Sharks’ Teeth Could Suffer Damage as Ocean Acidification Intensifies, Study Suggests

Higher concentrations of carbon dioxide in the atmosphere are leading to a drop in ocean pH, a change that might eventually make it harder for sharks to eat their prey

Sara Hashemi | Daily Correspondent

August 28, 2025

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As carbon emissions increase and the world warms, oceans are becoming more acidic, in a process that’s weakening corals and making it harder for oysters to build shells. Now, a new study suggests these changing waters could also lead shark teeth to decay.

Oceans are a key carbon sink, naturally absorbing carbon dioxide from the atmosphere. But now, human-made carbon dioxide emissions are increasing the amount of the gas getting absorbed, reacting with seawater and leading to acidification. Any pH levels below seven are acidic, while anything above seven is basic (or alkaline). Studies have shown that ocean pH has dropped by around 30 percent since pre-industrial times, and one projection suggests that pH levels could go from about 8.1 currently to 7.3 by 2300.

To understand how acidification impacts sharks, a team of researchers tested 16 undamaged shark teeth and 36 teeth with limited damage—and within each group of teeth, half went into a tank with pH levels close to those of the current day (8.19), and half went into a tank with a pH that matched future projections (7.3). The teeth had all been discarded by blacktip reef sharks housed in an aquarium, then collected by divers.

After eight weeks, the teeth in the more acidic water had suffered significantly more damage. “We observed visible surface damage such as cracks and holes, increased root corrosion and structural degradation,” says study senior author Sebastian Fraune, a biologist at Heinrich Heine University Düsseldorf in Germany, in a statement. The findings were published in the journal Frontiers in Marine Science on August 26.

“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, suggesting that ocean acidification could impact sharks more directly than previously assumed,” says lead author Maximilian Baum, another biologist at Heinrich Heine University Düsseldorf, in an email to Katie Hunt at CNN.

This damage could impact sharks’ ability to eat their prey. Phil Hollyman, an ecologist at Bangor University in Wales who was not involved in the work, tells Adam Vaughan at the London Times that weaker teeth could make sharks less competitive when hunting for food.

The work does have a few limitations. The study authors note that the repair process for teeth may be different in living species compared to in teeth that have fallen out. Living sharks could potentially remineralize or replace their damaged teeth more quickly, explains Fraune in a statement, but the process may use up more energy in acidified oceans.

Additionally, sharks continually replace their teeth, sometimes as often as every two weeks. Lisa Whitenack, a shark tooth expert at Allegheny College not involved in the work, suggests that this tooth replacement could potentially keep up with any damage the animal’s teeth might face. “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 … [and if] damaged teeth can still cut or puncture prey,” she says to Sophie Kevany at the Guardian.

Still, the study highlights the importance of looking at how ocean acidification might impact wildlife in unexpected ways, especially since sharks are key apex predators, says Baum to CNN.

“If sharks and their resilience were to be weakened by ocean acidification in combination with other stressors such as overfishing and plastic pollution, this could trigger cascading and domino effects across many marine ecosystems,” he adds.

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.