Embracing the Night I: Basics of natural darkness and light pollution

The Importance of Darkness for Wildlife and Ecosystems

Like humans, animals and wildlife also need protection from light pollution. Moonlight and predictable changes in brightness across lunar cycle influence many behaviours, including foraging decisions and reproduction abilities of nocturnal terrestrial and aquatic wildlife, navigation of wildlife such as migrating birds, the safety of wildlife and juvenile fish from predator species, and the ability of nocturnal pollinators and pest-controlling organisms to perform pollination and biodiversity health duties. Approximately 60% of insect species are nocturnal (Hölker, F., et al. 2010).

Research by Gaston et al. (2013) suggests that artificial light at night disrupts the natural circadian rhythms of organisms. It can shift their activity to earlier or later times, and in some cases, override their natural cycles entirely. This increases the daytime activity of some species while reducing the active time of nocturnal species, further disturbing the balance of ecosystems.

Light pollution disrupts ecosystems

Terrestrial ecosystems like forests and meadows play a vital role in attracting nature, culture, and wellness tourism. Activities such as berry-picking, observing wild plants and flowers, and staying in scenic landscapes highlight the cultural and natural value these ecosystems offer.  However, artificial light at night poses a growing threat to these ecosystems. Light pollution, depending on its colour and intensity, can draw pest-controlling and pollinating organisms away from their natural roles. This is especially concerning as pollinators are already in global decline, which has an effect on food production and wild plants.

In aquatic ecosystems, light intrusion can interfere with the physiological functions such as feeding and migration and increase exposure to predators. Young fish are particularly vulnerable to bright night-time lighting and reflections on the surface of the water. Light intrusion also contributes to eutrophication and the overgrowth of algae and aquatic plants, which can degrade water quality, harm aquatic life, and reduce the aesthetic and recreational value of water-based activities in tourism areas.

Like humans and animals, plants also need periods of darkness to regulate their biological rhythms. For example, deciduous trees typically flower or break bud in spring when it is warm and bright. Increase in the levels of light signals when to begin growth. Artificial lighting can confuse these signals, causing deciduous trees to retain green leaves too long in the autumn or bud too early in the spring. In autumn, as daylight shortens, trees stop producing chlorophyll, draw nutrients back into their roots, and shed their leaves. Bright lights during autumn rains or spring chills can disrupt this process. Repeated disturbances may weaken trees over time.