Darkness is advancing in 20% of the oceans

United Kingdom, May 31 – Darkness is advancing across one-fifth of the world's oceans: over the past 20 years, the depth of the areas penetrated by sunlight and moonlight, essential for 90% of marine life, has shrunk by a total area of ??more than 75 million square kilometers.

This is demonstrated by satellite data analyzed by researchers at the University of Plymouth, United Kingdom, and published in the journal Global Change Biology.

The study reveals that between 2003 and 2022, 21% of the Earth's oceans darkened, both in coastal regions and in the open sea.

More than 9% of the oceans (a total area of ??more than 32 million square kilometers, similar in size to the African continent) have seen the depth of their illuminated area decrease by more than 50 meters, while 2.6% have seen a reduction of more than 100 meters.

The changes near the coast are likely due to increased rainfall and the influx of light-blocking sediments, nutrients, and organic matter from land into the sea.

However, in the open ocean, the phenomenon may be more closely related to variations in algal blooms and changes in sea surface temperatures.

The most notable variations in the depth of the illuminated zone in the open ocean were observed in the upper Gulf Stream and around the Arctic and Antarctic, areas of the planet strongly affected by climate change.

Darkening is also widespread in coastal regions and enclosed seas, such as the Baltic Sea.

These changes "reduce the ocean available to animals that depend on the sun and moon to survive and reproduce," explains ecologist Thomas Davies, lead author of the study.

"We too depend on the ocean and its light zones for the air we breathe, the fish we eat, our ability to combat climate change, and the overall health and well-being of the planet.

With all this in mind, our findings are cause for concern," it concludes. (Text and Photo: Cubasí)