Street lighting 'could have dramatic effect on wildlife'

It's an indisputable fact that our nights should be dark – and when we alter natural conditions, some changes can have far-reaching and unexpected results.

A groundbreaking study by a University of Exeter team based at the Tremough campus in Cornwall has now proved that artificial lighting in towns and cities is modifying habitats for entire colonies of species – and experts believe the changes might not be good ones.

The study, published this week in the journal Biology Letters, shows that the balance of different species living together is being radically altered as a result of light pollution produced by street lamps and other man-made illumination.

Artificial lighting, which is believed to be increasing by six per cent a year globally, is already known to affect individual organisms, but this is the first time that its impact on whole communities has been investigated.

The Cornish study found that groups of invertebrates living near to artificial lights included more predators and scavengers.

Experts believe this could be bad news for certain species. Too much outdoor lighting might even have a knock-on effect on birds and mammals that rely on certain insects for food.

And when experts take this logic to its ultimate conclusion, they say we must question whether or not too much artificial lighting could be affecting entire ecosystems and even humans.

Members of the research team based their study in Helston, where they placed pitfall traps directly under and between street lamps for a number of days and nights.

This allowed them to compare not only results for day and night, but also differences between areas directly under street lights and the slightly darker places in between.

In all, the researchers collected 1,194 individual creatures from 60 species and discovered that total numbers were more abundant under street lights.

However, these larger numbers also contained a good deal more predatory and scavenging species, such as ground beetles and harvestmen. This remained the case during daylight hours, as well as at night, suggesting that the effect on communities is ongoing.

Lead author Dr Tom Davies, of the Environment and Sustainability Institute at the Tremough campus, said: "Our study shows that light pollution could be having a dramatic effect on wildlife in our towns and cities. We need to be aware of how the increase in artificial lighting is impacting on the delicate ecosystems on which we all rely.

"Our research shows, for the first time, the changes that light pollution is making to entire communities of invertebrates.

"We now need to examine what impact this is having on other communities and how this may be affecting important ecosystem services and whether we should change the way we light urban spaces."

http://www.thisiscornwall.co.uk/Street-lighting-dramatic-effect-wildlife/story-16183741-detail/story.html