Ecologists have long studiedthe critical role of natural light in regulating species interactions, but, with limited exceptions, have not investigated the consequences of artificial night lighting. In the past century, the extent and intensity
of artificial night lighting has increased such that it has substantial effects on the biology and ecology of species in the wild. We distinguish "astronomical light pollution", which obscures the view of the night sky, from "ecological light pollution", which alters natural light regimes in terrestrial and aquatic ecosystem.
. In pre-industrial times, artificial light was generated by burning various materials, including wood, oil, and even dried fish. While these methods of lighting certainly influenced animal behavior and ecology locally, such effects were limited. The relatively recent invention and rapid prolif- eration of electric lights, however, have transformed the nighttime environment over substantial portions of the Earth's surface. Ecologists have not entirely ignored the potential dis- ruption of ecological systems by artificial night lighting. Several authors have written reviews of the potential effects on ecosystems or taxonomic groups, published in the "gray" literature (Health Council of the Netherlands 2000; Hill 1990), conference proceedings (Outen 2002; Schmiedel 2001), and journal articles (Frank 1988; Verheijen 1985; Salmon 2003). This review attempts to integrate the literature on the topic, and draws on a con? ference organized by the authors in 2002 titled Ecological Consequences of Artificial Night Lighting. We identify the roles that artificial night lighting plays in changing eco- In a nutshell: ? Ecological light pollution includes chronic or periodically increased illumination, unexpected changes in illumination, and direct glare ? Animals can experience increased orientation or disorienta- tion from additional illumination and are attracted to or repulsed by glare, which affects foraging, reproduction, commu? nication, and other critical behaviors ? Artificial light disrupts interspecific interactions evolved in natural patterns of light and dark, with serious implications for community ecology The Urban
WMands Group, PO Box 24020, Los Angeles, CA 90024-0020 (longcore@urbanvjildknds.or^ ? The Ecological Society of America logical interactions across taxa, as opposed to reviewing these effects by taxonomic group. We first discuss the scale and extent of ecological light pollution and its relation- ship to astronomical light pollution, as well as the mea- surement of light for ecological research. We then address the recorded and potential influences of artificial night lighting within the nested hierarchy of behavioral and population ecology, community ecology, and ecosystem ecology. While this hierarchy is somewhat artificial and certainly mutable, it illustrates the breadth of potential consequences of ecological light pollution. The important effects of light on the physiology of organisms (see Health Council of the Netherlands 2000) are not discussed