From Yale University: Fish of Antarctica threatened by climate change
A Yale-led study of the evolutionary history of Antarctic fish and their “anti-freeze” proteins illustrates how tens of millions of years ago a lineage of fish adapted to newly formed polar conditions – and how today they are endangered by a rapid rise in ocean temperatures.
“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 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.
Notothenioids account for the bulk of the fish diversity and are a major food source for larger predators, including penguins, toothed whales, and seals. Yale’s Peabody Museum of Natural History has one of the most important collections of these specimens in the world.
However, the new 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, notes Near.
“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.
Yale-affliated authors of the study are Alex Dornburg, Kristen L. Kuhn, and Jillian N. Pennington.
I have to wonder though, what warming/climate change in Antarctica?
Maybe they are thinking of the surface record on the peninsula, where the greatest concentration of research stations, people, and energy use is. The air temperature there shows an increase.
But sea temperature near the peninsula doesn’t seem to be on the rise:
Or maybe they’ve spent too much time looking at Eric Steig’s graph:
Real Climate’s Dr. Eric Steig’s version, 2009 – from the cover of Nature
Instead of the one from 2004 before the Mannian PCA team math was applied to it:
Of course we now know thanks to O’Donnell et al that the whole “Antarctica is warming” theme from Steig and the team was just another statistical fabrication of air temperature.
Condon and O”Donnell’s Antarctic temperature profile, 2010.
It seems all the warming is in the peninsula, in the air temperature record, where all the people and energy use to keep them warm is.
Antarctica as a whole is not warming much at the surface, and as the UAH lower troposphere graph shows, not at all above the surface.
Antarctic sea ice seems to agree, it has an upward trend:
Joshua Corning makes an excellent point in comments:
“tens of millions of years ago a lineage of fish adapted to newly formed polar conditions”
“A rise of 2 degrees centigrade of water temperature will likely have a devastating impact on this Antarctic fish lineage”
That is weird…one wonders how they survived the far greater temperature changes over the past 20 million years.
You know…when Antarctica melted then froze gain….(image from Wikipedia)