You might expect that little happens in the Arctic Ocean during the cold and dark winter. But that just isn't so, according to researchers who have sampled the activities of many different species during three consecutive winters in Kongsfjorden, Svalbard. Their findings are published in the Cell Press journal Current Biology on September 24. "This once and for all changes the way we think of marine ecosystems during the polar night," says Jørgen Berge of UiT The Arctic University of Norway and the University Centre in Svalbard.

"The dark polar night is not a period without any biological activity [as had been assumed]. Concealed behind the curtain of darkness is a world of activity, beauty, and ecosystem importance."

Berge says the researchers were inspired to look more closely at what happens during the polar night based on a chance encounter they had on a small boat in the middle of a Svalbard fjord.

"Above us was a starry, winter night and below us were countless blue-green 'stars' in the deep" produced by bioluminescent organisms, Berge says. "The beauty of it was stunning, and the fact that so many organisms were producing light was a strong indication that the system was not in a resting mode."

He decided then and there to do a large-scale survey and ecosystem study of the polar night in one of the Svalbard fjords during three consecutive winters. Instead of an ecosystem that had entered a resting state, the researchers say they found a system buzzing with biological activity. In fact, the diversity and reproductive activity of some species was actually greater during the winter than at other times of the year.

The researchers found, for instance, that copepods and other zooplankton were actively reproducing as filter-feeding Iceland scallops kept right on growing. Baited traps with time-lapse cameras revealed an abundant and active community of shallow-water scavengers, including whelks, amphipods, and crabs.