The effects of Triclosan (TCS) on the survival, serum biomarkers, antioxidant defense, and apoptosis of mud crab (Scylla paramamosain)

Triclosan (TCS), a widely used antimicrobial agent, is known to have toxic effects on aquatic organisms, potentially disrupting reproduction, development, and behavior. However, its impact on marine invertebrates, particularly crustaceans, remains understudied. To evaluate the effects of TCS, juvenile mud crabs ( Scylla paramamosain ) were exposed to TCS concentrations ranging from 50 to 5000 μg/L over a 96-hour period in this study. Results showed that low TCS concentrations had no significant short-term effects on the crabs, whereas moderate to high concentrations caused disruptions in hemolymph parameters, increased oxidative stress, and reduced antioxidant enzyme activity, ultimately leading to mortality. Exposure to these higher concentrations also led to the upregulation of heat shock proteins (HSPs) and antioxidant enzyme mRNA expression as part of the stress response, alongside the increased expression of pro-apoptotic genes and suppression of anti-apoptotic genes. The effects were generally similar between sexes, although females showed greater susceptibility than males. Additionally, TCS exposure altered serum cholesterol levels in females but had no effect on males, suggesting a possible estrogenic effect of TCS that requires further investigation. This study provides important data for assessing the risks of TCS in aquatic environments and has significant implications for the conservation of estuarine ecosystems and fisheries resources. • The study examines the effects of triclosan (TCS) on juvenile mud crabs, highlighting its potential harm to marine crustaceans. • Low TCS levels had no significant impact, but moderate to high levels caused physiological and biochemical stress, leading to crab mortality. • High TCS levels induced stress response proteins and altered gene expression related to apoptosis. • Female crabs were more susceptible to TCS effects, with changes in cholesterol levels suggesting a possible estrogenic effect. • The findings underscore the need for caution with TCS use and have implications for protecting aquatic ecosystems and fisheries.