In a great example of life’s ability to flourish anywhere, a group of Antarctic fish evolved “anti-freeze” proteins that help them survive the frigid temperatures of the coldest continent’s waters. Now those fish are under threat from a problem they’ve never had to deal with: warming water.
A Yale study of the evolutionary history of Antarctic fish, published today in the Proceedings of the National Academy of Sciences, shows just how specialized these anti-freeze fish are, and how their advanced traits place them at risk of succumbing to climate change.
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“A rise of 2 degrees centigrade of water temperature will likely have a devastating impact on this Antarctic fish lineage, which is so well adapted to water at freezing temperatures,” lead author Thomas Near said in a statement.
The fish, known as notothenioids, flourished over millions of years into 100 distinct species. Thanks to an ancient period of rapid cooling, much of the fish in the then-warmer Southern Ocean went extinct. Notothenioids survived thanks to the fishes’ production of glycoproteins, which prevent their plasma from freezing. Over the centuries, the notothenioids diversified to fill the numerous ecological niches made available by the prior extinctions, and they now make up most of the fish biodiversity in Antarctic waters.
Because the anti-freeze fish are so common in southern waters, they are very important food sources for predators, like toothed whales, penguins, and seals. That food source is now under threat, especially considering that Antarctica is one of the fastest-warming areas on Earth.
“Given their strong polar adaptations and their inability to acclimate to warmer water temperatures, climate change could devastate this most interesting lineage of fish with a unique evolutionary history,” Near said.
As un-sexy as they sound — there’s a reason they’re oft referred to as ‘anti-freeze fish’ and not boring-sounding notothenioids — the fish are crucial to the Antarctic food chain. The fact that they’re at risk means that the aforementioned predators are likely at risk too. The whole notothenioid story thus serves as a great example that, ecologically speaking, no species is isolated, and negative effects to one group are likely to cascade through the rest of the ecosystem. So even if penguins didn’t mind warming weather — though they likely do — they’ll certainly care when their food supply dwindles.
