Ecotoxicological assessment of emerging pollutants and diatom vulnerability in aquatic ecosystems

Diatoms are photosynthetic, silica-shelled microalgae that make up around 20% of the world’s primary production and are sensitive markers of the health of aquatic ecosystems. Emerging pollutants (Eps) like pesticides, PFAS, micro- and nanoplastics, personal care products, and pharmaceuticals are posing a growing threat to their physiological and ecological functions. This review highlights research gaps, summarizes current understanding of EP impacts on diatom biodiversity and ecosystem services, and suggests integrated monitoring and mitigation techniques. We examine EP classes, exposure pathways, molecular effects, and ecological outcomes using evidence from over 150 ecotoxicological studies and field data from the Umiam Reservoir (Meghalaya). Climate stressors amplify the impacts of EPs, which alter community composition, reduce biodiversity, and hinder nutrient cycling. Long-term, low-dose, and combination exposures also disrupt diatom photosynthesis, silica shell production, gene expression, and population dynamics. Although there are still financial and environmental barriers, O3/UV advanced oxidation technologies, algal–bacterial reactors, and artificial wetlands offer partial rehabilitation. Diatom-specific measurements and mixing criteria are frequently absent from regulatory frameworks. Transformation products, combination toxicity under low-dose and chronic exposures, and interactions with climatic factors are among the main areas of unknown information. Effect-directed analysis, omics-based biomarkers, and real-time monitoring using machine learning are future objectives. For early detection, community tools like smartphone microscopy should be improved. In order to develop pollution-resilient aquatic systems and conserve diatom variety in the face of climate change, interdisciplinary approaches combining ecological modeling, precise analytics, green technology, and inclusive policy are needed.