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The secret life in the dark

The comb jelly Beroe cucumis is one of many organisms that makes use of bioluminescence during the dark polar night. FOTO: Geir Johnsen

The secret life in the dark

When the sun disappears a fantastic light show ignites.

In the darkness all is black. Black sea, black sky and black landscapes. Life that has not fled south turns off the switch and waits for better times. Everything is cold, windy and dead. Or so folks thought. In recent years, scientists have started poking the surface of what could be a secret world that is teeming with colorful, strange life. Right in the Arctic, in the middle of the dark season, right under our noses.

"It's like opening a Pandora's jar," says Jørgen Berge, a professor of Arctic and marine biology at the University of Tromsø (UiT). "Almost any rock we turn, we find something new. Usually, we have believed that anything that can swim or fly away does it. But this is not so. The polar night is a period where you have an enormous amount of life up here. We were very surprised."

Plunging into the black mystery

Berge is sitting in the captain's cabin of the research ship Helmer Hanssen, named after the polar hero and ice-pilot who was with Roald Amundsen through the Northwest Passage and at the South Pole. The trawler is used by the university to explore various areas during its annual Outreach expeditions, including Billefjorden to comb the depths. Berge leans forward and gestures. A round table in the captain's cabin is the Arctic Circle, while the middle of the tablecloth represents 80 degrees latitude north.

"Inwards of here there are swells, plunging black darkness in wintertime," says Berge, who has been on several expeditions around the islands with this ship. "And this tablecloth covers almost the entire Arctic Ocean. It is a huge area and we have no idea really what's going on here in the winter."

"And it is said that only the Svalbard ptarmigan is overwintering, but this is not so. We see little auks and guillemots. Kittiwakes and fulmars. It is only when you turn off the light and go out in a small boat that you realize the air is full of life during the dark months."

Winter seabirds

The vast, vast majority of birds migrate south, he says. But a small percentage choose to stay behind. And it's not the "losers" who fail to get their wings on before the sun disappears, but the strategists. When most of their competitors are gone, there are good times for those who adapt to the dark.

"You could see for yourself if they were starving, but the ones we've captured are chock full of food," he says. "We took a Brünnich's guillemot that had 250 krill in its stomach. Another had plenty of bottom-dwelling amphipods. Some had eaten fish. But how they find food in darkness, that we have no idea."

A cosmos in the sea

Fat seabirds during winter requires a generous winter sea. Berge says the largest "a-ha" experience came during the polar night a few years ago when he was in Rijpfjorden at Nordaustlandet. A starry sky was suddenly reveled. Not above them, but beneath them.

"It was absolutely, totally dark, and then we saw this incredible blue biological light that appeared under the boat," he says. "Phosphorescence. Everyone fell silent. It was a revelation and we realized that this is something important to study. Something we don't understand. Rijpfjorden has been a sacred place for me."

In the fjords during the polar winter there are many major ribbed jellyfish, krill, copepods and unicellular organisms that trigger spectacular light shows.

"The proportion of organisms that are here in the dark season and produce light is very, very high," Berge says, now using mobile phones and soda cans on the table to show the balance in the food chain. "There are numerous hypotheses about why they do it. Some use it to communicate with one another, while others illuminate to attract prey. And some believe that by making light you attract your enemy's enemy. Then he will be eaten so you yourself can eat."

But where does the energy come from?

Spring explosion

The "normal" wildlife we see is totally dependent on the spring and the sun. Algae and plankton absorbs rays 24 hours a day, exploding in number and leading to a bonanza that extends from the bottom of the food chain. The bright months are a food orgy. Then it is closing time.

"And when the sun disappears, you have a system that does not get refills of new energy," Berge says. "In the polar night, it may seem as if the ecosystem is controlled from the top down, meaning that the mechanisms are snuffed. But there is very much we do not understand."

Long, strange little fish

Svetlana Pekkoeva, a PhD student, is engaged in a quest to find out how some species solve their energy needs in the extreme environment. She's researching the daubed shanny (Leptoclinus maculatus), a long, thin and strange little fish that is an enormously important puzzle piece in the Arctic picture.

"They are a keystone species in the ecosystem, and an important food source for many birds and other fish," says Pekkoeva, who works at the Department of Biology at the Russian Academy of Sciences in Moscow.

The daubed shanny, which by the way has nothing with the more famous famous lutefisk, solves the problems of the Arctic in a unique way. On the underside of their bodies, they have a small sac that stores up energy in the form of compounds called lipids. Some of these lipid sacs can be so large that they looks like beer bellies.

"I'm studying how they develop throughout the next year. What the contents of the lipid sacs are and what they eat. So far we have trapped them for several seasons, but we're lacking the summer month of July," says Pekkoeva as she rises.

"Now we will trawl. I have to prepare myself."

Up from the depths

After some initial problems with the technical and cursing among the crew, the trawl drops to the bottom of Billefjorden, a depth of 150 meters, for 15 minutes. The catch bag is emptied into a basin on the deck. Life scuttles about. Pekkoeva and Berge, who is her supervisor, go on a treasure hunt for daubed shanny among the among the quantities of herring, shrimp, amphipods, polar cod and other wonders the trawl swept up from the depths.

"These dark shannys are adults, while the glassy and transparent ones are juveniles," says Berge as they expertly and quickly sort out the animals they're looking for. And sure enough, the shannys have good and round lipid sacs.

One of them even stands out as "overweight".

"I've never seen anything like this before," Pekkoeva says of the creature's "stomach."

"They are eating so much food now in the summer. They are feeding constantly and that helps them to survive the winter," she continues as she prepares to preserve the fish for further analysis in the labs at home in Moscow.

Many mysteries

The secret life of the daubed shanny is about to be revealed, but they are only the surface of a dark-season ocean with more varied, spectacular and colorful life than anyone could have imagined.

The polar night's mysteries, right outside the windows here in the north, is one of the very last blank spots on Earth's map, Berge says.

He thinks the search has just started.

"I am absolutely sure that there is plenty we possibly don't know and that we will discover in the next few years," he says.

Se bildet større

Professor Jørgen Berge says the surface is barely scratched, and a whole world of exotic life is still to be found in the freezing cold and completely dark polar night. FOTO: Geir Barstein

Se bildet større

Professor Berge and phd student Svetlana Pekkoeva sifts through the trawl catch. FOTO: Geir Barstein

Se bildet større

The catch is mainly shrimp and herring, but the scientists find a few of the fish they are looking for. FOTO: Geir Barstein

Se bildet større

The daubed shanny (Lumpenus maculatus) stores up energy in lipid sacs. This adaptation helps it survive the harsh polar night. FOTO: Geir Barstein

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