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Green and red lights reflecting on the sea

Green and red lighting might be good for migratory birds and sea turtles, but could have undesirable effects if marine algae are present. Credit: Getty


Red light, green light: both signal ‘go’ to deadly algae

Artificial lighting thought to be more wildlife-friendly than white light could encourage algal blooms.

Green or red lights in seaside areas have been proposed as alternatives to white light to protect wildlife. But new experiments show that exposure to red or green light at night boosts the growth of some ocean algae — including species known to rob waters of oxygen.

Little is known about the impact of artificial light on marine life, even though many brightly lit cities are coastal. To address that knowledge gap, Sofie Spatharis at the University of Glasgow, UK, and her colleagues exposed a mix of microscopic marine algae collected from Scottish waters to standard white light. They also exposed the mixture to red and green lights, which have been proposed to minimize impacts on sea turtles and migratory seabirds, respectively.

The team found that all light colours enhanced growth of the microalgae mix. Red light had the most pronounced effect, doubling the number of cells produced. The proportions of species in the mixture also shifted: both red and green light especially favoured growth of harmful species in the Skeletonema genus, which form dense blooms that are deadly to fish.

More Research Highlights...

Selected materials found in the gut contents of Tollund Man

The intestinal contents of a man killed in a prehistoric ritual (clockwise from upper left): barley, charred food that had been encrusted in a clay pot, flax seeds and sand. Credit: Peter Steen Henriksen, the Danish National Museum


The guts of a ‘bog body’ reveal sacrificed man’s final meal

Tollund Man, who lived more than 2,000 years ago, ate well before he was hanged.
Illustration of Earth with white lines showing the magnetic field.

Earth’s magnetic field (depicted as white lines in this artist’s impression) can be studied with observations from a constellation of commercial satellites. Credit: Mikkel Juul Jensen/Science Photo Library


Telecoms satellites’ new purpose: spying on Earth’s magnetic field

Clues to the forces generated by the planet’s core emerge from observations intended for satellite navigation.
Ageing of an artwork with graphene

After 130 hours of artificial ageing by visible light, the painting Triton and Nereid has lost some of the purple tint to the figures’ right, but a graphene film kept the bright pink at upper left undimmed. Credit: M. Kotsidi et al./Nature Nanotechnol.

Materials science

A graphene cloak keeps artworks’ colours ageless

A layer of carbon atoms preserves a painting’s vibrant hues — and can be applied and removed without damage.
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