Pollution of the Arctic with light affects fish and zooplankton to a depth of 200 m. This is the conclusion made by scientists from the Arctic University of Norway, who studied the reaction of marine animals to light during the polar night. The work was published in the journal Commun Biol.
Arctic polar night is the period during which the sun remains below the horizon for the entire 24-hour cycle. It was dark in the Arctic at this time: until now it was believed that the lack of light made marine organisms inactive during this period.
Nevertheless, scientists already knew that during the polar night life in the sea does not freeze – observations have shown that birds continue to hunt for fish and zooplankton, which has the properties of anti-luminescence.
In a new study, scientists determined how much light a marine organism needs to change their behavior during this period. The work showed that some animals become more active when exposed to light, the intensity of which is only one millionth of the day. These include algae cells, which, when irradiated, quickly turn into a photoactive state.
“We were able to document light-controlled biological processes that are still ongoing during the polar night. Many species of fish and zooplankton remain active and migrate vertically in the water column for 24 hours. These migrations are fully regulated by small changes in sunlight or moonlight. Even the light of a research vessel or a vessel evaluating the size of the stock of zooplankton and fish can affect organisms at a depth of 200 meters below the surface of the ocean”.
Jorgen Berge, lead author of the study