Even in the Arctic ocean in the long polar winter, life goes on. Brrrr!
Quote:The Arctic after dark: a secret world of hidden life
An international team braved the far north in January to unlock secrets of how marine organisms tell day from night during the polar winter.
I bet it was rather colder than Tassie in winter, contrary to the opinion of a couple of idiots.
Quote:. . . A series of discoveries has shown that even in the absence of sunlight and food, some zooplankton thrive throughout the winter. They mate and incubate eggs in the darkness — and all that activity plays a crucial part in fuelling the Arctic’s massive explosion of rebirth each spring.
How to study this tho:
Quote:Researchers are eager to get answers, because the Arctic is changing rapidly. Over the past four decades, the region has warmed nearly four times faster than the rest of the planet1, and its winter coating of sea ice is thinning rapidly, which means there is less ice throughout spring and summer. At the same time, the retreat of the ice pack has opened routes for shipping, tourist cruises and coastal development that all add light pollution to the region. The combined changes mean that increasing levels of light are seeping into the Arctic Ocean, even during winter, which could forever alter the ecosystem that has evolved to take advantage of the darkness.
There is some thick ice off the coast of the Canadian Arctic Archipelago (CAA) but not nearly as thick as ice was before 1980. The ice off the CAA harbors the largest concentration of polar bears—polar bears are doomed and will have to adapt to life on land not ice.
Quote:In the darkness
It was a chance discovery that set all this research in motion. In 2006, Berge visited the Svalbard archipelago, mountainous Norwegian islands several hundred kilometres east of Greenland’s northernmost coast, to moor instruments in a fjord during the autumn. He had to get the equipment in place before the fjord’s waters froze in the winter, so he could record the rebloom of life beneath the ice the following spring.
But when he retrieved data from the mooring the next year, he noticed a mysterious pattern during winter. A sonar instrument revealed that biomass in the fjord’s waters dropped to lower depths during the day and ascended towards the surface at night — a signal that marine biologists call diel vertical migration (DVM)2. But that shouldn’t have happened in the dead of polar night, when the Sun doesn’t rise above the horizon.
“It was an accident, a complete surprise,” he recalls
A surprise that life was active, not hibernating, in the cold of the Arctic winter. With so much ice melting, with so much Arctic Ocean exposed to sunlight in summer, absorbing it and being warmed by that sunlight I guess life could stay active.
The other surprise—how did ocean critters know the day/night cycle when they didn’t get any clues? Sun does not rise above the horizon in the depth of Arctic winter!
Quote:Nearly a decade after Berge’s first discovery, he and his team had another epiphany in this same fjord aboard Helmer Hanssen: their methods for studying marine life were disrupting it. They noticed that the DVM they were detecting from on board our ship was significantly weaker than the one detected by automated instruments left unattended during the winter3. They wondered whether light was the reason.
In 2016, bioacoustics specialist Maxime Geoffroy drove a skiff as far from Helmer Hanssen as he dared, and flipped on his headlamp, aiming it straight into the black waters. He watched in amazement as an echosounder showed biomass instantly dispersing in all directions down to 80 metres, even in the weak beam of a single headlamp.
“It opened a whole can of worms,” says Geoffroy, who works at the Memorial University of Newfoundland in St John’s, Canada. “What we were looking for at first was the physiology of these organisms in the pristine polar night, but we were removing the pristine part of it by coming with our big ship full of white lights.”
More and more ships travel the Arctic Ocean these days with so little thick ice left, with so much open water—even at the geographic North Pole, in summer. Freighters and cruise ships, oil exploration vessels etc etc now the ice is largely gone—lots of light pollution.
Quote:. . .Geoffroy and his colleagues focus on both technology and biology by lowering nets and circular steel frames called rosettes, brimming with optical and acoustic instruments, into the sea. These record reactions of marine life in this remote Svalbard fjord to a lights-off, lights-on protocol — successive passes with deck lights doused, followed by more passes with lights glaring.
Small boats launch from the harbour with instruments such as a marine light meter to track the rise and fall of daylight, invisible to human eyes in the heart of polar winter. . . .
cont’d
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Life in the dark (Read 43 times)
