Saltwater crocodiles spend less time underwater when temperatures increase, putting their survival at risk as the climate change heats up water sources.
Crocodiles dive underwater to find food, avoid predators, socialise and sleep. They can dive underwater as many as 70 times per day.
Further, air temperatures in the high 30s and low 40s can be lethal for crocs, requiring them to find cold water to cool down and avoid dehydration.
The researchers at the University of Queensland exposed the crocs to three different warming scenarios – water temperators of 28°C, 31.5°C and 35°C. 28°C is the current norm in summer.
The tests were conducted in a large tank, divided into three for the different temperatures. The crocs were coaxed underwater by researchers making loud noises.
As temperatures increased, the amount of time crocs spent under water decreased.
“Acute increases in water temperature resulted in significantly shorter crocodile dives,” said PhD student, Essie Rodgers, the lead author of the study.
“Their submergence times halved with every 3.5°C increase in water temperature.”
“We thought that crocodiles – like many animals – would adjust to temperature changes so life continues,” says Professor Craig Franklin from the University of Queensland.
“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.”
Further research needs to be undertaken before the full consequence of increased temperatures are known.
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