Climate change to collapse ocean’s food chain

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Fish Extinction Due to Ocean Problems

Ocean Cycle

University of Adelaide ecologists say that expected ocean acidification and climate change is raising the risk of producing a reduction in diversity and numbers of different species –

Adelaide, Australia – The University of Adelaide team of marine ecologists say that 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.

Associate Professor Nagelkerken and fellowUniversity 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.”

According to Associate Professor Ivan Nagelkerken, Future Fellow with the University’s Environment Institute, Australian Research Council (ARC), “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.”

Researchers discovered that there would be “limited scope” for acclimation to warmer waters and acidification. Limited species will survive negative effects of rising CO2, with an expected large reduction in species diversity and abundance globally. Microorganisms will be an exception, they are expected to increase in number and diversity.

From the food chain 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.”

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. The study was published today in the journal Proceedings of the National Academy of Sciences (PNAS).

Source: EurekAlert. Compiled for Dr. David Jensen by Larry Heinrichs

 

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