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comment Daytime Light Pollution From Buildings May Harm Wildlife
Light pollution is usually defined as a problem of the night, when artificial lighting obscures our view of the stars and disorients migratory birds and other animals. A newly identified type of light pollution expands that definition to daytime, however, and may endanger the many animals that use water to find food and habitat or to orient themselves. Dark, glossy surfaces in the built environment—glass, asphalt, polished stone, photovoltaic panels, automobiles, and oil slicks, among others—all reflect polarized light, often more intensely than water, the chief natural source of polarized light in the environment.
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Many species are able to perceive polarized light, which occurs naturally when light is scattered in the atmosphere and when light reflects off water and other reflective surfaces, and such light provides important information about the environment. But man-made objects may polarize light more intensely than natural surfaces, offering “supernormal polarization signatures” that can be misleading. According to a recent article in the journal Frontiers in Ecology and the Environment, polarized light affects aquatic insects in particular but also water birds, turtles, reptiles, fish, crustaceans, and echinoderms. Reacting to polarized light from artificial sources, birds become disoriented and insects mate and lay eggs in inappropriate locations. Animals may fruitlessly seek to feed at parking lots full of shiny cars, and food webs can be altered when prey species are drawn in unusual concentrations to a polarized light source such as a glass curtainwall, where predators easily catch them and then themselves fall prey to other predators drawn to the easy feeding site.
Fortunately, even modest reductions in polarized light from artificial sources may prevent creatures sensitive to such light from being led astray, according to the article. The paper’s authors suggest reducing polarized light pollution by choosing building materials that are rough rather than smooth, and light rather than dark, and by minimizing outdoor lighting, especially near bodies of water.
Copyright 2009 by BuildingGreen, LLC
