Seawater carbonate chemistry and sperm swimming speed of the polychaete Galeolaria caespitosa in lab experiment

The rapidity of ocean acidification intensifies selection pressure for resilient phenotypes, particularly during sensitive early life stages. The scope for selection is greater in species with greater within-species variation in responses to changing environments, thus enhancing the potential for adaptation. We investigated among-male variation in sperm swimming responses (percent motility and swimming speeds) of the serpulid polychaete Galeolaria caespitosa to near- (delta pH 0.3) and far-future ocean acidification (delta pH 0.5). Responses of sperm swimming to acidification varied significantly among males and were overall negative. Robust sperm swimming behavior under near-future ocean acidification in some males may ameliorate climate change impacts, if traits associated with robustness are heritable, and thereby enhance the potential for adaptation to far-future conditions. Reduced sperm swimming in the majority of male G. caespitosa may decrease their fertilization success in a high CO2 future ocean. Resultant changes in offspring production could affect recruitment success and population fitness downstream.

海洋酸化的快速发展加剧了对耐受性表型（resilient phenotypes）的选择压力，尤其作用于生物敏感的早期生命阶段。对环境变化响应存在更大种内变异的物种，其选择作用的范围更广，由此提升了物种的适应潜能。本研究针对龙介虫多毛类（serpulid polychaete）盖氏盘管虫（Galeolaria caespitosa）展开实验，探究其雄性个体间的精子游泳响应差异，检测指标包括精子运动百分率与游泳速度，分析该物种对近期未来（pH变化量ΔpH 0.3）与远期未来（pH变化量ΔpH 0.5）海洋酸化的响应情况。不同雄性个体的精子游泳行为对酸化的响应存在显著差异，且整体呈现负面效应。若与耐受性相关的性状可遗传，那么部分雄性个体在近期未来海洋酸化环境下仍能维持稳健的精子游泳行为，这或许能够缓解气候变化带来的负面影响，进而提升物种适应远期未来酸化环境的潜能。多数盖氏盘管虫雄性个体的精子游泳能力出现下降，这可能会使其在未来高CO₂海洋环境中的受精成功率降低。由此引发的后代产出变化，可能会进一步影响种群后续的补充成功与种群适合度。