Arctic Crustaceans Use Currents, Deep-Water Migration to Survive Ice Melting

Crustaceans that used to dwell on the underside of the sea ice were recently noticed migrating to deep waters and follow ocean currents back to colder areas when ice disappears.

This alteration is occurring due to the rapid melting of Arctic sea ice. The marine animals are facing dramatic changes to the environment.

"Our findings provide a basic new understanding of the adaptations and biology of the ice-associated organisms within the Arctic Ocean," said Mark Moline, director of the University of Delaware's School of Marine Science and Policy in the College of Earth, Ocean, and Environment. "They also may ultimately change the perception of ice fauna as imminently threatened by the predicted disappearance of perennial sea ice."

Moline, Jorgen Berge of the University of Tromso and Norwegian colleagues determined that the crustaceans migrate downward as part of their life cycles and ride deep-ocean currents toward the North Pole. They discovered this during their research expedition to the Fram Strait and Eurasian section of the Arctic Ocean.

The crustaceans' travels appear to be an adaptive trait that both increases survival during ice-free periods and enables them to be retained in the Arctic Ocean.

The researcher refer their findings were referred as "Nemo hypothesis",based on the Disney movie Finding Nemo in which Nemo's father uses deep-ocean currents for transportation. Similarly Arctic Crustaceans move from melting sea into depths where the northernmost branch of the Gulf Stream System effectively transports them back into the Arctic Ocean.

"Through the Nemo hypothesis, we offer a new and exciting perspective that, although still based on a limited dataset, might change our perception of the ice-associated organisms and their future in an Arctic Ocean potentially void of summer sea ice within the next few decades," Berge said.

This study will help the researchers to understand how the ice-associated organisms can survive in large populations in the Arctic when their habitat is altered due to the summer.

"We believe that this is an important contribution towards a more comprehensive understanding of potential consequences of a continued warming of the Arctic and the predicted loss of summer sea ice," Berge said.

The findings were carried in the biology Letters Online on Sept. 12.