Rising acidity in Earth's oceans could be weakening sharks' teeth, potentially inhibiting their ability to capture prey, according to a new study.

What's happening?

A study published in Frontiers in Marine Science set out to research the impact of ocean acidity on shark teeth. Unlike human teeth, shark teeth aren't protected by gums, making them more susceptible to water changes. 

"Since ocean acidification is known to damage calcified structures like corals and shells, we wanted to investigate whether shark teeth … might also be vulnerable," said Maximilian Baum, lead author of the study and biologist at Heinrich Heine University in Düsseldorf, Germany, per CNN.

Researchers studied changes in the teeth of the blacktip reef shark under more acidic ocean levels. While normal ocean pH is around 8.1, projections indicate it could decrease to as low as 7.3 by 2300. After eight weeks at 7.3, researchers observed visible tooth degradation, including cracks, holes, and corroded roots.

"Shark teeth are highly specialized weapons built for cutting flesh, not resisting ocean acid," Baum said, per The Times of India.

Why is this study important?

Over the past century, oceans have absorbed 90% of the excess heat on the planet. As oceans warm, acidity also increases. Since the onset of the Industrial Revolution, ocean acidification has risen by about 30%, according to NASA.

Past studies have shown how acidic waters impact smaller marine life, such as corals, which show structural weakness in rising acidic waters. This new study shows this effect on the other end of the food chain.

"Our main takeaway is that not only small organisms like corals or mollusks are at risk: Even the teeth of apex predators show visible damage under acidified conditions," Baum said, per CNN.

As apex predators, sharks are vital to ocean ecosystems. According to the National Oceanic and Atmospheric Administration, sharks help maintain healthy fish populations, allowing ocean habitats, including coral reefs and seagrass, to thrive. They also help keep carbon stores in the ocean rather than in the atmosphere. However, shark and ray populations have declined by 71% over the last 50 years, and the International Union for Conservation of Nature classified 17% of more than 1,000 species assessed as threatened. 

According to CNN, Baum worries that if sharks lose their resilience and issues such as overfishing and plastic pollution grow, it could trigger a devastating domino effect across ocean ecosystems. 

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"The survival of their kind is vital not just for sharks but for the entire ecosystem in the seas around the world," Baum said, per The Times of India.  

What's being done about ocean acidity levels?

As the researchers themselves admit, this study has limitations, and further studies will help gather more information. 

"It will be interesting to see in future studies if the damage to teeth seen in studies like this one results in a functional effect on a tooth's ability to do its job," said Lisa Whitenack, a professor at Allegheny College who was not involved in the study, according to The Guardian.

Surprisingly, some marine life, including coral, has shown resiliency to rising ocean acidity and maintained biological functions. While more studies can provide further insight into the impact on sharks, individuals can also take steps to slow the rise in ocean acidity. One way is to reduce reliance on coal, oil, and gas. Restoring coastal ecosystems can also help maintain marine populations and reduce acidity.

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