Selective mortality associated with variation in CO2 tolerance in a marine fish@en

Predicted future CO2 levels can affect reproduction, growth, and behaviour of many marine organisms. However, the capacity of species to adapt to predicted changes in ocean chemistry is largely unknown. We used a unique field-based experiment to test for differential survival associated with variation in CO2 tolerance in a wild population of coral-reef fishes. Juvenile damselfish exhibited variation in their response to elevated (700 µatm) CO2 when tested in the laboratory and this influenced their behaviour and risk of mortality in the wild. Individuals that were sensitive to elevated CO2 were more active and move further from shelter in natural coral reef habitat and, as a result, mortality from predation was significantly higher compared with individuals from the same treatment that were tolerant of elevated CO2. If individual variation in CO2 tolerance is heritable, this selection of phenotypes tolerant to elevated CO2 could potentially help mitigate the effects of ocean acidification.预测的未来二氧化碳水平，会对诸多海洋生物的繁殖、生长与行为造成影响。然而，当前学界对物种适应预测海洋化学变化的能力仍知之甚少。本研究采用一项独特的野外实地实验，针对珊瑚礁鱼类野生种群中二氧化碳耐受性的个体差异，检验其与存活差异的关联。实验室内测试结果显示，幼体雀鲷对高浓度（700微大气压，µatm）二氧化碳的响应存在个体差异，这一差异会影响它们在野外的行为与死亡风险。对高浓度二氧化碳敏感的个体，在自然珊瑚礁生境中更为活跃，且会远离遮蔽区域；因此，与同一处理组中耐受高浓度二氧化碳的个体相比，这类个体的捕食致死率显著更高。若二氧化碳耐受性的个体差异具备可遗传性，那么这种对高浓度二氧化碳耐受表型的选择，或可帮助缓解海洋酸化带来的影响。