Warming threatens life in ocean 'twilight zone'

The ocean’s ‘twilight zone’ – a crucial habitat for marine life – is under threat from global warming, according to scientists. The zone is found between depths of 200 and 1,000 meters, and its biodiversity evolved over millions of years in the cooler waters of the past.

However, the researchers’ study found that current warming trends could lead to a 40% reduction in life within the zone by the end of the century. The area, which is too dim for photosynthesis to occur, is a vital carbon sink and home to more fish than the rest of the ocean combined.

Scientists caution that climate change may drastically diminish life in the sunlit zones of the deepest parts of our oceans.

New research suggests that global warming may reduce life in the twilight zone by up to 40% by the century’s end.

Researchers discovered that the twilight zone, which ranges from 200m (656ft) to 1,000m (3,281ft), is filled with life but harbored fewer organisms in past warmer periods of the Earth’s history.

By examining records from preserved microscopic shells, scientists, led by the University of Exeter, analyzed two warm periods in Earth’s history – approximately 50 million years ago and 15 million years ago.

Less food reached the twilight zone from the surface during past warmer periods of the Earth’s history, as bacteria degraded it more rapidly, resulting in fewer organisms inhabiting the area, according to the researchers’ findings.

Dr. Katherine Crichton, the lead author of the study, stated that the diverse range of life in the twilight zone emerged in the past few million years as the ocean waters cooled and began acting as a fridge, preserving food for longer periods and creating better conditions for the thriving of life.

The disphotic zone, commonly referred to as the twilight zone, is a crucial habitat for marine life. Although too dim for photosynthesis, it is home to a greater number of fish than the rest of the ocean combined, as well as a diverse range of life, such as microbes, plankton, and jellies, as per the Woods Hole Oceanographic Institution.

The twilight zone also acts as a carbon sink by absorbing carbon from the atmosphere. Researchers simulated the impact of climate warming on the zone and found significant changes may already be occurring.

Dr. Crichton, the lead author of the study, stated that the research is the initial stage to determine the twilight zone’s vulnerability to climate warming.

Without a quick reduction in greenhouse gas emissions, she warns that the extinction of much of the twilight zone life could occur within 150 years, with long-lasting effects. The paper was released in the journal Nature Communications.



Source : bbc.com

By Ryan

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