Urban lighting makes it harder to see the stars. This makes it a concern to star gazers and amateur and professional astronomers. The International Dark-Sky Association tries to publicize the problem and promote solutions. The Italian Light Pollution Science and Technology Institute has another useful set of resource pages. Click here for the Institute's "World Atlas of the Artificial Night Sky Brightness."
But ecologists are also becoming concerned. Ben Harder points to some of the research in the story "Degraded Darkness" in the most recent issue of Conservation in Practice (a publication of the Society for Conservation Biology). Lots of species behave different in the light and the dark, or change their behavior when lights are on after dark.
"...Many of the effects of artificial light may resonate up and down food chains, dragging whole ecosystems into imbalance. And by modifying the playing field on which nocturnal organisms develop, interact, and reproduce, artificial light may sculpt not only their individual lives but also the biological evolution of their species...
It's tempting to assume that artificial light distresses only a few exquisitely sensitive species. But mounting evidence suggests that the disappearance of darkness can affect plants and animals in a variety of ecosystems. Snake populations are declining in the vicinity of developing parts of California, for example. And intriguingly, it seems that not all the blame lies with familiar culprits like new roads and neighborhoods. Nocturnal snake species are thinning out more rapidly than diurnal snake species, even in areas where development isn?t cutting directly into snake habitat. "There are certain areas in southern California," says biologist Robert Fisher of the U.S. Geological Survey, "that have what seems like suitable habitat for these nocturnal snakes. But they?re not there, even though their diurnal counterparts are." ...
Moore [a Wellesley College scientist - Ben] suspects that artificial illumination alters aquatic ecosystems from the smallest organisms on up. The implications are far reaching and could ultimately link light pollution to water quality. Minute zooplankton lurk well below the surface during the day to avoid predators, then rise to graze on algae at night. But artificial light discourages them from venturing toward the surface. "If their grazing is inhibited . . . effects will cascade up the food chain," Moore says. Algae populations could explode in response to reduced predation, and those blooms would deplete dissolved oxygen critical to fish, crowd out other photosyn-thesizers, and cast unwanted daytime shade on submerged aquatic vegetation that provides habitat for juvenile fish..."
An interesting article available on the web. (materials from a conference on the ecological impacts of artificial lighting can be found at the web page of the Urban Wildlands Group).
Ecology's systemic impacts and associated unanticipated consequences bring to mind the interactions between markets we study in economics. The Scientific American recently had a neat article on the impacts of reintroducing wolves into the Yellowstone National Park: "Lessons from the Wolf" Evidently, the reintroduction of wolves reduced elk populations, fewer elk browsed on willow trees, willow populations in stream bottoms rebounded, stream banks were stabilized, beaver populations grew by exploiting the willow for food and construction material, and trout habitat improved. Wolves outcompeted coyote populations, reducing coyote numbers and increasing the population sizes of coyote prey (voles, mice, etc.).