Warmer Antarctic May Help Humpbacks, Harm Seals, Penguins

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In future summers, humpback whales may swim further into the Ross Sea, the body of Antarctic waters on the South Pacific side of the continent, as sea ice decreases. But many other animals may suffer as ice cover reductions alter the base of the Antarctic ecosystem, warned oceanographers in a recent study.

The marine scientists forecast a potential 56 percent decrease in summer Ross Sea ice extent by 2050 and a 78 percent reduction by 2100. The mingling of deeper, cooler water with surface water may also decrease during future Antarctic summers.

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The depth of this mixed layer may decrease by 12 percent by 2050 and 44 percent by 2100, as wind current change over the Ross Sea. The journal Geophysical Research Letters published these results.

The changes in sea ice extent and water mixture will likely cause dramatic shifts in the Antarctic ecosystem. Overall productivity of the Ross Sea may increase by approximately 14 percent. However, the future Antarctic marine community may become dominated by different species than those currently present.

A major domino to topple the Ross Sea ecosystem may be a future reduction in the population of crystal krill (Euphausia crystallorophias), a tiny species of crustacean. Cold-loving crystal krill currently dominate base of the Ross Sea food chain, but may decline without summer sea ice. The krill feed numerous Ross Sea predators, including minke whales, Adélie penguins, emperor penguins, and crabeater seals.

All of these animals will likely suffer as the crystal krill die off, warned the study’s authors. Adélie penguins may also have to swim further through leopard-seal-infested waters to reach another food source, Antarctic silverfish.

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Other species could benefit from the changing Antarctic. In a warmer Ross Sea, different diminutive creatures, algae species known as diatoms, could be come more common. Diatoms serve as food for copepods, small crustaceans, which may also increase in numbers. On the other end of the size spectrum, humpback whales may also swim further into the Ross Sea as more of the summer sea loses its ice and the productivity of the Ross Sea rises.

Image: Emperor penguin, Aptenodytes forsteri, chick with parent In Ross sea (Brocken Inaglory, Wikimedia Commons