We have been using electricity as a source of light for over a century, and with a rapidly expanding human population the amount of light pollution at night is increasing every year.
Artificial light at night is often-overlooked, but is a potentially very ecologically damaging consequence of human activity. In urban areas, the bright, orange glow caused by night lighting affects many species.
At night, natural lighting intensities are typically below 0.1lx, however, with over 7.4 million streetlights in the UK alone, this value is
much higher in urban areas. This artificial light at night has the potential to severely disrupt ecosystems, by altering the behaviour of keystone species. Recent research published in Applied Animal Behaviour Science from Cripes member Rhidian Thomas and co-authors showed just this, where invasive signal crayfish (Pacifastacus leniusculus) were shown to
drastically alter their behaviour in the presence of a streetlight. Crayfish reduced their activity, engaged in fewer interspecific interactions and spent more time in shelters when exposed to levels of street lighting recommended in the UK. In some ways, this may benefit ecosystems invaded by this species, by reducing their damaging foraging and digging behaviours, but it highlights how artificial lighting influences aquatic species.
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