Warmer ocean temperatures affecting baby sharks

Researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE), administered by James Cook University (JCU) and working with the University of Massachusetts have found that as climate change causes the world’s oceans to warm, baby sharks are born smaller, exhausted, undernourished and into environments that are already difficult for them to survive in.

PhD candidate, Carolyn Wheeler, examined the effects of increased temperatures (up to 31°C) on the growth, development and physiological performance of epaulette sharks – an egg-laying species found only on the Great Barrier Reef (GBR).

‘The hotter the conditions, the faster everything happened, which could be a problem for the sharks. The embryos grew faster and rapidly depleted their yolk sac, which is their only source of food whilst developing in the egg.’

Embryos hatched earlier than usual, were smaller, and hatchlings needed to feed almost straight away – while lacking significant energy.

Associate Professor Jodie Rummer, a Discovery Early Career Researcher Award recipient from Coral CoE at JCU, says the waters of the GBRwill likely experience summer averages close to or even exceeding 31°C by the end of the century.

‘The epaulette shark is known for its resilience to change, even to ocean acidification,’ Dr Rummer says. ‘So, if this species can’t cope with warming waters then how will other, less tolerant species fare?’

The research was a collaborative effort between the Anderson Cabot Center for Ocean Life and the husbandry staff at the New England Aquarium in Boston.

	‘THE STUDY PRESENTS A WORRYING FUTURE GIVEN THAT SHARKS ARE ALREADY THREATENED SHARKS ARE IMPORTANT PREDATORS THAT KEEP OCEAN ECOSYSTEMS HEALTHY. WITHOUT PREDATORS, WHOLE ECOSYSTEMS CAN COLLAPSE WHICH IS WHY WE NEED TO KEEP STUDYING AND PROTECTING THESE CREATURES,’ SAYS PHD CANDIDATE, CAROLYN WHEELER.