Fertilisation and larval development in an Antarctic bivalve, Laternula elliptica, under reduced pH and elevated temperatures@en

Elevated temperatures associated with ocean warming and acidification can influence development and, ultimately, success of larval molluscs. The effect of projected oceanic changes on fertilisation and larval development in an Antarctic bivalve, Laternula elliptica, was investigated through successive larval stages at ambient temperature and pH conditions (-1.6°C and pH 7.98) and conditions representative of projections through to 2100 (-0.5°C to +0.4°C and pH 7.80 to pH 7.65). Where significant effects were detected, increased temperature had a consistently positive influence on larval development, regardless of pH level, while effects of reduced pH varied with larval stage and incubation temperature. Fertilisation was high and largely independent of stressors, with no loss of gamete viability. Mortality was unaffected at all development stages under experimental conditions. Elevated temperatures reduced occurrences of abnormalities in D-larvae and accelerated larval development through late veliger and D-larval stages, with D-larvae occurring 5 d sooner at 0.4°C compared to ambient temperature. Reduced pH did not affect occurrences of abnormalities in larvae, but it slowed the development of calcifying stages. More work is required to investigate the effects of developmental delays of the magnitude seen here in order to better determine the ecological relevance of these changes on longer term larval and juvenile success.与海洋增温和酸化相关的升温现象，会影响软体动物幼体的发育进程，并最终影响其生存成功率。本研究以南极双壳类动物椭圆露纹蛤（Laternula elliptica）为研究对象，在环境温度与pH条件（-1.6℃、pH 7.98）以及代表2100年海洋环境变化预测的条件（-0.5℃至+0.4℃、pH 7.80至7.65）下，对其受精过程及幼体各连续发育阶段展开调查，以评估未来海洋环境变化对其受精与幼体发育的影响。在检测到显著影响的实验组中，无论pH水平如何，升温均对幼体发育产生持续的正向作用；而pH降低的影响则随幼体发育阶段与培育温度的不同而有所差异。受精率整体处于较高水平，且基本不受胁迫因子影响，配子活力未出现下降。实验条件下，各发育阶段的幼体死亡率均未受到显著影响。升温可降低D形幼虫的畸形发生率，并加快后期面盘幼虫与D形幼虫阶段的幼体发育速度：在0.4℃条件下，D形幼虫的出现时间较环境温度组提前了5天。pH降低未对幼体畸形发生率产生影响，但会延缓钙化阶段的发育进程。为进一步明确此类发育延迟现象的生态相关性，及其对幼体与稚贝长期生存成功率的影响，仍需开展更多相关研究。