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You’re working on how street lights influence animals on the ground. Tell us more.
We know that aerial invertebrates, such as moths, are attracted to street lights and more can die as a result of flying into the lights, exhaustion or increased predation by other animals including bats. What we don’t know is if those casualties have a lasting impact on population numbers.

What did you find?
Because it is quite difficult to study the community composition of aerial invertebrates, we looked at ground-dwelling invertebrates, including beetles, spiders and ants, to see if their communities were affected by proximity to street lighting. We found indications that the lights are having a lasting impact on their distribution.

Are such effects on distribution damaging?
Damage is a bit of an extreme word. It constitutes a change to the environment, but whether that change matters needs to be investigated.

Broadly, how does such light affect animals?
In a variety of ways. We need to look at how artificial light affects things like the circadian rhythm of animals. Light helps regulate many seasonal and daily cycles – when you hibernate, when you come out of hibernation, when you mate, when you come out to hunt.

What about plants?
That is one thing we want to look at in more detail, in particular we are studying the impact of artificial lighting on plant phenology, that is, their flowering time, time of seed production, senescence in the autumn – the rate of colour change in leaves, leaf fall and so on. There is the potential for artificial light to affect these things.

Do concerns about upward light pollution detract from these issues?
It is a form of pollution we are only beginning to recognise, so anything that gets people talking about it is good – including aesthetic reasons such as sky glow that prevents you seeing the stars.

Why might a new generation of street lights be a worry?
Societies are beginning to experiment with new types of lighting, in particular whiter lighting. If, for example, having whiter street lights allows me to better pick out a pedestrian on the side of the road when I’m driving, then it may allow a ground beetle to pick out its prey against a complex background of colours. We need to know how such changes affect the ability of animals to carry out tasks.

What could we do if this proves to be harmful?
There is a range of strategies. One is switching the lights off, but I wouldn’t want to advocate that as there’s a big human element. We could also dim the lights and reduce the amount of light scattered into the environment.

Surely this is only going to get worse?
It seems that way. In our paper we quote a figure of a 6 per cent increase in artificial lighting per year globally. Developing nations will see most growth (Biology Letters, ).