Numerous valuable minerals, including nickel, cobalt, copper and manganese, are found at the bottom of the deep sea in the Clarion-Clipperton Zone (CCZ) in the Pacific. Deep-sea mining could soon begin in this area - possibly permanently destroying unique ecosystems. A study now shows that over 5,000 species occur in the region, most of which have not yet been scientifically described and have not yet been discovered in any other region. The results provide a basis for better assessing possible environmental impacts of deep-sea mining.
The Clarion-Clipperton Zone is an area of approximately six million square kilometers in the Pacific Ocean that stretches between Hawaii, Mexico and Oceania. So far, this deep-sea area is one of the last largely untouched regions of the world's oceans. But that could change soon. Because the seabed is rich in so-called manganese nodules. These are accumulations of minerals, including in particular nickel, cobalt and copper in addition to manganese. Because the area is in international waters, it falls under the jurisdiction of the International Seabed Authority (ISA). This has already issued licenses, which initially allowed the exploration of the raw material reserves and will also regulate the mining rights in the future. The first dismantling pilot tests took place in 2021. Without further regulations from the ISA, commercial mining could start as early as this year.
Inventory of biological diversity
However, scientists and environmental organizations warn that deep-sea mining could cause lasting damage to ecosystems on the sea floor. "A basic knowledge of the biodiversity in this region is essential for effectively managing the environmental impact of potential deep-sea mining activities, but until recently this knowledge was almost entirely lacking," explains a research team led by Muriel Rabone of the Natural History Museum in London. Although there have been several research expeditions to the Clarion-Clipperton Zone, the results so far have only provided information on small sections of the area and did not form an overall picture.
Rabone and her team have now for the first time compiled and standardized the research results available to date. "We created a CCZ checklist, an inventory of the biological diversity of marine organisms on the deep sea floor," they report. “This can be crucial for future environmental impact assessments. Based on the collected research results, the researchers estimate that at least 5,578 different species live on the sea floor of the Clarion-Clipperton Zone. Only 438 of them have been scientifically described and named so far.
Only eight percent known species
"So an estimated 92 percent of the species identified in the CCZ are new to science," the research team writes. Only six species have been spotted in other regions, including a sea cucumber, a nematode and a carnivorous sponge. Around one in four of the species is an arthropod, and almost one in five is an annelid. There are also many roundworms, echinoderms and sponges. “There are some remarkable species down there. Some of the sponges look like classic bath sponges, others like vases,” says Rabone. "We share this planet with all this amazing biodiversity, and we have a responsibility to understand and protect it."
From the perspective of the researchers, the study can form a basis when it comes to recording biodiversity in more detail in the future. “Our study provides the first regional estimates of species diversity for all size classes. While these estimates are subject to large uncertainties, they provide a starting point that can be further developed as additional data and approaches become available,” they write. "With mining potentially imminent, the application of biodiversity data for environmental management, particularly assessment of species extinction risk, is an important consideration for the CCZ." It is therefore important to collect additional data on ranges and species rarity. "Reliable data and insights are essential to shed light on this unique region and ensure its future protection from human impact."
Source: Muriel Rabone (Natural History Museum, London, UK) et al., Current Biology, doi: 10.1016/j.cub.2023.04.052