Alterations induced by titanium dioxide nanoparticles (nano-TiO2) in fertilization and embryonic and larval development of the tropical sea urchin Lytechinus variegatus

The release of nanomaterials into the environment is the cause of an emerging concern. Titanium dioxide nanoparticles (nano-TiO₂) among the most produced nanomaterials, has been documented in marine coastal areas posing a threat on marine biota. Sea urchin embryos are recognized as suitable bioindicators in ecological risk assessment and recently for nanomaterials. This study investigated the impact of nano-TiO₂ on fertilization, embryonic and larval development of the tropical sea urchin Lytechinus variegatus in a range of concentrations (0.005-5 μg/mL) which includes environmentally relevant ones. The behavior of nano-TiO₂ in tropical natural seawater was determined by dynamic light scattering (DLS) and toxicity was evaluated through fertilization and embryotoxicity tests, and morphological/morphometric analyses of sea urchin's larvae. Limited toxicity was recorded for nano-TiO₂ in tropical sea urchin embryos and larvae, except for effects at the gastrula stage at 0.005 μg/mL. Large agglomerates of nano-TiO₂ (5 μg/mL) were observed adhering onto sea urchin larvae thus probably preventing nanoparticles uptake at the highest concentrations (>0.005 μg/mL). Environmental levels of nano-TiO₂ are able to cause toxicity on tropical sea urchin L. variegatus embryos with potential consequences on populations and their ecological role in tropical coastal areas.