Light pollution giving toads sleepless nights
Lighting from cars, buildings and streetlights is keeping toads up at night and stunting their growth, while also preventing frogs from laying their eggs, according to a new study. In populations of amphibians that are already in severe decline thanks to toxic chemicals, diseases and habitat destruction, the disturbance caused by light pollution could be pushing them over the edge.
Artificial lights have transformed the night-time environment across a fifth of the planet’s surface and this is expected to increase rapidly in coming years. Despite the scale of this disturbance, little is known about its impact on the animals whose habitats have been changed by 24-hour lighting.
This was noted by Kacey Dananay, a graduate student at Case Western Reserve University College, who began considering the impact of artificial lights while investigating the effect of chemicals from road salt on amphibians. She began working on a project with ecologist Michael Benard, in which artificial ponds were constructed the effects of constant light on toads were observed. "If we continued exposing them to artificial light they changed their behaviour so they were active more at night, and they also had slower growth — about 15 per cent smaller at the end of the experiment," Benard said.
The scientists found their experiments were invaded by local treefrogs. While the frogs were happy to lay their eggs in darkness, they avoided lit-up pools, suggesting that amphibians are being driven from their breeding grounds in areas subject to constant illumination. These results were published in ‘Proceedings of the Royal Society B’.
Artificial lights have transformed the night-time environment across a fifth of the planet’s surface and this is expected to increase rapidly in coming years. Despite the scale of this disturbance, little is known about its impact on the animals whose habitats have been changed by 24-hour lighting.
This was noted by Kacey Dananay, a graduate student at Case Western Reserve University College, who began considering the impact of artificial lights while investigating the effect of chemicals from road salt on amphibians. She began working on a project with ecologist Michael Benard, in which artificial ponds were constructed the effects of constant light on toads were observed. "If we continued exposing them to artificial light they changed their behaviour so they were active more at night, and they also had slower growth — about 15 per cent smaller at the end of the experiment," Benard said.
The scientists found their experiments were invaded by local treefrogs. While the frogs were happy to lay their eggs in darkness, they avoided lit-up pools, suggesting that amphibians are being driven from their breeding grounds in areas subject to constant illumination. These results were published in ‘Proceedings of the Royal Society B’.