Acidifying oceans could eat away at sharks’ skin and teeth

Hopefully the moonshark (and its ocean-ly ilk) can be saved from this pollution scourge.

For hundreds of millions of years, sharks have been roaming Earth's oceans making meals out of a huge range of critters, from the whale shark gobbling up tiny krill to the 60-foot megalodon that could take down whales. Their ancestral line has survived mass extinctions with ease, most notably the catastrophe that took down the dinosaurs.

But nothing could have prepared them for the scourge that is humanity-we're polluting their waters and snatching up their prey and hunting them to extinction. And now, thanks to climate change, humans may be transforming the very water sharks swim into an existential threat: In findings published today in the journal Scientific Reports, researchers show that prolonged exposure to acidified water corrodes the scales, known as denticles, that make up a shark's skin. To be clear, this work was done in the lab and on only one species, but the implications are troubling. As we belch still more CO₂ into the atmosphere, which reacts with seawater and makes the oceans more acidic, the seas themselves could become yet another threat that pushes sharks over the brink.

These days, the oceans on average have a pH of 8.1, making them 25 percent more acidic than in pre-industrial times. The lower the number, the more acidic the water, so 1 is a strong acid (think battery acid) and 14 is a strong base (milk of magnesia clocking in around 11).

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