Light pollution at night disrupts ecosystem: Study

New York: Increased exposure to artificial or outdoor light, referred to as light pollution, at night not only raises health concerns for humans but can also significantly harm the entire ecosystem, says a new study. The study showed that light at night affects species' composition as well as their food chain length. "Night-time light is having profound impacts that extend to the entire ecosystem," said Mazeika Sullivan, Associate Professor from the Ohio State University in the US.

Artificial light is a pollutant, changing the natural course of life for people, animals and plants. "We are experiencing this pollution that we do not think about, but it is all around us and it is chronic and it is happening everywhere. It is also unprecedented in earth's history," Sullivan added. For the study, the team examined the effect of existing artificial light in streams and they manipulated the light in wetlands.

From those areas, they collected a variety of water-dwelling and land-dwelling invertebrate species, including mayflies, water bugs, ants and spiders. Findings, published in the journal of Ecological Applications, demonstrated that species composition changed with an increase in light intensity. They also discovered that the food chain length of the invertebrate communities shortened with more light, indicating that the ecosystem is less complex.

"Decreases in food chain length are a pretty big deal as it reflects not just changes in the architecture of an ecosystem, the numbers of various species but also shifts in ecosystem stability and nutrient flows," said Sullivan. In addition, invertebrates became less reliant on food sources that originate in the water when they were exposed to moderate light levels, results showed. Interventions such as carefully directing light, using motion sensors to activate lights only when they are needed and dimming them when human activity is minimal could all have the potential to lessen the effects of lighting near wildlife, the study noted.