CA - University of California, Los Angeles: Study identifies how much artificial light is too much for two coastal species
There’s less light pollution along Southern California beaches than in densely populated inland areas. But even lower levels of artificial light along the coast disrupt the normal biological behaviors of fish and birds native to the region.
The study, published in the Journal of Coastal Research, focused on the grunion and plover because of their importance to conservation: Both are sensitive to environmental stressors and both can indicate an ecosystem’s overall health.
Researchers used satellite images and ground-based measurements to build a detailed map of light pollution along a 0.9 mile-wide strip of coast stretching from about 6.2 miles north of the northern Ventura County line to 6.2 miles south of the southern Orange County line. They then combined the map with information from local citizen-scientists who track plover and grunion locations.
The scientists found that light pollution levels were the single most important factor in predicting where grunion would lay their eggs, and the second most important, after the width of the beach, for predicting where plovers would roost.
A UCLA-led study has quantified, for the first time, how much of that light is too much for the Western snowy plover, a small shorebird, and the California grunion, a fish. Grunion avoid breeding where there’s light pollution brighter than a full moon, and plover avoid roosting — or settling in groups for the night — in areas with more than a half-moon’s worth of artificial light, the researchers found.