At night, tiny marine animals such as Arctic zooplanktons continue to migrate using the light from the moon, a new study confirms. Moonlight drives the migration of marine animals through permanently dark and frigid Arctic winter.
In the study published in the Cell Press journal Current Biology, researchers reported the surprising discovery that marine creatures are busy even during the cold dark winter months. Even in the absence of sunlight, the moon guides the migration of these little aquatic animals.
Based on data gathered from moored acoustic instruments, wintertime lunar vertical migration (LVM) was found to be controlled by the moon's phase and altitude above the horizon. It occurs not only in portions, but across the whole Arctic Ocean.
The researchers also found a mass of zooplankton from the surface waters sinking to 50 meters (164 feet) every 29.5 days during winter, which coincides with the full moon. They also observed that instead of following the 24-hour solar day, marine animals shifted to the 24.8-hour lunar day.
Moonlight was speculated to play a major role in structuring predator-prey interactions during winter. The behavior is most likely an attempt by tiny marine animals like zooplanktons to avert predator hunting by moonlight.
"The LVM-month behavior is coincident with the time of the full moon and typically involves movement to deeper water for a few days, the reason for which is hypothesized to be avoidance of visual predators capable of utilizing the lunar illumination to hunt," the study said.
The findings may shed light in the carbon cycle that happens during this season in the Arctic sea. Since photosynthesis is absent during the winter months and polar nights, carbon only moves into the deep by predators feeding on prey.
"The daily vertical migration of zooplankton contributes significantly to the carbon pump by moving fixed carbon from the surface into the deep ocean," explained Kim Last of the Scottish Association for Marine Science in Scotland.
The researchers claim that the movements of zooplanktons during winter could become even more prevalent as climate change and ice melts continue to increase. However, they are uncertain as to what type of effects this type of migration can cause.
"In summary, we present compelling evidence of zooplankton migrations during the polar night across the Arctic Ocean, in fjords, on the shelf, slope, and open sea across 21 degrees of latitude. This finding is consistent at all locations of the pan-Archive.," the researchers said.
Photo:Paul Bica | Flickr