Artificial light can change the patterns of ocean creatures. Photo: Umut Sedef // Unsplash
Amidst the vast expanse of our moonlit seas, Artificial light illuminates the night and penetrates the surface, causing turbulence to unfold beneath the shimmering waves. While the plastics and oils that permeate the oceans may be the first thing that comes to mind when one thinks of pollution, environmental scientists and biologists are delving into the effects of another long-recognized form of pollution: light.
A team of researchers from England, Norway and Israel has drawn up a map The first global atlas of light pollution of the oceans at nightDetermination of underwater light levels for coastal regions around the world.
To identify the strongest sources of light infiltration, leading oceanographer and marine biochemist Tim Smith of Plymouth Marine Laboratory used a methodology that included combining 2016 Atlas of night sky brightness With twenty years of ocean and atmospheric data records. the The data treasure trove included shipboard measurements of artificial light and monthly satellite data spanning from 1998 to 2017, which helps estimate light-scattering phytoplankton and sediment prevalence. Complex computer simulations have also been used to shed light on how different wavelengths of light travel at depth.
One set of data focuses on nocturnal light pollution, while the other set focuses on ocean color, which reveals the optical properties of water. With their model, the scientists predicted how artificial light would creep in from above the surface and penetrate the depths below. By measuring underwater levels of light, the study provides a glimpse into the potential biological response of marine species to this illumination.
Smith emphasized the critical importance of these light levels to biological organisms. To date, the true extent of its impact on marine ecosystems has remained largely unexplored and understudied.
From offshore oil complexes to residential coastlines, the glow from human development has the potential to penetrate the deep sea, transforming the behaviors and survival of the species that live there. Since photosensitivity varies across species, the research team sharpened one of the smallest species, in order to assess the impact on the food chain. Copepods, small planktonic crustaceans, spend their evenings near the ocean’s surface, using the sun and winter moon to navigate the depths during the day, where they hide from predators.
This graph shows the artificial light at night (ALAN), and sky brightness from the Global Atlas of (a) the Persian Gulf and (b) the North Sea, two of the most polluted ALAN regions on the globe (Table 2). The effect in water for ALAN is shown as the critical depth (zc) Tagged (c) the Persian Gulf and (d) the North Sea.
The team found that the effect of artificial light within the top meter of seawater is strong enough to trigger a biological response across nearly two million square kilometers of ocean, an area nearly three times the size of Texas. However, light penetration does not depend solely on the intensity above the water’s surface; The optical properties of water also play a role, and can vary seasonally. For example, in areas with exceptionally clear waters, such as parts of the South China Sea near Malaysia, artificial light at night can It penetrates depths of more than 40 metres.
The most intrusive forms of light pollution occur in areas where offshore oil and gas platforms, coastal development, and wind farms are located. Moreover, the shift toward energy-efficient light-emitting diode (LED) lighting, which urban planners have advocated, may inadvertently pose challenges for marine ecosystems, experts warn. Once the warm amber hues of sodium vapor lights, urban landscapes now emit a stark, piercing blue glow, accompanied by a broader spectrum of light that holds the potential to affect marine species.
The study is a nod to the scientists that they should focus future studies of the effects of artificial light on marine life. The study specifically highlights areas where ecosystems are particularly stressed by artificial light, which can lead to rapid evolutionary changes and adaptation, Smith said in a statement to NASA. Which is definitely something we need to pursue.
Editor’s note: Avery Schuyler Nunn is a writer, photographer, surfer, and science journalist based in California.
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