Emerging Environmental Toxicants Undermine Reproductive Success in Aquatic Animals: A Narrative Review.

Aquatic animals are increasingly exposed to complex mixtures of emerging environmental toxicants, including microplastics, nanoplastics, per- and polyfluoroalkyl substances (PFAS), and endocrine-disrupting chemicals (EDCs). This raises serious concerns for reproductive health, offspring survival rates, and long-term population stability. This narrative review synthesizes the available peer-reviewed evidence on the reproductive and developmental effects of these contaminant groups in aquatic animals. Growing evidence indicates that these contaminants adversely affect reproductive processes, impair offspring development, and reduce survival and fitness across a wide range of aquatic species. Their effects are mediated through interconnected pathways involving oxidative stress, endocrine disruption, inflammation, mitochondrial dysfunction, and epigenetic alterations, ultimately leading to reproductive and developmental abnormalities. These changes may weaken wild fish populations, reduce aquaculture productivity, and compromise aquatic biodiversity. However, interpretation of the available evidence is constrained by substantial heterogeneity in species, contaminant properties and concentrations, exposure durations, and reproductive endpoints, together with the predominance of laboratory-based single-contaminant studies. This review integrates current knowledge on the reproductive and developmental impacts of emerging contaminants by connecting mechanistic toxicity pathways with population-level and ecosystem consequences. Overall, this review emphasizes that protecting aquatic reproductive health requires an integrated framework linking contaminant monitoring, mechanistic biomarkers, reproductive performance, and ecosystem-level risk assessment.