Marine ecologists say that the climbing human CO2 emissions result in collapsing of food chain

The expected ocean acidification and warming may lead to a reduction in diversity and numbers of various key species that underpin marine ecosystems around the world, according to the paper published in the journal Proceedings of the National Academy of Sciences (PNAS) recently.
"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.
The researcher 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 Associate Professor Nagelkerken and fellow University of Adelaide marine ecologist Professor Sean 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."
They found that there would be "limited scope" for acclimation to warmer waters and acidification. Little species can avoid the negative effects of increasing CO2 except microorganisms, which are expected to increase in number and diversity.
Seeing from the total food web, primary production from the smallest plankton is expected to increase in the warmer waters but this often doesn't translate into secondary production. It means decreased productivity under ocean acidification.
According to Associate Professor Nagelkerken, with higher metabolic rates in the warmer water which results in a greater demand for food, there is a mismatch with less food available for carnivores, which are bigger fish that fisheries industries are based around. They think there will be species collapse from the top of the food chain down.
Besides, acidification would decrease the dimethylsulfide gas production by ocean plankton which helps cloud formation and therefore in controlling the Earth's heat exchange.
From the global analysis we can see that human CO2 emissions are badly affecting global fisheries and ocean ecosystems. That's a terrible picture that we don't want to see. Shouldn't we do something positive next?
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