The Effect of Light Pollution on Aquatic Life

With an ever-increasing pressure on our environment, the future of all living beings, including humans – who are the problem – is bleak. Through all the media that we know exist; water, air, soil, etc. our polluting activities pose an imminent threat to the flora and fauna around us.

India boasts a large coastline that abodes a plethora of aquatic species, whose existence is now endangered. It is not new that water pollution and soil pollution affects aquatic life. But there is another danger that is lurking around the corner; an invisible apex predator that poses harm to all marine life.

Today, the concept of artificial light is entirely taken for granted. Apartments, bungalows, resorts, clubs, skyscrapers and the like built near or along the shore produce immeasurable amounts of artificial light. This is especially so during the nights, when ornamental bulbs become incandescent and festoons glow for our entertainment, the lives of the neighbors residing in the waters is at potential risk.

This is due to a phenomenon called light pollution. To put it in simple words, the production of excessive light that alters nature’s conditions or activities causes light pollution. For millions of years, animals and plants have been adapted to the cycle of day and night. It is encoded in their DNA and they have been predictably surviving in this manner.  The advent of light-production has allowed us to use the power carelessly and nonchalantly, ignoring the massive impact it has been having on the environment for years.

Light pollution is a major problem for a simple reason – we cannot see the light. Unlike different forms of pollution, light-pollution is quite invisible, and yet it is inconspicuously killing India’s aquatic life. A single point-sized source of artificial light allows the light to spread unchecked over vast areas. Our deep-sea explorations too have carried this hazard to unfathomable depths and distances – considering the fact that the speed of light in water is a mind -bending 2250000000 meters per second!

The dangerous effect of light-pollution stunts the growth of several species of fish, and the routine behavior of nocturnal aquatic life has been negatively affected. As a result, the predator-prey relationship also changes, thus disrupting the natural order of events. Human-produced light eliminates the boundary between day and night, affecting aquatic life both physiologically and mentally.

For instance, in human beings, the hormone called melatonin is responsible for causing sleep. But light emitted from devices such as mobile phones, laptops, etc. reduces melatonin’s production, thereby disrupting our sleeping habits, or, in the worst cases even leading to insomnia. Similarly, in the case of fish, the artificial light hinder melatonin’s production, affecting their physiology and their daily cycle.


One species that has probably been the most impacted is the sea turtle. Sea turtles come to the shore to breed and nest, since they require a dark atmosphere (beaches). When the eggs hatch, the sea turtles use the reflective water’s surface as a guide to get back into the ocean. However, light pollution tends to confuse and disorient them. After roaming about on the shore, hundreds of sea turtles simply die in the absence of food, nourishment, etc. unaware that their home was just a meter away. As a result, places such as Goa that are known for their hospitable beaches that support sea turtles are witnessing a sharp decline in their numbers. Frogs too are active during the night, who croak for mating. Unnatural light largely affects their routine.

The major obstacle also includes the fact that there are no stringent laws and regulations in India recognizing the light-pollution’s adverse impact on our ecosystem. With lakhs of people living along the coast and carrying different commercial activities, large scale light-pollution can have a devastating impact on India’s aquatic life.

If you look up at the sky above, you will actually be able to count those scanty stars in the city, while the skies in rural areas are ubiquitously covered with visibly sparkling stars.

Such is the dreadful impact of light pollution on India’s aquatic life. The solution? People have to realize the repercussions of their actions, despite its magnitude. Who knows, switching on the torchlight in your mobile phone while at the beach could probably be leading an entire shoal of fish into a trap.

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