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Food chain collapse predicted in world's oceans

AFP logoAFP 10/14/2015
A wave breaks above a coral escarpement in an area called the 'Coral Gardens' located at Lady Elliot Island and 80 kilometers north-east from the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkeled on Australia's Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". Picture taken June 10, 2015. © REUTERS/David Gray A wave breaks above a coral escarpement in an area called the 'Coral Gardens' located at Lady Elliot Island and 80 kilometers north-east from the town of Bundaberg in Queensland, Australia, June 10, 2015. UNESCO World Heritage delegates recently snorkeled on Australia's Great Barrier Reef, thousands of coral reefs, which stretch over 2,000 km off the northeast coast. Surrounded by manta rays, dolphins and reef sharks, their mission was to check the health of the world's largest living ecosystem, which brings in billions of dollars a year in tourism. Some coral has been badly damaged and animal species, including dugong and large green turtles, are threatened. UNESCO will say on Wednesday whether it will place the reef on a list of endangered World Heritage sites, a move the Australian government wants to avoid at all costs, having lobbied hard overseas. Earlier this year, UNESCO said the reef's outlook was "poor". Picture taken June 10, 2015.

The world's oceans are teeming with life, but rising carbon dioxide emissions could cause a collapse in the marine food chain from the top down, researchers in Australia said Monday.

The first-of-its-kind global analysis of marine responses to climate change forecasts a grim future for fish.

Marine ecologists from the University of Adelaide reviewed more than 600 published studies on coral reefs, kelp forests, open oceans, and tropical and arctic waters.

Their meta-analysis, published in the October 12 edition of the US peer-reviewed journal Proceedings of the National Academy of Sciences, showed that ocean acidification and warming will cut down on the diversity and numbers of various key species.

"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," said associate professor and co-author Ivan Nagelkerken.

Very few organisms are expected to be able to adjust to warmer waters and acidification, with the exception of microorganisms, which are expected to increase in number and diversity.

But the increase in the smallest plankton is not expected to translate into more zooplankton and small fish, meaning bigger fish will struggle to find enough food to eat.

"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," said Nagelkerken.

"There will be a species collapse from the top of the food chain down."

Oysters, mussels and corals are also expected to take a hit from global warming, which will further harm the environment for reef fish.

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