Hot water puts crocs at risk

http://www.eurekalert.org/pub_releases/2015-12/uoq-hwp120815.php

Public Release: 15-Dec-2015
Hot water puts crocs at risk
University of Queensland

Australia's saltwater crocodiles appear to be in hot water, with a University of Queensland study linking climate warming to shorter dives, putting the crocs' survival at risk.

Professor Craig Franklin of the UQ School of Biological Sciences said saltwater crocodiles exposed to long-term elevated water temperature spent less time submerged once water temperature exceeded 31.5 degrees Celsius.

"We thought that crocodiles - like many animals - would adjust to temperature changes so life continues," he said.

"However, we were surprised to find they had little capacity to compensate for water temperature changes and seemed to be hard-wired to operate at certain temperatures.

"We are not sure what this means, but it's likely that if the water is too hot, crocodiles might move to cooler regions, or will seek refuge in deep, cool water pockets to defend their dive times."

Lead author and PhD student, Essie Rodgers, said crocodiles spend up to 11 hours a day submerged. Their diving capacity is important to avoid predators, to forage, for sleep/recovery and for social interactions, which all occur underwater.

"Crocodiles are ectothermic animals - where environmental temperatures strongly influence their body temperatures," she said.

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