Ecological effects of chemical contaminants on sub-tropical aquatic ecosystems

Summary

Freshwater ecosystems are increasingly exposed to chemical contaminants, many of which persist in the environment and pose risks to biodiversity. Most ecotoxicological data used to establish safety thresholds for these chemicals are derived from temperate regions, raising concerns about their applicability to (sub-)tropical ecosystems. My research assessed the ecological effects of three common contaminants, including lambda-cyhalothrin, ciprofloxacin, and triclosan, on sub-tropical freshwater communities using outdoor mesocosm experiments under realistic climatic conditions. The results showed compound-specific effects, often at concentrations that differed from those reported in temperate studies, suggesting potential climate-dependent sensitivities. Environmental DNA metabarcoding, applied alongside traditional morphology-based identification, provided complementary strengths and enhanced the detection of chemical-induced changes. Overall, these findings highlight the importance of region-specific ecotoxicological assessments and the combined application of molecular and morphological approaches to improve ecological risk assessment, thereby informing geographically inclusive strategies for freshwater ecosystem protection.