MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14822

ABSTRACT: Despite increasing evidence of adverse effects of titanium dioxide nanoparticles (nTiO₂) on various biological processes, its impacts on many aquatic ecosystems, where nTiO₂ pollution is steadily increasing, remain largely unknown. For aquatic organisms with external fertilisation, reproductive stages are likely to be especially vulnerable to nTiO₂ toxicity, given that gametes and developing embryos are directly exposed to contaminants. Here, we investigate the effects of the rutile crystalline form of nTiO₂ at environmentally relevant concentrations of 5, 10 and 50 μg L^-1 on reproduction in the sea urchin Heliocidaris erythrogramma armigera. We examine the key motility traits of sperm using computer-assisted sperm analysis (CASA) and assess fertilisation rates after exposure of gametes to nTiO₂. Furthermore, we examine embryo survival in two distinct exposures to discern whether exposure of sperm to nTiO₂ prior to fertilisation or direct exposure of the developing embryos to nTiO₂ affects embryo survival. We find no significant effect of nTiO₂ on sperm motility, fertilisation success, and embryo survival when embryos are directly exposed to nTiO₂. However, embryo survival is reduced when sperm has been exposed to nTiO₂ prior to fertilisation, highlighting the need for an extended assessment of the risk of nTiO₂ for this and other broadcast spawning species.