Wildlife & Biodiversity

Light pollution disrupts marine organisms’ hormonal cycles, reproduction: Study

Artificial light can easily wash out the glow of moonlight and starlight, which are important cues for marine organisms

By Arya Rohini
Published: Wednesday 13 September 2023
Photo: iStock
Photo: iStock Photo: iStock

Land-based life, including humans, fireflies and birds, is significantly impacted by artificial light at night.

However, a recent study by Cornell University, United States, argued that we should broaden our outlook to consider light pollution’s influence on coastal marine ecosystems, affecting everything from whales to fish, corals and plankton.

Marine organisms that evolved over millions of years to adapt to natural light now face an ever-increasing flood of light from anthropogenic sources along the coasts. 

Artificial light can easily wash out the glow of moonlight and starlight, which are important cues for marine organisms. 

This disrupts their hormonal cycles, inter-species behaviour and reproduction, noted the findings of the study published in the journal Aquatic Conservation: Marine and Freshwater Ecosystems on September 5, 2023.

The lead author of the research, Colleen Miller, cited an example explaining how artificial light impacts sea turtles. “Artificial light at night is harmful to sea turtles in two ways. Females trying to find a quiet, dark spot to lay their eggs avoid light and may end up not coming ashore at all,” Miller said in a press release.

Moreover, “hatchlings head toward inland lights instead of moonlight on the water and then die of dehydration or starvation”.

Furthermore, with the growing usage of LED lighting, the very nature of artificial light is also altering. Compared to prior technologies, LEDs often emit more short-wavelength light and can pierce deep into the water.

The experts, however, pointed out that the efforts to reduce the impact on migratory bids will also benefit marine species.

They suggested measures such as using as much red light as possible and putting up barriers to shield the coastline from artificial light. Red light doesn’t penetrate as far into the water.

“We also need to look at artificial light at night on a broader scale. We need much more data from a larger geographic area and over a broader range of organisms. We should be urgently concerned about how artificial light at night is affecting marine ecosystems,” said Miller. 

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