Climate change near the arctic means a loss of sea ice, but in the depths of the ocean, that ice loss could fuel biological activity.
University of Delaware’s Jonathan Cohen and colleagues have been examining biologically produced light north of Norway during the Arctic polar night - the darkest time of year.
They’ve recently published a paper in Scientific Reports about ecological activity below the depths of the ocean during the winter. The paper indicates light reaches 100 feet below the ocean’s surface during the Arctic polar night; what they've noticed is despite the darkness, a community of biolumiescent, or light-producing organisms seems to be blooming 100 feet below the ocean's surface.
As ice continues to thin over time due to climate change, Cohen said researchers are now interested in how that will affect that ecosystem.
“One of the major predictions is that there’s going to be more light that makes it into the water column because there’s less snow and less ice for the light to have to go through, which really knocks down the light level tremendously,” Cohen said. “So when you have open water you have more light that makes it into the water, which can then fuel biological activity.”
Cohen said bioluminescence can explain how these organisms feed and stay active during the polar night period.
“That’s really well established for the deep sea, where bioluminescence is very common,” Cohen said. “And that’s sort of another thing that comes up in this paper is what we’re seeing in very shallow waters during the polar night is really a deep sea-like system in very shallow water.”
Cohen and his colleagues are exploring the relationship between light from the atmosphere and bioluminescence. They want to know how much light reaches below the ocean's surface and how organisms can use it to spot predators or prey.
During the Arctic polar night, there’s not much natural light that penetrates the sea ice, other than moonlight during times of a full moon, Cohen said.
There’s also no skylight available for organisms 100 feet deep in the ocean, so they need to rely on light they produce to find food or avoid predation.
Journal reference: Heather A. Cronin, Jonathan H. Cohen, Jørgen Berge, Geir Johnsen & Mark A. Moline. Bioluminescence as an ecological factor during high Arctic polar night. Scientific Reports, 2016, 6: 36374. DOI: 10.1038/srep36374.
