September 19, 2020

Light pollution, the dangerous light that threatens biodiversity



Disorientation, routine disorders, displacement to other habitats, mismatches in the food chain or mortality, are some of the negative effects that light pollution causes on fauna and that endanger the balance of ecosystems and the loss of biodiversity.

Experts consulted by EFE explain the effects and consequences of light pollution on animals and their behavior.

Light pollution “is like another pesticide in practice,” explained the astrophysicist in the Department of Sky Quality of the Institute of Astrophysics of Andalusia (IAA) and member of the Board of Directors of the International Dark Sky Association, Alejandro Sánchez de Miguel.

It is one of the most important factors of the so-called “insect apocalypse”, that is, the loss “in the last 25 years of around 75% of insects”.

Furthermore, from a “significant alteration” in the food chain as insects occupy an intermediate position, their attraction to the light of cities and towns causes other species to move out of their habitats.

This represents an “additional risk factor” for both animals and human health, since they can cause “agricultural pests or diseases,” says Sánchez de Miguel.

Living beings that have evolved have done so “under a regime of light and darkness” that has been disrupted with artificial lighting, Airam Rodríguez, a biologist at the Biological Station of Doñana, has pointed out. started studying around 2006. “

However, “there are many animals in the night habit that live with high light pollution and hardly perceive that it is night,” explained the head in the Zoology area of ​​the University of Valencia, Joaquín Baixeras.

However, the navigation and sensory systems, as well as the chronobiological rhythm of nocturnal species, are adapted to low light conditions, according to Baixeras, and the “most negative” effect of this contamination is “direct mortality”.

This is what happens with the Cinderella shearwater in the Canary Islands, specifically in Tenerife – between October 20 and November 10 – 2,800 chicks are rescued who fall dazzled, Rodríguez explained, despite the fact that “it is estimated that this amount only represents 60% of the copies “.

While sea turtle hatchlings become disoriented by the light and when they hatch from the egg on the beaches, they head towards land instead of the sea, and many “end up dehydrated, engulfed or run over,” according to Rodríguez.

Light pollution also causes the decline of fireflies, a species in which the function of light is emitted in search of a partner, and the excess of artificial light prevents them from meeting and blocks their communication system.

“The insects live very little time” and in that period they must “feed and reproduce”, with light they are “forced to divert their attention towards these foci,” explained Baixeras.

Nocturnal pollinators could see their colonies reduced, which would affect the pollination of plants and, with this, would decrease the amount of fruits and seeds available.

Rodríguez considers that this contamination does “a cleaning of genotypes” with “a cascading effect” that entails “a deterioration of biodiversity when species, individuals and the relationships that arise between the specimens are lost.”

Measures should be taken such as lighting “the essentials” to protect biodiversity, according to Baixeras, while Rodríguez is committed to systems with low-intensity and human sensors, and Sánchez de Miguel for turning off ornamental lighting.

They agree on the need to carry out “environmental impact reports” where biologists and environmentalists evaluate the impact of this type of pollution and its effects on the loss of biodiversity.

By Natalia Molina Iñigo

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