Deep-sea expedition finds new species

A deep-sea mining expedition in the Pacific Ocean has uncovered a large number of previously unknown species. This scientific campaign took place at several thousand meters below the surface, in the Clarion-Clipperton Zone between Mexico and Hawaii.

Growing interest in deep-sea mining

The growing interest in deep-sea mining, an activity whose actual impact is only beginning to be quantified, has prompted several countries to consider extracting critical metals from the ocean floor. This context led to one of the largest observation campaigns ever carried out in the Pacific abysses.

Research details and findings

The project, published in Nature Ecology and Evolution and conducted according to the guidelines of the International Seabed Authority (ISA), involved 160 days at sea and five years of work. Scientists collected 4,350 organisms measuring more than 0.3 mm and identified 788 species, mainly polychaete worms, crustaceans, and mollusks.

Biodiversity surprises

This number is surprising given that a deep-sea sediment sample typically contains about 200 specimens, but as many distinct species, demonstrating an unknown biodiversity. One of the few slightly more common species in the region is a small silky marine worm, studied by the team from the University of Gothenburg, measuring only 1 to 2 mm in length.

Mining impact assessed

The mining equipment trials leave visible traces in the sediments. The study reveals a 37% decrease in the number of animals and a 32% decrease in species diversity in their wake. These are significant impacts, but considered less severe than the most pessimistic scenarios predicted.

New species and biodiversity insights

According to biologist Thomas Dahlgren from the University of Gothenburg, most of the species discovered were completely new to science. DNA analyses proved crucial for understanding this biodiversity and anticipating potential losses linked to future industrial exploitation.

New coral species discovered

The researcher identified a new solitary coral attached to polymetallic nodules. The species was named Deltocyathus zoemetallicus. The researchers also observed that benthic communities naturally evolve over time, likely depending on the amount of organic matter reaching the seabed.

Biodiversity research continues

However, the exact extent of species distribution in the vast Pacific Ocean remains largely unknown. On Tuesday, June 20, Laurent Ballesta, Antonin Guilbert, Thibault Rauby, and Roberto Rinaldi resurfaced after 20 days of submersion at depths of more than 100 meters near the Cap Corse.

Focus on protected areas

According to Adrian Glover, lead author of the study and researcher at the Natural History Museum in London, the priority is now to better understand biodiversity in the 30% of the Clarion-Clipperton Zone that is under protection. "We know almost nothing about the fauna and flora in these areas. Assessing the risk of species loss before any decision on mining has become essential."