Southern Seas Ecology Laboratories, School of Biological Sciences and The Environment Institute, The University of Adelaide, Adelaide, South Australia, Australia.
PLoS Biol. 2021 Jan 19;19(1):e3001033. doi: 10.1371/journal.pbio.3001033. eCollection 2021 Jan.
Ocean acidification affects species populations and biodiversity through direct negative effects on physiology and behaviour. The indirect effects of elevated CO2 are less well known and can sometimes be counterintuitive. Reproduction lies at the crux of species population replenishment, but we do not know how ocean acidification affects reproduction in the wild. Here, we use natural CO2 vents at a temperate rocky reef and show that even though ocean acidification acts as a direct stressor, it can indirectly increase energy budgets of fish to stimulate reproduction at no cost to physiological homeostasis. Female fish maintained energy levels by compensation: They reduced activity (foraging and aggression) to increase reproduction. In male fish, increased reproductive investment was linked to increased energy intake as mediated by intensified foraging on more abundant prey. Greater biomass of prey at the vents was linked to greater biomass of algae, as mediated by a fertilisation effect of elevated CO2 on primary production. Additionally, the abundance and aggression of paternal carers were elevated at the CO2 vents, which may further boost reproductive success. These positive indirect effects of elevated CO2 were only observed for the species of fish that was generalistic and competitively dominant, but not for 3 species of subordinate and more specialised fishes. Hence, species that capitalise on future resource enrichment can accelerate their reproduction and increase their populations, thereby altering species communities in a future ocean.
海洋酸化通过对生理和行为的直接负面影响影响物种种群和生物多样性。升高的 CO2 的间接影响不太为人所知，有时甚至可能违反直觉。繁殖是物种种群补充的关键，但我们不知道海洋酸化如何影响野外的繁殖。在这里，我们利用温带多岩石珊瑚礁的天然 CO2 喷口表明，尽管海洋酸化是一种直接压力源，但它可以间接增加鱼类的能量预算，在不影响生理平衡的情况下刺激繁殖。雌性鱼类通过补偿维持能量水平：它们减少活动（觅食和攻击）以增加繁殖。在雄性鱼类中，生殖投资的增加与更多食物摄入有关，这是由升高的 CO2 对初级生产力的受精作用介导的。此外，喷口处猎物的生物量更大，藻类的生物量也更大，这是由升高的 CO2 对初级生产力的施肥作用介导的。此外，CO2 喷口处的雄性养育者的数量和攻击性也有所增加，这可能进一步提高繁殖成功率。这些升高的 CO2 的积极间接影响仅在那些普遍存在且具有竞争优势的鱼类物种中观察到，而在 3 种处于从属地位且更专业化的鱼类中则没有观察到。因此，能够利用未来资源丰富的物种可以加速其繁殖并增加其种群，从而改变未来海洋中的物种群落。
