Aquatic species shrink with warming

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LONDON, Nov. 5 (UPI) -- Warming temperatures cause greater reduction in the adult sizes of aquatic animal species than in land-dwellers, British researchers say.

Scientists at Queen Mary, University of London and the University of Liverpool said body size of both marine and freshwater species is more significantly affected by warmer temperatures, with possible impacts on aquatic food webs and the production of food by aquaculture.

"Given that fish and other aquatic organisms provide 3 billion people with at least 15 percent of their animal protein intake, our work highlights the importance of understanding how warming in the future will affect ocean, lake and river dwelling species," Jack Forster of Queen Mary's School of Biological and Chemical Sciences said.

The most likely cause of the difference in size change is due to the much lower availability of oxygen in water than in air, the researchers said.

"To satisfy increased demands for oxygen at higher temperatures, aquatic species have fewer options," Liverpool's David Atkinson said. "Reducing the size at which they mature is their way of balancing oxygen supply and demand."

The difference between how aquatic and land species react to warmer temperatures is dramatic, the researchers said.

"Aquatic animals shrink 10 times more than land-dwellers in species the size of large insects or small fish," Queen Mary researcher Andrew Hirst said. "While animals in water decrease in size by 5 percent for every degree Celsius of warming, similarly sized species on land shrink, on average, by just half a percent."

The study was published in Proceedings of the National Academy of Sciences.