The rising acidity of Earth’s oceans is causing shark teeth to corrode and waste away.
As top predators, a shark’s teeth are its most important tool, but a new study has found that climate change is damaging and weakening them.
“They’re highly developed weapons built for cutting flesh, not resisting ocean acid,” said the study’s lead, Maximilian Baum from Heinrich Heine University of Düsseldorf (HHU). “Our results show just how vulnerable even nature’s sharpest weapons can be.”
Though sharks constantly replace their teeth, the worsening condition of our oceans could soon damage them faster than they can be repaired.
As our oceans soak up more and more carbon dioxide due to climate change, they’re becoming increasingly acidic.
Currently, the oceans are slightly alkaline with a pH of 8.1, but this could drop to as low as 7.3 by 2300.
As part of an undergraduate project, which has now been published in Frontiers, Baum aimed to find out how much of an impact this change could have on marine life.
As the animals regularly shed their teeth, he was able to acquire hundreds of blacktip reef shark teeth from aquariums housing the animals to use in the investigation.
Around 50 of the intact and undamaged teeth were then placed into tanks filled with water at various pHs, and kept there for eight weeks.
When they were inspected at the end of the experiment, it was clear that the teeth in the acidic water had considerably more damage than the 8.1 pH water.
“We observed visible surface damage such as cracks and holes, increased root corrosion, and structural degradation,” said Prof Sebastian Fraune from HHU, who supervised the project.
The acidic water also caused the surface of the teeth to become rough and irregular. While this might have helped aid in the shark’s cutting ability, it also compromised the tooth’s structure. This weakened them and made them more prone to breaking.
“Maintaining ocean pH near the current average of 8.1 could be critical for the physical integrity of predators’ tools,” said Baum. “It’s a reminder that climate change impacts cascade through entire food webs and ecosystems.”
About our expert
Maximilian Baum is a student at the Department of Biology at Heinrich Heine University of Düsseldorf.
Prof Sebastian Fraune is the head of the Zoology and Organismic Interactions Institute at Heinrich Heine University of Düsseldorf.
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