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Deep-sea species in the Clarion-Clipperton Zone

Photo: SMARTEX Project / Natural Environment Research Council / dpa

Deep in the sea between Hawaii and Mexico lies many a treasure. No gold coins or other valuable antiquities are meant, but raw materials such as manganese, cobalt and nickel. The deep sea in the middle of the Pacific Ocean, where the seabed is about 4000 to 6000 meters deep, is considered potentially the largest mining area in the world.

But what about oceanic life in the region? A research team has investigated this and discovered a surprisingly large variety. The scientists found an estimated 5580 animal species. More than 90 percent of these species are still undescribed, reports the team led by first author Muriel Rabone, a deep-sea ecologist at the Natural History Museum in London, in the journal Current Biology.

In an inventory of the so-called Clarion-Clipperton Zone in the eastern Pacific, the group had evaluated more than 100,000 data sets from seven sources about living organisms there.

Most of the species recorded are arthropods such as shrimps or crabs. But worms, echinoderms such as sea urchins and sponges are also represented. "There are remarkable species down there," says Rabone. "Some sponges look like classic bath sponges, others like vases. They're just beautiful.«

The Clarion-Clipperton Zone has an area of around six million square kilometres – roughly twice the area of India. The mineral resources there are important raw materials that are used to produce batteries for electric cars, for example.

The minerals may not be mined outside national territories. However, companies are allowed to explore such areas for mineral resources. The International Seabed Authority (ISA) has issued so-called exploration licences for one-sixth of the seabed of the Clarion-Clipperton Zone. Applications for commercial deep-sea mining will be reviewed by Isa this year.

"In view of the threat of mining, it is doubly important that we know more about these habitats, which have hardly been explored so far," says Rabone. In order to better understand the ecosystem, various expeditions have explored the Pacific Ocean in recent years. In doing so, they collected samples, some of them with remote-controlled underwater vehicles that travel across the seabed. Or simply with sturdy boxes that are pulled across the floor.

From such data sets, Rabone's research team has drawn up an initial inventory of the diversity of seafloor fauna in the Clarion-Clipperton zone. This checklist includes a total of 27 phyla, 49 classes, 163 orders, 501 families and 1119 genera. Except for the individual species, only 438 of the deep-sea inhabitants have been described so far. Many of them are likely to live exclusively in this region.

Although the new analysis expands knowledge of the fauna in this marine area, Rabone and her team point out that there are still many unexplored areas. The zone is rich in nodules and rocks, which distinguishes it from other deep-sea areas. There it could provide a habitat for a particularly large number of different marine animals. However, since there is hardly any data for these rocky areas in particular, the diversity in the region as a whole is still underestimated.

The Clarion-Clipperton Zone is one of the last areas of the global ocean with pristine wilderness. "We need to know what lives in these regions before we can understand how we can protect such ecosystems," says co-author Adrian Glover.

dpa/joe