Recent studies paint a terrifying picture of ocean acidification’s effect on shark teeth. These oceanic top dogs could be losing their killer chomp. Ocean acidification is the result of ever increasing levels of carbon dioxide in the atmosphere. This process of increasing atmospheric CO 2 lowers the ocean’s pH value, resulting in more acidic waters. Biologist Maximilian Baum, pictured, leads this project at Heinrich Heine University Dusseldorf. In particular, we are interested in the Blacktip Reef Shark and how its teeth are able to survive in more acidic conditions.
Researchers collected over 600 discarded teeth from an aquarium housing Blacktip Reef Sharks to examine how varying pH levels affect tooth structure. The research underlines just how much sharks rely on their teeth, even in the hunting tooth machine that is a shark. Increasing ocean acidity threatens the physical integrity of these crucial tools for marine predators. This represents the single greatest danger to their continued existence.
The Study’s Methodology
The research took a close look at 16 Blacktip Reef Shark teeth that experienced pH treatments. The researchers then put these teeth into individual 20-liter tanks, where they incubated them for eight weeks. The teeth were exposed to two different pH levels: one at 7.3, representing more acidic conditions, and another at 8.1, reflecting current oceanic averages.
After an incubation period, researchers examined the teeth for signs of damage. The results were alarming. Teeth exposed to the 5.5 pH level experienced much higher levels of damage compared to the teeth kept at 8.1.
“We observed visible surface damage such as cracks and holes, increased root corrosion, and structural degradation,” – Prof Sebastian Fraune.
Changes in circumference were measured on 36 additional teeth. The study underlined the destructive impacts of acidic exposure.
Implications for Shark Survival
Most sharks can’t afford to risk the structural integrity of their teeth when targeting prey. So, any weakening of tooth quality from ocean acidification is a direct blow to their survival. For the health of marine ecosystems, Baum said it’s critical to keep oceans’ pH levels high.
“Maintaining ocean pH near the current average of 8.1 could be critical for the physical integrity of predators’ tools,” – Maximilian Baum.
The effects do not stop there… Baum emphasized that small decreases in pH may negatively affect other sensitive species that replace teeth over long periods, causing long-term cumulative impacts.
As sharks irremediably lose teeth, the energetic burden of repairing or regrowing them mounts. This effect is exacerbated in acidified waters.
“In living sharks, the situation may be more complex. They could potentially remineralize or replace damaged teeth faster, but the energy costs of this would probably be higher in acidified waters,” – Prof Sebastian Fraune.
Broader Environmental Concerns
This study brings to light a troubling environmental injustice. Climate change impacts are cascading through food webs, impacting entire ecosystems and the species that rely on them. Ocean acidification is not merely a localized phenomenon. It threatens various marine species and their interdependent relationships in ways that are still being understood.
“It’s a reminder that climate change impacts cascade through entire food webs and ecosystems,” – Maximilian Baum.
Shark teeth are composed of highly mineralized phosphates. Even when protected, they remain vulnerable to future ocean acidification, which can still erode the pavilion and damage them. This poses interesting questions regarding the adaptability of these top-level predators in quickly shifting habitats.
“Shark teeth, despite being composed of highly mineralized phosphates, are still vulnerable to corrosion under future ocean acidification scenarios,” – Maximilian Baum.
What began as a bachelor’s capstone project evolved into a peer-reviewed academic paper. This project has impressed upon us the amazing power of student research and the critical role it plays in solving pressing environmental challenges.
“This study began as a bachelor’s project and grew into a peer-reviewed publication. It’s a great example of the potential of student research,” – Prof Sebastian Fraune.