodonta_cygnea_a_freshwater_swan_mussel_exposed_to_diazinon_toxicity_thresholds_in_behaviour_and_physiology#fullTextFileContent [accessed Feb 12 2025].