Sharks rely on their razor-sharp teeth – replaced every few days to ensure maximum killing power – to survive. But this weapon is under threat, which could spell disaster for one of the ocean’s top predators.
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The more carbon dioxide humans release into the atmosphere, the more the ocean absorbs. With increased absorption of carbon dioxide, the ocean becomes more acidic, and by 2300 the sea is projected to be ten times more acidic than it currently is. This is likely to be catastrophic for animals such as corals and shellfish, but how this acidification might affect top predators isn’t well understood.
A new study, published in Frontiers in Marine Science, explores the impact ocean acidification will have on sharks by focussing in on one of their most important survival tools: their teeth.
The researchers collected newly shed teeth from captive blacktip reef sharks. Blacktip reef sharks must swim with their mouths open – and their teeth exposed – in order to breathe, and their teeth are therefore extremely vulnerable to the effects of ocean acidification. By placing the collected teeth in acidified seawater, the scientists could observe what might happen to shark teeth in the near future.
The results are not good news for sharks. In more acidic seawater, shark teeth begin to crumble. They develop cracks and holes, and the roots corrode. But what does this mean for the ocean’s top predators?
“Damaged teeth may reduce feeding efficiency,” Maximilian Baum, lead author of the study, tells BBC Wildlife. “Over time, this could affect their hunting success, fitness and ecological role.”
There is a possibility that sharks might be able to repair their teeth by remineralising them. While costly, this would increase the sharks’ chances of surviving ocean acidification.
Unfortunately, it is not only acidification that sharks have to contend with.
“Acidification adds to many other human-driven stressors like overfishing, pollution and habitat loss,” Maximilian says. “The speed and scale of change may outpace their ability to adapt.”
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Top image: a great white shark. Credit: Getty
