CO2 impact on calcification in marine bivalves - a key to understand past, present and future climate records of polar ecosystems

二氧化碳对海洋双壳类钙化的影响——了解极地生态系统过去、现在和未来气候记录的关键

• 批准号: 75405102
• 负责人: Professor Dr. Hans-Otto Pörtner
• 金额: --
• 依托单位: Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/75405102?language=en
• 关键词: CO2; impact; calcification; marine; bivalves

Future ocean acidification and global warming caused by anthropogenic CO2 have the potential to adversely affect many marine organisms. Understanding what effects the rapid increase in atmospheric CO2 levels as well as associated trends of temperature rise, have on the physiological performance and calcification processes of marine organisms is an important emerging research topic. The German BMBF (“Bundesministerium für Bildung und Forschung”) has recently funded the national BIOACID research program, where many scientists from different fields and with different background look at the consequences of increasing CO2 levels in the ocean, other international programs dealing with the same query are EPOCA (“European project of ocean acidification”) and a not jet running but already accepted national project on ocean acidification in Britain. The present study will contribute to this more and more developing research field. Since CO2 rapidly equilibrates with the surface ocean, increased CO2 levels in the atmosphere will cause an increase in seawater partial pressure of CO2 (PCO2) with a concomitant decrease in seawater pH (IPCC 2007). An estimated reduction in seawater pH to 7.3 by approximately 0.7 pH units is expected within the next 300 years. Even smaller reductions in seawater pH at elevated PCO2 have an impact on physiological processes in marine organisms, in particular on those related to carbonate skeleton formation. Lower pH values decrease the availability of carbonate (CO2 −3) ions and lower the saturation state of the major shell forming carbonate minerals. The colder the water, the more CO2 is absorbed: consequently, Polar Regions will be the areas where surface seawaters will most likely become undersaturated with respect to aragonite, a form of carbonate ion cluster used by Serripes groenlandicus to build their shell. The energy budget of shell formation may be particularly sensitive to ocean acidification, as may be the quality of the shell. Present hypotheses see a key role of the capacity to regulate extracellular acid-base status in defining the sensitivity of marine ectothermic animals to elevated CO2 tensions. First results show, that Serripes groenlandicus is not able to maintain extracellular pH under elevated CO2 tensions as expected according to future scenarios. During longterm incubations (nine weeks) extracellular pH continues to be completely uncompensated. Most likely this arctic mussel is more susceptible to elevated CO2 than other marine animals like fish or crustaceans, due to their inability to maintain extracellular acid-base status.

未来由人为二氧化碳引起的海洋酸化和全球变暖有可能对许多海洋生物产生不利影响。了解大气CO2水平的快速增加以及与之相关的温度上升趋势对海洋生物生理性能和钙化过程的影响是一个重要的新兴研究课题。德国BMBF最近资助了国家生物酸化研究计划，许多来自不同领域和不同背景的科学家都在研究海洋中二氧化碳水平上升的后果，其他处理同样问题的国际计划有EPOCA（“欧洲海洋酸化项目”）和英国一个虽然没有喷气机运行但已经接受的国家海洋酸化项目。本文的研究将为这一日益发展的研究领域做出贡献。由于二氧化碳与海洋表面迅速平衡，大气中二氧化碳水平的增加将导致海水二氧化碳分压（PCO2）的增加，同时海水pH值降低（IPCC 2007）。预计在未来300年内，海水pH值将降低约0.7个pH单位，降至7.3。在二氧化碳分压升高的情况下，即使海水pH值的小幅下降也会影响海洋生物的生理过程，特别是与碳酸盐骨架形成有关的生理过程。较低的pH值降低了碳酸盐（CO2−3）离子的可用性，降低了主要形成壳的碳酸盐矿物的饱和状态。水越冷，吸收的二氧化碳越多：因此，极地地区将是表层海水最有可能因文石而变得不饱和的地区，文石是一种碳酸盐离子簇的形式，被绿鳍海鲈用来建造它们的外壳。贝壳形成的能量收支可能对海洋酸化特别敏感，贝壳的质量也可能如此。目前的假设认为，调节细胞外酸碱状态的能力在确定海洋恒温动物对二氧化碳浓度升高的敏感性方面发挥了关键作用。第一个结果表明，根据未来的设想，在二氧化碳浓度升高的情况下，绿刺草不能维持细胞外pH值。在长期孵育（9周）期间，细胞外pH值继续完全不受补偿。这种北极贻贝很可能比鱼类或甲壳类动物等其他海洋动物更容易受到二氧化碳升高的影响，因为它们无法维持细胞外酸碱状态。