A unique group of fish that has evolved to live in Antarctic waters thanks to “anti-freeze” proteins in their blood and body fluids is threatened by rising temperatures in the Southern Ocean, according to a new
study. Yale University researchers say that the more than 100 species of so-called icefish, or notothenioids, evolved 20 million to 40 million years ago to live in waters as low as -2 degrees C, which is the freezing point of saltwater. The notothenioids account for the bulk of fish diversity in the waters around Antarctica and are an important source of food for penguins, seals, and toothed whales. But as water temperatures rise in the Southern Ocean — some Antarctic water temperatures have increased by .5 degrees C in the past several decades — the notothenioids may have trouble adapting to a warmer environment, said the study, published in the Proceedings of the National Academy of Science.Â “A rise of 2 degrees centigrade of water temperature will likely have a devastating impact on this Antarctic fish lineage,” said Thomas Near, associate professor of ecology and evolutionary biology at Yale.