Arctic's Frigid, Dark Winter Causes Marine Creatures to Migrate by the Light of the Moon
During the Arctic winter, darkness reigns in the icy north. Now, scientists have found that the creatures living within on Arctic fjord keep busy even during these frigid months. Scientists have found that instead of using sunlight, the tiny marine animals use moonlight to drive their vertical migrations in the ocean.
"During the permanently dark and extremely cold Arctic winter, [these] tiny marine creatures, like mythical werewolves, respond to moonlight by undergoing mass migrations," said Kim Last, one of the researchers, in a news release.
No matter where the researchers looked during the Arctic winter, they observed the same behavior. Further investigations showed that marine creatures shifted their activities from following the 24-hour solar day to following the 24.8-hour lunar day.
"The most surprising finding is that these migrations are not rare or isolated to just a few places," said Last. "The acoustic database used for our analysis cumulatively spans 50 years of data from moorings that cover much of the Arctic Ocean. The occurrences of lunar migrations happen every winter at all sites, even under sea ice with snow cover on top."
The findings have implications for the carbon cycle, since the migration contributes to the carbon pump by moving fixed carbon from the surface into the deep ocean. Since there is no photosynthesis during the polar night, carbon is only moved into the deep by predators feeding on prey.
The findings reveal a bit more about this winter migration, which may allow researchers to better estimate the movement of carbon.
The findings are published in the journal Current Biology.
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