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World - As the ocean heats up hungrier predators take control

A hotter ocean is a hungrier ocean -- at least as far as fish predators are concerned. Scientists have discovered predator impacts in the Atlantic and Pacific peak at higher temperatures. The effects cascade down to transform other life in the ocean, potentially disrupting balances that have existed for millennia.

A hotter ocean is a hungrier ocean -- at least as far as fish predators are concerned. In a new field study published online June 9 in Science, Smithsonian scientists discovered predator impacts in the Atlantic and Pacific peak at higher temperatures. The effects cascade down to transform other life in the ocean, potentially disrupting balances that have existed for millennia.

"It's taken thousands of years to get to this state, and then suddenly we're ramping up the temperature at a much higher rate," said Gail Ashton, lead author of the report and marine biologist with the Smithsonian Environmental Research Center (SERC). "And we don't really know the implications of that temperature increase."

Past research has hinted that predators are more active in the tropics, since higher temperatures tend to increase animals' metabolism. But empirical evidence from smaller studies was conflicting. And few studies tried to nail down the central question of how prey communities respond to the increased pressure, which could foreshadow what a warmer ocean of the future will look like.

"Warmer waters tend to favor animals high in the food chain, which become more active and need more food -- and it's their prey who pay for that increased activity," said co-author Emmett Duffy, director of the Smithsonian's Marine Global Earth Observatory network (MarineGEO). "This suggests that warming seas could see big shifts in the life of sensitive seabed habitats."

Tracking Predation From Pole to Pole

The new study took one of the largest views to date. An international team led by the Smithsonian and Temple University coordinated partners at 36 sites, running along the Atlantic and Pacific coasts of the Americas. The sites spanned from Alaska in the north to Tierra de Fuego at the tip of South America. At each site, researchers performed the same three experiments on predators and prey.

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