ACT Reading — Natural Science — Drill 3

NATURAL SCIENCE: This passage is adapted from the article "The Hidden Costs of Light: Ecological Disruption and Artificial Night" by Camille Roux (©2023, Environmental Biology Today). For most of human history, the biological world operated on a clear schedule: sunlight meant day, darkness meant night, and virtually every living organism calibrated its behavior accordingly. That schedule has been disrupted. Artificial light at night now reaches more than 80 percent of the world's surface, and researchers studying light pollution have found that this disruption extends far beyond the loss of visible stars. Insects are among the most dramatically affected organisms. Moths and other nocturnal insects navigate using the moon and stars as directional references, a strategy that worked reliably for hundreds of millions of years. Artificial lights override this navigation system, drawing insects toward sources that provide no food, no shelter, and no reproductive opportunity. Studies in agricultural regions have found that insect populations near artificial lights can be reduced by more than 50 percent compared to darker areas. Since insects occupy a foundational position in most terrestrial food chains—as pollinators, decomposers, and prey—these local depletions have cascading effects. Sea turtles offer a well-documented case of a different kind of disruption. Hatchlings emerging from beach nests use the brightness of the open horizon—historically the moonlit ocean—to navigate toward water. Coastal lighting has reversed this cue in many locations: nests near developed beaches produce hatchlings that move inland toward road lights rather than seaward. Conservation organizations have responded with lighting ordinances in nesting areas and the development of wavelength-specific lights that are less disruptive to turtle navigation. Migratory birds represent a third affected group. Many species migrate at night, navigating by stars and the Earth's magnetic field. Urban light pollution scatters and reflects off clouds and atmospheric particles to create a glow—called skyglow—that disorients birds and draws them into cities. Researchers tracking migrating birds have found that mortality rates are significantly higher in areas with intense skyglow, and that birds caught in urban light traps frequently collide with illuminated buildings. The common thread across these cases is a mismatch between an ancient biological signal system and an environment that has changed faster than evolution can compensate.