Effects of different concentrations of nano-titanium dioxide on spawning and progeny development of the bay scallop <i>Argopecten irradians</i>

ABSTRACT Objective We sought to investigate the effects of different concentrations of titanium dioxide nanoparticles (nano-TiO2 [n-TiO2]) on the spawning and subsequent larval development of the bay scallop Argopecten irradians. Methods Bay scallops were exposed to three n-TiO2 concentrations (0.0, 0.1, and 1.0 mg/L) under controlled laboratory conditions. Results The experimental results demonstrated that exposure to n-TiO2 shortened the spawning time in both treatment groups compared to the control group. Higher n-TiO2 concentrations induced a shorter duration required for early embryonic development, although this trend converged to similar timelines at the D-shaped larva stage. Notably, the egg diameter exhibited a significant increase after n-TiO2 exposure during the multicellular stage. Throughout larval development, the shell length and shell height in treated groups were markedly reduced relative to controls at both the D-shaped larva and early umbo larva stages, with a concentration-dependent decline observed as n-TiO2 concentrations increased. This inhibitory effect persisted through the pediveliger larva stage, as the 1.0-mg/L n-TiO2 group showed significantly diminished shell dimensions compared to the 0.1-mg/L n-TiO2 group and the control. Such concentration-dependent morphological suppression continued into adulthood: Adult shell length and height progressively decreased with elevated n-TiO2 concentrations, showing statistically significant differences in the 1.0-mg/L group versus the other treatments. However, no significant morphological distinctions were detected between the 0.0- and 0.1-mg/L n-TiO2 groups across developmental stages. Conclusions This study provides valuable laboratory and field experimental data, offering insights into the acute toxicity and long-term effects of emerging nanomaterials like n-TiO2 on economically important bivalve resources and aquaculture industries.