Posted: 02.06.2023 17:22:00

Number of inhabitants of ocean’s ‘twilight zone’ may be reduced by 20-40 percent in the coming years

Climatologists from the UK have found that due to the increase in the activity of marine microbes, the number of inhabitants of the ‘twilight zone’ of the ocean in the coming years may decrease by 20-40 percent – as noted by the press service of the University of Exeter, TASS reports


The twilight zone is a layer of the World Ocean, which contains organic matter in the form of various microbes, animals and organic remains, descending to a depth of 200-1,000 metres from the upper layers of the hydrosphere. A unique ecosystem has developed there, adapted to life in the almost complete absence of light.

The researchers found that these ecosystems could become one of the biggest victims of climate change in the coming decades. Scientists came to this conclusion in the course of studying marine rock deposits that formed in the deep-sea regions of the oceans about 50 million and 15 million years ago.

The researchers compared the concentration of organic molecules and the typical number of shell and body impressions of the inhabitants of the ‘twilight zone’ in the rocks of these two time periods, as well as in deposits of colder eras.

It turned out that both 50 million years ago and 15 million years ago, the proportion of organic remains and traces of the existence of animals associated with the ‘twilight zone’ was less than in other eras. Scientists suggest that this is due to warming waters and an increase in the activity of marine microbes that decompose organic matter falling to the bottom. This simultaneously deprives the inhabitants of the depths of access to food and oxygen.

Climatologists have added this feature of the ‘twilight zone’ to the mathematical models of the modern climate and calculated how the state of this layer of the World Ocean will change in the near future. Their calculations showed that both the volume of falling food and the number of inhabitants of the ‘twilight zone’ will fall by 20-40 percent in the coming decades, and in one and a half to two centuries there will be no more than half of its inhabitants.

This will negatively affect the cycle of organic matter in the hydrosphere. Moreover, this will also affect the functioning of the ecosystems of the entire World Ocean as a whole and may provoke or further intensify the extinction of animals and plants that inhabit the hydrosphere.