The Impact of Nanoplastics on the Quality of Fish Sperm: A Review.

Pollution in aquatic ecosystems is intensifying under the combined pressures of climate change and anthropogenic contaminants, with nanoplastics (NPs) emerging as a critical threat to fish reproduction. Although extensive research has demonstrated the physiological impacts of NPs, their direct effects on sperm quality and functionality remain poorly characterized. This review synthesizes evidence from original research articles that specifically examined NPs' impacts on fish sperm quality and related reproductive endpoints. The findings reveal that NPs consistently impair sperm motility, viability, and fertilization capacity, while inducing oxidative stress, DNA damage, mitochondrial dysfunction, and endocrine disruption. Particle size, surface chemistry, and exposure route were identified as key determinants of toxicity, with direct sperm exposure causing immediate impairments and chronic or maternal transfer exposures leading to systemic and transgenerational effects. Notably, several studies reported reduced offspring survival, altered development, and disrupted gene expression, highlighting the intergenerational risks of NPs contamination. Despite these advances, significant knowledge gaps remain, including limited research on marine wild and cultured fish species, the effects of diverse life histories on NPs toxicity, environmentally relevant exposure levels, and the combined effects of NPs with other stressors. Overall, this review underscores that fish sperm are highly sensitive to NPs pollution, with consequences that extend across generations and threaten population stability, calling for urgent mechanistic and ecologically realistic investigations.