Bright lights big city: do energy-efficient LED lights cause unexpected ecological damage?

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Insect attraction to street lamps in Tudela, Spain (creative commons license).

Insects are attracted to narrow range UV lights, based on the evolved sensitivities to UV light in their eyes. Some birds are adapted to only sing mating calls at night based on the light quality from a full moon. High light levels can increase the mating behaviors of some frogs and changes in the quality of light can affect bird nesting behaviors. With so much of the natural world dictated by fine-tuned associations with light quantity and quality, how does the constant light pollution of cities affect the behavior of these organisms?

Many cities worldwide have begun to shift towards LED light bulbs in streetlights due to improved color rendering (broader spectrum light quality) and increased energy efficiency over time. However, changes in light quality and quantity resulting from widespread changes in streetlight bulbs will almost certainly affect urban populations of plants and animals as well.

One study demonstrated that bat populations in suburban areas of the UK were unaffected by a switch from low-pressure sodium (LPS) bulbs to higher efficiency LED bulbs.

Past work in New Zealand indicated that a switch to LED lights can increase insect attraction to artificial lights by as much as 48% when compared to high-pressure sodium (HPS). Conversely, a study in Germany showed increased attraction to HPS over LED lighting. The picture isn’t yet clear.

In the design of sustainable cities the question probably has to be: How do we design lighting solutions that reduce rapid changes from the status of the past several decades. This will mean that we aren’t suddenly applying a new environmental filter that affects plants and animals in entirely new and different ways. At the very least this should reduce environmental variability, and will likely lead to more ecological stability over time.

shared via: blogs.plos.org/ecology/2016/03/24/bright-lights-big-city-do-energy-efficient-led-lights-cause-unexpected-ecological-damage/

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