中国科技网10月13日报道（张微 编译）世界首个全球性的分析报告，关于海洋对人类不断攀升的二氧化碳排放的反应，为我们描绘了未来渔业和海洋生态系统的严峻场景。

发表在今天出版的美国国家科学院院刊(PNAS)上，阿德莱德大学的海洋生态学家的报告说，预期的海洋酸化和气候变暖可能导致世界范围内支撑海洋生态系统的多样性以及各种关键物种数量的下降。

“这个‘简化版’的海洋将对我们目前的生活方式，特别是对沿海居民和那些依靠海洋生活的人们产生深远的影响，” 阿德莱德大学环境研究所，澳大利亚研究理事会Future Fellow，副教授Ivan Nagelkerken说。

Ivan Nagelkerken副教授和阿德莱德大学海洋生态教授西恩 康奈尔对已经发布的632项实验数据进行了荟萃分析，这些实验覆盖了热带到北极水域，以及各种珊瑚礁的一系列生态系统，从海洋中的海藻林到开放的海洋。

“我们对于气候变化将如何影响海洋环境知之甚少，”康奈尔教授说。“到现在为止，几乎完全依赖于对潜在的全球变化的定性评论与观点。这个研究领域也存在一些定量评估，但它们通常集中研究单一的压力因素，单一的生态系统或对单一物种所带来的影响。”

“我们的分析集中了所有这些实验的结果，来研究多个压力因素对整个海洋的综合影响，包括物种间的相互作用，以及应对气候变化的不同措施。”

研究人员发现，除了‘有限范围’的海域对水温变暖和海水酸化能够适应。几乎没有物种能够逃离不断增加的二氧化碳排放的负面影响，必将伴随全球范围内物种多样性和种群丰度的大幅减少。有一个例外就是微生物，它们的数量和多样性将会增加。

从一个全食物网的角度看，在温暖的海水条件下，最小的浮游生物的初级生产量(生态食物链中的第一环)将会增加，但这并不代表次级生产量(浮游动物和小鱼)也会水涨船高，这表明在海洋酸化情况下，生产量在降低。

“温暖海水伴随着高代谢率，因此对食物的需求量更大，这就造成食肉动物(渔业产业重要的来源，较大的鱼类)的食物短缺，” Ivan Nagelkerken副教授说。“这就是食物链顶端物种的食物链崩溃。”

分析还表明，随着海水升温或海洋酸化加剧或二者兼有，就会对物种栖息地的形成造成有害影响，例如珊瑚，牡蛎和贻贝。栖息地生态的任何微小的变化，都会对各种各样的珊瑚礁物种带来广泛的影响。

这项研究的另一个发现是，海洋酸化将导致甲基气体(DMS)的下降，这个气体是海洋浮游生物产生的，将有助于云的形成，并由此控制地球的热交换。

英文原文：

Global marine analysis suggests food chain collapse

A world-first global analysis of marine responses to climbing human CO2 emissions has painted a grim picture of future fisheries and ocean ecosystems.

Published today in the journal Proceedings of the National Academy of Sciences (PNAS), marine ecologists from the University of Adelaide say the expected ocean acidification and warming is likely to produce a reduction in diversity and numbers of various key species that underpin marine ecosystems around the world.

"This 'simplification' of our oceans will have profound consequences for our current way of life, particularly for coastal populations and those that rely on oceans for food and trade," says Associate Professor Ivan Nagelkerken, Australian Research Council (ARC) Future Fellow with the University's Environment Institute.

Associate Professor Nagelkerken and fellow University of Adelaide marine ecologist Professor Sean Connell have conducted a 'meta-analysis' of the data from 632 published experiments covering tropical to artic waters, and a range of ecosystems from coral reefs, through kelp forests to open oceans.

"We know relatively little about how climate change will affect the marine environment," says Professor Connell. "Until now, there has been almost total reliance on qualitative reviews and perspectives of potential global change. Where quantitative assessments exist, they typically focus on single stressors, single ecosystems or single species.

"This analysis combines the results of all these experiments to study the combined effects of multiple stressors on whole communities, including species interactions and different measures of responses to climate change."

The researchers found that there would be "limited scope" for acclimation to warmer waters and acidification. Very few species will escape the negative effects of increasing CO2, with an expected large reduction in species diversity and abundance across the globe. One exception will be microorganisms, which are expected to increase in number and diversity.

From a total food web point of view, primary production from the smallest plankton is expected to increase in the warmer waters but this often doesn't translate into secondary production (the zooplankton and smaller fish) which shows decreased productivity under ocean acidification.

"With higher metabolic rates in the warmer water, and therefore a greater demand for food, there is a mismatch with less food available for carnivores—the bigger fish that fisheries industries are based around," says Associate Professor Nagelkerken. "There will be a species collapse from the top of the food chain down."

The analysis also showed that with warmer waters or increased acidification or both, there would be deleterious impacts on habitat-forming species for example coral, oysters and mussels. Any slight change in the health of habitats would have a broad impact on a wide range of species these reefs harbour.

Another finding was that acidification would lead to a decline in dimethylsulfide gas (DMS) production by ocean plankton which helps cloud formation and therefore in controlling the Earth's heat exchange.

来源：中国科技网—科技日报