Copepod is “keystone Arctic species” as indicator of climate change

In an article in the October 2014 edition, The National Geographic reports on Franz Josef Land in the Arctic Circle. This archipelago of islands is a nature reserve under Russian law and host to a wide range of Arctic animal species, in particular, the little auk.

Little auk

Little auk
Photo: Hallvard Strøm / Norwegian Polar Institute

The National Geographic reports: “The little auk feeds primarily on copepods, minuscule crustaceans that are the main component of Arctic zooplankton. Each bird needs to gobble thousands of them to make a square meal. “And these copepods, they have very specific temperature preferences,” Grémillet explains. “So you can predict that if these copepod communities change because of climate change in the Arctic, the little auks will show a strong response.”

How might the copepod fauna change? One of the larger and fatter kinds, Calanus glacialis, depends upon very cold water and the presence of sea ice, beneath which grow the algae that it eats. A smaller and leaner species, Calanus finmarchicus, is common in the North Atlantic and often rides currents into the Arctic but doesn’t flourish there.

Photo: EOL (Encyclopaedia of Life)

Photo: EOL (Encyclopaedia of Life)

As the Arctic Ocean warms by a few degrees, though, the competitive balance could shift. Higher temperatures and decreases in sea ice could allow the small, lean copepods to replace the big, fat ones, to the detriment of the little auk — and of other creatures as well. Arctic cod, herring, and various seabirds feed on the copepods, and even such mammals as ringed seals and beluga whales depend on fish that feed on them. That’s why scientists consider Calanus glacialis a keystone species in the Arctic.

Source: The National Geographic, October 2014. For the full text see http://ngm.nationalgeographic.com/2014/08/franz-josef-land/quammen-text

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