海洋酸化和全球变暖对贝类生理生态的影响研究进展

Abstract

研究表明海洋酸化和全球变暖已严重威胁到海洋生态系统稳的定性及生物多样性。由于人类活动，大气中不断增加的CO₂不仅造成全球气候异常，而且大量的CO₂被海洋吸收，造成了海水中H⁺浓度增加，即海洋酸化（Ocean Acidification）。海洋酸化严重影响海洋生物的生存和繁衍，尤其是有壳类生物，如贝类，甲壳类，棘皮类等。主要影响方面包括生物的产卵受精，孵化，早期发育，钙化，酸碱调节，免疫功能，蛋白质合成，基因表达，摄食及能量代谢等一系列和生理相关的机能，进而对个体行为学，种群结构和海洋生态系统造成严重危害。目前，已有大量海洋酸化对海洋贝类的生理生态影响的报道，与此同时，全球变暖导致海洋温度升高伴随着海洋酸化同步发生。因此，为了更加准确地预测海洋生物应对全球气候变化的生理生态应答，越来越多的学者开始致力于研究温度和海洋酸化的复合胁迫对海洋生物交互影响作用。综述了近年来海洋酸化对贝类生理生态的影响，主要从个体早期发育、钙化、免疫、繁殖等方面做了系统的阐述，还对酸化和温度对贝类的复合环境胁迫效应也做了综合分析，以期为今后的海洋酸化研究提供基础理论。;Global climate change due to industrialization and anthropogenic activities has been a critical problem worldwide since the last century. Because of anthropogenic activity, the increasing atmospheric concentration of CO₂ not only caused temperature rise, but also increased the H⁺ concentration in the seawater with the large CO₂ absorption, namely ocean acidification. Global average sea surface temperature is significantly higher than before, and the ocean surface pH is also evidently reduced because of the sequestration of a large number of CO₂ by the ocean. Elevated atmospheric CO₂ is set to increase mean global temperatures by 2-4℃, and reduce the surface ocean pH by as much as 0.5 unit in the next century. It is crucial to forecast the impacts of global climate change on eco-physiology of marine organisms, especially in a multiple stressor situation expected by the end of this century. Some studies have showed that ocean acidification and global warming heavily threaten the marine ecosystem and biodiversity. Ocean acidification affects survival and reproduction of marine organisms negatively, especially those organisms with shells, such as shellfish, crustacean and echinodermata. The most influenced aspects include fertilization, hatching, early development, calcification, acid-base balance, immune function, protein synthesis, gene expression, feeding and energy metabolism, all of which are relevant to physiological functions, and ocean acidification further impacts the individual behavior, population structure and marine ecosystem. To date, a large number of studies have revealed eco-physiological responses of shellfish to ocean acidification, focusing on the mechanisms that underlie physiological plasticity at molecular level with some reference to whole organism fitness. At the same time, seawater temperature rise resulting from global warming occurs with ocean acidification simultaneously. However, the combined effects of elevated temperature and pH variation on coastal and estuarine shellfish are less explored. Many sessile organisms, such as mussels, are unable to move fleetly to avoid warming and acidified areas, so their physiological activities and behavioural responses may be influenced. There is a growing demand to understand the responses of the marine biota to these environmental stressors. Thus, to predict the eco-physiological responses of marine organisms to global climate change more realistic and accurate, more and more researchers try to study the combined effects of warming and ocean acidification. This paper reviewed eco-physiological effects of ocean acidification on shellfish in recent years, mainly from individual early development, calcification, immune responses and reproduction etc. Moreover, the combined effects of ocean acidification and warming on shellfish were summarized and analyzed, expecting to provide some basic information for studying biological responses to ocean acidification in the future. The future worthy research points include the latitudinal variation in the eco-physiological responses of species populations, the latent effects or carry-over effects, referring to effects resulting from conditions experienced in adult or larval stage, that are expressed in subsequent stages, and the interactions between shellfish and their predators. Such information is needed if we are to determine if future climate change will drive a reorganization of benthic communities and also adversely impact commercially important fisheries. Scientific progress generated by such eco-physiological studies will be central to meeting current and future conservation and management goals.