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Global warming: Ocean warming threatens Antarctic fish

The development of antifreeze glycoproteins by notothenioids, a fish family that adapted to newly formed polar conditions in the Antarctic millions of years ago, is an evolutionary success story. Now the same fish are endangered by warming of the Antarctic seas. PHOTO COURTESY YALE UNIVERSITY.

The same evolutionary adaptation that enables fish to thrive in icy waters could be their downfall

By Summit Voice

SUMMIT COUNTY — Rapidly rising ocean temperatures around Antarctica are likely to imperil fish species that evolved eons ago with special antifreeze proteins that enable them to survive in icy waters.

The fish, known as notothenioids, account for the bulk of the fish diversity and are a major food source for larger predators, including penguins, toothed whales, and seals.

“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,” said Yale University’s Thomas Near, associate professor of ecology and evolutionary biology and lead author of the study published online the week of Feb. 13 in the Proceedings of the National Academy of Sciences.

The successful origin and diversification into 100 species of fish, collectively called notothenioids, is a textbook case of how evolution operates. A period of rapid cooling led to mass extinction of fish acclimated to a warmer Southern Ocean. The acquisition of so-called antifreeze glycoproteins enabled notothenioids to survive in seas with frigid temperatures. As they adapted to vacant ecological niches, new species of notothenioids arose and contributed to the rich biodiversity of marine life found today in the waters of Antarctica.

The Yale study suggests the acquisition of the antifreeze glycoproteins 22 to 42 million years ago was not the only reason for the successful adaptation of the Antarctic notothenioids. The largest radiation of notothenioid fish species into new habitats occurred at least 10 million years after the first appearance of glycoproteins, the study found.

“The evolution of antifreeze was often thought of as a ‘smoking gun,’ triggering the diversification of these fishes, but we found evidence that this adaptive radiation is not linked to a single trait, but to a combination of factors,” Near said.

This evolutionary success story is threatened by climate change that has made the Southern Ocean around Antarctica one of the fastest-warming regions on Earth. The same traits that enabled the fish to survive and thrive on a cooling earth make them particularly susceptible to a warming one, Near said.

“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.

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7 Responses

  1. An evolution that was a response to previous Antarctic cooling, might be threatened by warming. Does anyone else wonder that if enough warming occurs, an analogous evolution may also occur?

  2. Evolution in response to stimuli likely works in both directions. Are you confident of a timeframe we should be conceded about one temperature direction or the other?

  3. More alarmism nonsense

  4. Considering that we as humans are spectators to the ever changing events of today, we just may see how this plays out? As evolution goes, could we also speculate the fate of the present day human[s] in this too?

  5. Humans would likely adapt. Always thought it interesting when alarmists spoke of rapidly rising ocean levels in a manner suggesting we’d drown. Those humans that stayed and drowned would make the Darwin awards.

    Ice packs around the globe have ebbed and waned historically, over geologic time and within recent time. Certainly, we’ll continually see evolutionary responses to climate change – as the earth has for eons and man has for centuries. The alarmism is disingenuous. Interesting article, though.

  6. Another thought – might we here in the Rockies also see the demise of the pine beetle whose larva also have a glycol-based life fluid that protects it from freezing environments? Seems that such might be a good thing.

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