Currents used by crustaceans to survive ice melts14/09/12Environment
Norway/USA: The results of a new study on the habitat changes facing some arctic marine animals due to climate change and the melting of sea ice have shown that some crustaceans, previously thought to spend their entire lives on the underside of sea ice, migrate deep underwater and follow ocean currents back to colder areas when ice disappears.
The research team – conducted by Mark Moline, director of the University of Delaware’s School of Marine Science and Policy in the College of Earth, Ocean, and Environment, USA, and Jørgen Berge of the University of Tromsø, along with other Norwegian colleagues – found the crustaceans, specifically the amphipods Apherusa glacialis, which resemble small shrimp, well below sea ice during a rare winter night-time research expedition to the Fram Strait and Eurasian section of the Arctic Ocean.
They determined that the crustaceans migrate downward as part of their life cycles and ride deep-ocean currents toward the North Pole.
The scientists refer to their findings as the ‘Nemo hypothesis’, based on an analogy to the Disney movie Finding Nemo, in which Nemo’s father uses deep-ocean currents for transportation.
Moline said: “Our findings provide a basic new understanding of the adaptations and biology of the ice-associated organisms within the Arctic Ocean. They also may ultimately change the perception of ice fauna as imminently threatened by the predicted disappearance of perennial sea ice.”
Berge added: “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.
“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.”
The findings may help explain how ice-associated organisms can survive in large populations in the Arctic when their habitat is annually reduced by up to 80% in the summer, before re-forming in the early winter.
The research has been published in the journal Biology Letters.