Arctic marine life, down to 200 meters below the surface, is disturbed by artificial light from ships, according to a paper published this week in Communications Biology. These findings suggest that during the polar night, artificial light can affect population surveys, which can thus influence sustainable management efforts.
Fish and marine animals called zooplankton rely on cues from natural light to adjust their behaviour and migration patterns. Artificial light can both disorient these animals and disrupt the ecosystem, which can affect researchers’ ability to accurately observe marine life. However, the effects of artificial light on marine life are still poorly understood. This is especially true in the Arctic during the six-month long polar night, where fish and zooplankton have to rely on subtle, natural changes in nighttime light.
Jorgen Berge and colleagues measured how fish and zooplankton communities responded when exposed to artificial light from a ship during the polar night at three Arctic locations. They found that when a ship’s lights were turned on, the behaviour of animals changed almost immediately (within five seconds). Both the swimming behaviour and vertical position of animals, down to 200 meters below the surface, changed. The authors found that the effects of light on animal behaviour differed between the three sites. They observed the most dramatic behaviour changes at the northernmost site, where night is darkest.
The authors conclude that these findings should be taken into account when conducting future scientific surveys and stock assessments during the polar night.
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