Fluoxetine impairs gamete function and fertilization success in Tegillarca granosa: environmental risks of antidepressant contamination

In recent years, the antidepressant fluoxetine (FLX) has been increasingly detected in global environments, emerging as a contaminant with significant toxic effects. However, its impact on the fertilization processes of broadcast-spawning species remains unclear. This study focuses on Tegillarca granosa, a broadcast-spawning bivalve, to evaluate the effects of fluoxetine on gametes and fertilization success. The findings revealed that FLX significantly reduced sperm motility, including curvilinear velocity, average path velocity, and straight-line velocity. Further analysis demonstrated that FLX impaired sperm motility by inhibiting ATP production and reducing cellular activity. Additionally, FLX altered Ca²⁺ homeostasis and caspase activity in both sperm and eggs, and suppressed mitochondrial energy supply in eggs. By assessing gamete collision probabilities and fusion rates, the study systematically confirms the considerable fertilization toxicity of FLX in T. granosa. These findings provide critical insights into the environmental risks posed by FLX contamination.