Sharks are the most feared predators in the sea, and their survival hinges on fearsome teeth that regrow throughout their lives. But changes in the ocean's chemistry could put those weapons at risk. That is the takeaway from a study performed by a group of German scientists who tested the effects of a more acidic ocean on sharks' teeth. Scientists have linked human activities including the burning of fossil fuels to the ongoing acidification of the ocean, reports the AP, and as oceans become increasingly acidic, sharks' teeth could become structurally weaker and more likely to break. That could change the big fishes' status at the top of the ocean's food chain, the scientists found.
The ocean will not become populated with toothless sharks overnight, said the study's lead author, Maximilian Baum, a marine biologist at Heinrich Heine University Düsseldorf. But the possibility of weaker teeth is a new hazard to sharks that already face pollution, overfishing, climate change, and other threats, Baum said. "We found there is a corrosion effect on sharks' teeth," Baum said. "Their whole ecological success in the ocean as the rulers of other populations could be in danger." The researchers, who published their work in the journal Frontiers in Marine Science, performed their study as ocean acidification has become an increasing focus of conservation scientists.
The ocean is expected to become almost 10 times more acidic than it currently is by the year 2300, the German scientists wrote. The scientists performed their study by collecting more than 600 discarded teeth from an aquarium that houses blacktip reef sharks. They then exposed the teeth to water with the acidity of today and the projected acidity of 2300. The teeth exposed to the more acidic water became much more damaged, with cracks and holes, root corrosion, and degradation to the structure of the tooth itself. The results "show that ocean acidification will have significant effects on the morphological properties of teeth," the scientists wrote.
Shark teeth are "highly developed weapons built for cutting flesh, not resisting ocean acid," Baum said. Sharks go through thousands of teeth in a lifetime. Thankfully, sharks have a number of factors that can help them stave off the negative effects of ocean acidification, said Nick Whitney, senior scientist at the New England Aquarium. Whitney said because shark teeth develop inside the mouth tissue of sharks, they will be shielded from changes in ocean chemistry for a time. And history has taught us that sharks are survivors. "They've been around for 400 million years and have evolved and adapted to all kinds of changing conditions," he said.
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