The rise in ocean temperatures is wreaking havoc on fish that reside in the Antarctic. Because of the increase, the fish, accustomed to polar living, no longer are able to cope.

A recent study by Yale researchers have looked at the evolutionary history of Antarctic fish. These fish house “anti-freeze” proteins, which, as their name suggests, are impervious to freezing in the, well, freezing waters. Millions and millions of years ago, these fish adapted to the polar conditions; however, today they are endangered because of the rapid rise in ocean temperatures.

Thomas Near, the associate professor of ecology and evolutionary biology, as well as the lead author of the study, explains that the 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.”

These fish have successfully been developed and diversified into a hundred species of different fish. Collectively called the notothenioids, they adapted through the years to their different habitats in order to thrive. Millions of years ago, the rapid cooling led to a mass extinction of the fish that were living in and accustomed to the warmer waters. However, the acquisition of these ” anti-freeze” glycoproteins allowed the notothenioids to be able to survive in waters that were home to these frigid temperatures. Over the years, the notothenioids adapted to the different open ecological niches, and soon, as evolution dictates, there were new species of notothenioids that came to fruition, and soon were a part of the regular marine life living within the waters of Antarctica.

Notothenioids are the main species of the fish that are found to have thrived through this lineage. They are also a major food source for larger predators, such as whales, seals, and penguins. There are other species of fish as well, that are an example of the changes and difference of lineage that have been determined by the temperature of the water and environment that they live in.

The new study suggests that although the notothenioids had the ability to gather these anti-freeze glycoproteins about 42 million years ago, this was not the only reason that the notothenioids were able to successfully adapt to their Antarctic surroundings. In fact, the largest amount of the notothenioids fish species falling into new habitats began to occur about 10 million years following the first appearance of the anti-free glycoproteins, which is what the study has discovered.

Interestingly, it was also as a trigger instead. “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 explained in the study.

The problem is that the success seen here from evolution and the natural state is threatened by the climate change, especially in Antarctica and the other areas in the Southern Ocean, primarily because this is one of the fastest-warming regions on the Earth. These same traits that allowed the fish to be able to survive and live in the rapidly cooling earth have made them particularly vulnerable to the issues in the earth that is warming. The study explains that since they were so able to adapt to the strong polar conditions, they have an opposite ability to acclimate to the warmer water temperatures. Because of this, climate change could devastate and wipe out this lineage of fish, which have offered a uniqueness in evolutionary history. Furthermore, it will provide lack of a food source for the whales, seals, and penguins

The study published online this week in the Proceedings of the National Academy of Sciences.

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