Elevated CO2 affects embryonic development and larval phototaxis in a temperate marine fish

As an effect of anthropogenic CO2 emissions, the chemistry of the world's oceans is changing. Understanding how this will affect marine organisms and ecosystems are critical in predicting the impacts of this ongoing ocean acidification. Work on coral reef fishes has revealed dramatic effects of elevated oceanic CO2 on sensory responses and behavior. Such effects may be widespread but have almost exclusively been tested on tropical reef fishes. Here we test the effects elevated CO2 has on the reproduction and early life history stages of a temperate coastal goby with paternal care by allowing goby pairs to reproduce naturally in an aquarium with either elevated (ca 1400 µatm) CO2 or control seawater (ca 370 µatm CO2). Elevated CO2 did not affect the occurrence of spawning nor clutch size, but increased embryonic abnormalities and egg loss. Moreover, we found that elevated CO2 significantly affected the phototactic response of newly hatched larvae. Phototaxis is a vision-related fundamental behavior of many marine fishes, but has never before been tested in the context of ocean acidification. Our findings suggest that ocean acidification affects embryonic development and sensory responses in temperate fishes, with potentially important implications for fish recruitment.

受人为二氧化碳排放影响，全球海洋的化学环境正发生改变。厘清该变化对海洋生物与生态系统的作用机制，对预测当前持续发生的海洋酸化（ocean acidification）所造成的影响至关重要。此前针对珊瑚礁鱼类的研究已揭示，海洋二氧化碳浓度升高会对其感官反应与行为产生显著影响。此类影响或具有普遍性，但目前几乎仅在热带珊瑚礁鱼类中得到检验。本研究以一种具备父本抚育（paternal care）行为的温带沿海虾虎鱼为对象，探究了二氧化碳浓度升高对其繁殖及早期生活史阶段的影响：我们让虾虎鱼配对在分别设置了高浓度二氧化碳（约1400 µatm）与对照水平二氧化碳（约370 µatm）的水族箱中自然繁殖。结果显示，二氧化碳浓度升高未对产卵行为与产卵量产生显著影响，但显著提升了胚胎畸形率与卵损失率。此外，本研究还发现，二氧化碳浓度升高会显著改变新孵化幼体的趋光反应。趋光性（phototaxis）是多数海洋鱼类依赖视觉的基础行为之一，但此前从未在海洋酸化的研究背景下开展过相关测试。本研究结果表明，海洋酸化会对温带鱼类的胚胎发育与感官反应造成影响，这对鱼类种群补充可能具有重要意义。