Sharks' Teeth May Erode Under Acidifying Seas

Shark teeth - evolution's finely tuned cutting tools - show early signs of weakening as seawater pH levels shift. A German-led experiment found that teeth from blacktip reef sharks immersed in water with a pH around 7.3-an acidity projected by the year 2300 if carbon emissions continue unchecked-displayed significantly more structural damage than those in water at the current average of 8.1. Observations included widespread corrosion, surface cracks, and erosion from root to serrated crown, suggesting even these mineral-hardened organs are not immune to chemical degradation.

The experimental design involved over 600 naturally shed teeth, collected from an aquarium population of sharks. Researchers selected intact samples-16 teeth-to compare, and incubated them for eight weeks in controlled seawater environments, one reflecting present-day ocean acidity and the other simulating future acidified conditions. Key findings revealed about twice the damage in the lower-pH group: microscopic fractures, holes, and root erosion compromised surface structure and may extend to functional weakness.

Lead researcher Maximilian Baum of Heinrich Heine University Düsseldorf framed the problem starkly: these teeth were“highly developed weapons built for cutting flesh, not resisting ocean acid.” Even the crest and edges of the teeth, once razor‐sharp, were vulnerable to dissolution.

Though this research focused on non‐living mineralised tissue, hypotheses remain that living sharks may compensate by replacing or remineralising damaged teeth. Yet the energy cost of doing so under more acidic conditions could add metabolic strain to species already battling overfishing, habitat loss, and pollution.

Experts emphasise broader ecological implications. Dr Phil Hollyman of Bangor University noted that weakened dentition may reduce prey capture success and alter sharks' competitive edge within marine ecosystems.

Some species may fare better depending on their tooth replacement rate or dental anatomy. Sharks with fewer tooth rows or slower regenerative cycles could be at greater risk-making the potential hazard uneven across species.

The study, published in Frontiers in Marine Science, builds on previous literature showing acidification's impact on calcium‐rich marine life-such as corals, shells, and shark dermal denticles-drawing a through‐line from invertebrates to apex predators.

Given the likelihood that pH at global average levels could approach 7.3 by 2300 under high CO2 emissions, the findings underscore a lesser-known yet critical vulnerability within ocean ecosystems.

Researchers call for further work-particularly involving live sharks-to assess whether such chemical damage translates into diminished tooth performance or altered feeding behaviour. That knowledge is crucial for understanding how well sharks might adapt to persistent acid stress.

The unfolding picture raises pressing questions for marine conservation: can sharks maintain their role as efficient predators if even their most specialised biological tools are being chemically undermined?

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