As oceans become more acidic, sharks’ teeth may become structurally weaker and more prone to break
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Famously, sharks are able to replace their teeth. New ones always grow as they use their current set. Yet the ability for these mighty predators to grow teeth might not be enough to withstand the pressures of a warming world.
As oceans become more acidic, researchers in Germany have found shark teeth take a serious blow, with acidic oceans leading to more brittle and weak teeth.
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‘Shark teeth, despite being composed of highly mineralised phosphates, are still vulnerable to corrosion under future ocean acidification scenarios,’ said first author of the Frontiers in Marine Science article, Maximilian Baum
‘They are high developed weapons built for cutting flesh, not resisting ocean acid. Our results show just how vulnerable even nature’s sharpest weapons can be.’
Ocean acidification is a process by which the ocean’s pH values keep decreasing, a phenomenon mostly drivn by the release of human-generated CO2. Currently, the average pH of the world’s oceans is 8.1, but by 2300, it is expected to drop to 7.3 – making it almost ten times more acidic than it currently is.
For the study, researchers used these two pH values to examine the effects of more and less acidic water on the teeth of Blacktip reef sharks. Divers collected more than 600 discarded teeth from an aquarium housing the sharks, with 16 teeth used for the pH experiment and another 36 used to measure the before and after circumference. Following this collection, teeth were then incubated for eight weeks in separate 20-litre tanks.
Compared to teeth incubated at 8.1 pH, the teeth exposed to more acidic water were significantly more damaged. Scientists observed holes, cracks, increased root erosion and structural damage. As well as this, tooth surfaces became much more irregular, potentially making them structurally weaker and more prone to brake.
Blacktip reef sharks must swim with their mouths permanently open to be ale to breathe, so their teeth are constantly exposed to water. If water is too acidic, the teeth automatically take the damage.
‘Even moderate drops in pH could affect more sensitive species with slow tooth replication circles or have cumulative impacts over time,” Baum explained. ‘Maintaining ocean pH near the current average of 8.1 could be critical for the physical integrity of predators’ tools.’
Researchers say that future research could look at changes in teeth and their chemical structure in live sharks.
