Study shows crocs dive less in warmer waters

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Melbourne, July 7 (ANI): A study on the diving behaviour of freshwater crocodiles (Crocodylus johnstoni) has shown that they dive less in warmer waters.

A team led by Dr Hamish Campbell, from the University of Queensland in Brisbane, said that warmer temperatures make it harder for crocodiles to spend time diving under the water, foraging, and resting.

They explained that since crocodiles are cold-blooded animals, the temperature of the environment affects their body temperature and metabolic rate.

The warmer it is, the higher their metabolism and oxygen use, which could affect how much time they spend under water.

Campbell and colleagues studied the crocodiles in a national park in Queensland to see if this was the case.

Research team member Dr Matthew Gordos, a conservation manager with the NSW government, said devices were attached to the crocodiles to measure how deep they dove and for how long.

The crocodiles were also fitted with sensors to measure the temperature of their body and of the surrounding water, and the team then compared thousands of measurements taken during summer and winter.

They found that in summer the water temperature rose by a few degrees and the crocodiles' body temperature was higher than in winter.

Gordos said the study showed the animals spent less time under water in summer and whenever the crocodiles dove for longer than 40 minutes they had to spend exponentially longer on the surface.

"In summer time they're using their oxygen up much quicker," ABC Science quoted him as saying.

He said this is likely because the animals need time to recover from anaerobic respiration necessary for longer dives in summer.

Gordos said the findings of the study suggest that crocodiles could be adversely affected if predicted warming of several degrees occurs.

"It exposes them to predators and if they are diving to forage they have less time because they have to spend more time at the surface," he said.

"It [a temperature rise] could put them outside a comfortable range and you might start seeing population declines or they might have to shift where they're distributed," he added.

The findings have been published in the Proceedings of the Royal Society B. (ANI)

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