It was a cold, clear night when researchers decided they needed to conduct a large-scale survey and ecosystem study during the polar night. The researchers were on a small boat in the middle of a Svalbard fjord when they saw light produced by bioluminescent organisms in the water. “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,” said 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 added.
Not only is this ecosystem active, the diversity and reproductive activity of some species are higher during the winter than other times of the year. From the press release:
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.
And it wasn’t just marine life. What surprised researchers most were the seabirds. “Not only are they there, but they are able to find their preferred food in the total darkness,” says Berge. How do the seabirds do it? Berge and his colleagues aren’t sure. They just know they can.
Berge and his colleagues spent three consecutive winters collecting samples in Kongsfjorden, Svalbard – a Norwegian archipelago located between Norway and the North Pole. The team focused on the second half of the 117-day long polar night when biological activity was expected to be at its lowest.
The researchers observed continuous growth in bivalves (think clams, oysters and scallops), foraging seabirds and a constant circadian cycle in zooplankton and benthos during the polar night.
So, what do these findings mean? It means one of the more sensitive areas to changing climate is even more sensitive now that researchers know many species don’t go dormant during the winter.
“We can’t simply assume that the dark polar night is a ‘safe’ period when things are not turned on,” says Berge. “Rather, it turns out that the dark polar night is an important period for reproduction in a number of organisms, and, as such, it is probably more sensitive than other parts of the year.”
Plus, more research needs to be done. The study’s authors write that there have been several studies examining certain portions of the Arctic marine ecosystem during the winter, but their paper is the first to study the darkest period and focus on the entire ecosystem.