Ensuring that oocytes are fertilized by a single sperm during broadcast spawning is crucial for the fertilization success of many marine invertebrates. Although the adverse impacts of ocean acidification (OA) on various marine species have been revealed in recent years, its impact on polyspermy and the underlying mechanisms involved remain largely unknown. Therefore, in the present study, the effect of OA on polyspermy risk was assessed in a broadcast spawning bivalve, Tegillarca granosa. In addition, the impacts of OA on the two polyspermy blocking processes, the fast block (membrane depolarization) and the permanent block (cortical reaction), were investigated. The results show that the exposure of oocytes to two future OA scenarios (pH 7.8 and pH 7.4) leads to significant increases in polyspermy risk, about 1.70 and 2.38 times higher than the control, respectively. The maximum change in the membrane potential during oocyte membrane depolarization markedly decreased to 15.79 % (pH 7.8) and 34.06 % (pH 7.4) of the control value. Moreover, the duration of oocyte membrane depolarization was significantly reduced to approximately 63.38 % (pH 7.8) and 21.91 % (pH 7.4) of the control. In addition, cortical granule exocytosis, as well as microfilament migration, were significantly arrested by OA treatment. Exposure to future OA scenarios also led to significant reductions in the ATP and Ca²⁺ content of the oocytes, which may explain the hampered polyspermy blocking. Overall, the present study suggests that OA may significantly increase polyspermy risk in T. granosa by inhibiting membrane depolarization and arresting cortical granule exocytosis.

确保卵在繁殖产卵时受单个精子受精对于许多海洋无脊椎动物的受精成功至关重要。尽管近年来已经发现了海洋酸化（OA）对各种海洋物种的不利影响，但是其对多精子的影响及其所涉及的潜在机制仍然未知。因此，在本研究中，在广播产卵双壳类Tegillarca granosa中评估了OA对多精子风险的影响。。另外，研究了OA对两个多精子阻断过程（快速阻断（膜去极化）和永久阻断（皮层反应））的影响。结果表明，将卵母细胞暴露于两种未来的OA情景（pH 7.8和pH 7.4）会导致多精子风险的显着增加，分别比对照组高1.70倍和2.38倍。卵母细胞膜去极化过程中膜电位的最大变化显着降低至对照值的15.79％（pH 7.8）和34.06％（pH 7.4）。此外，卵母细胞膜去极化的持续时间显着减少至对照的约63.38％（pH 7.8）和21.91％（pH 7.4）。此外，OA治疗可显着阻止皮质颗粒的胞吐作用以及微丝迁移。卵母细胞的²⁺含量，可能解释了阻碍的多精子阻滞。总体而言，本研究表明，OA可能通过抑制膜去极化并阻止皮质颗粒的胞吐作用而显着增加颗粒状线虫的多精子症风险。