During the long polar night, nature stays awake, study finds

Norwegian scientists say they’ve found unexpected levels of biological activity on the Svalbard Islands, an archipelago located along the 79th parallel, between Norway, Greenland and the North Pole. (IMAGE COURTESY OF UiT)

The phrase “in the dead of winter” is how some might describe Arctic regions at this time of year, especially people who experience continuous darkness from late November to early February.

But new research challenges the assumption that the polar night is a time of rest and inactivity for many species in the High Arctic.

Norwegian scientists say they’ve found unexpected levels of biological activity on the Svalbard Islands, an archipelago located along the 79th parallel between Norway, Greenland and the North Pole.

“The Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply,” says the new study, led by Jørgen Berge, a professor at University of Tromsø, an Arctic university in Norway.

“Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels.”

Researchers spent three winters studying the ecosystem in Kongsfjorden in the Svalbards, looking at species as small in size as micro-algae to the largest flying predators that inhabit the region.

The polar night in this region lasts for about 117 days; researchers collected data during the last half of that period, finding many species remained active during that time.

The area is known for its colonies of seabirds that are abundant in the summer months. But the researchers found a number of seabirds — auks, kittiwakes, guillemots and gulls — actively foraging for food throughout the polar night.

It’s not clear how these birds detect their prey in the dark, but when researchers studied the birds’ stomachs, they found a low degree of digestion, which suggests their diet is local.

The birds could be eating a large amount of tiny shrimp-like creatures, called krill, which are bioluminescent and could be detected in the dark, the study said.

Other smaller species, such as zooplankton and benthos — organisms that live on the seabed — also maintained their biological activities during the darkest months.

Contrary to the common belief that polar organisms synchronize their reproduction with the spring bloom of algae and other sea life, the researchers found evidence that the winter period serves as a major mating period for certain types of zooplankton.

“In some habitats, biological diversity and presence of juvenile states were elevated in winter months compared to the more productive and sunlit periods,” the study said.

Fish, such as herring and cod, were also eating well through the winter months, which the study’s authors say raises more questions about how these species sense their prey in the darkness of the polar night.

The study’s findings, that the ecosystem is not dormant during the polar night, is supported by another 2012 study that found activity within the plant and animal food web in Canada’s High Arctic.

“Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future management and decision making,” the Norwegian study concluded, “especially at a time when Arctic regions are experiencing accelerated environmental change.”