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

## TL;DR

This review explores how nanoplastics harm fish sperm quality, affecting motility, viability, and reproduction, with potential long-term impacts on fish populations.

## Contribution

The paper provides a comprehensive synthesis of nanoplastic effects on fish sperm, emphasizing gaps in understanding and transgenerational risks.

## Key findings

- Nanoplastics consistently impair sperm motility, viability, and fertilization capacity in fish.
- Exposure to nanoplastics causes oxidative stress, DNA damage, and mitochondrial dysfunction in fish sperm.
- Nanoplastics can lead to reduced offspring survival and disrupted gene expression in fish.

## Abstract

Nanoplastics (NPs) are increasingly present in aquatic environments and are small enough to interact directly with biological cells. Fish sperm are particularly vulnerable because they are released directly into the water during fertilization and have limited protective and repair mechanisms. This review summarizes current evidence on how nanoplastics affect fish sperm quality, including motility, viability, fertilization capacity, and underlying cellular mechanisms such as oxidative stress and mitochondrial dysfunction. It also discusses indirect evidence from gonadal, hormonal, and molecular studies, while highlighting the limitations of extrapolating these effects to sperm function. Emerging findings on multigenerational effects and interactions with other environmental stressors are reviewed, emphasizing areas where data remain scarce. Finally, the review outlines key knowledge gaps and discusses the relevance of nanoplastic-induced sperm impairment for fish populations and aquaculture, where sperm quality is critical for hatchery success. Overall, this work highlights the need for more targeted, environmentally relevant studies focusing on sperm-specific endpoints.

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.