Sharks' hunting ability destroyed under climate change

http://www.eurekalert.org/pub_releases/2015-11/uoa-sha111115.php

Public Release: 12-Nov-2015
Sharks' hunting ability destroyed under climate change
University of Adelaide

The hunting ability and growth of sharks will be dramatically impacted by increased CO2 levels and warmer oceans expected by the end of the century, a University of Adelaide study has found.

Published today in the journal Scientific Reports, marine ecologists from the University of Adelaide's Environment Institute report long-term experiments that show warmer waters and ocean acidification will have major detrimental effects on sharks' ability to meet their energy demands, with the effects likely to cascade through entire ecosystems.

The laboratory experiments, studying Port Jackson sharks and including large tanks with natural habitat and prey, found embryonic development was faster under elevated temperatures. But the combination of warmer water and high CO2 increased the sharks' energy requirement, reduced metabolic efficiency and removed their ability to locate food through olfaction (smelling). These effects led to marked reductions in growth rates of sharks.

"In warmer water, sharks are hungrier but with increased CO2 they won't be able to find their food," says study leader Associate Professor Ivan Nagelkerken, Australian Research Council (ARC) Future Fellow.

"With a reduced ability to hunt, sharks will no longer be able to exert the same top-down control over the marine food webs, which is essential for maintaining healthy ocean ecosystems."

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