Scientists have discovered thousands of new species living in a mineral-rich region of the Pacific deep sea that is poised to be extensively mined for resources in the coming years, posing a threat to these vibrant and largely unexplored ecosystems, reports a new study.
The Clarion-Clipperton Zone (CCZ), an underwater plain that spans 3,000 miles between Hawaii and Mexico, has become the world's largest mineral exploration region because it contains valuable metals such as copper, nickel, cobalt, iron, manganese, and rare earth elements. Located roughly three miles under the ocean surface, the CCZ is also one of the most pristine habitats in the global seas and is home to carnivorous sponges that look like light fixtures, spiny urchins, scaly worms, banana-like sea cucumbers, and countless creatures that are found nowhere else on Earth.
Prospectors have been interested in the CCZ since the 1960s, and a large chunk of the region has been claimed by companies for mineral exploration under the auspices of the International Seabed Authority, the intergovernmental body that regulates seabed mining. The zone’s growing reputation as a future mining hotspot has galvanized scientists to better understand the ecosystems that thrive in this remote habitat, which are largely unknown.
To that end, scientists led by Muriel Rabone, a deep-sea ecologist at the Natural History Museum in London, U.K., have now unveiled the first comprehensive checklist of “benthic metazoans” meaning seabed animals, in the CCZ, which was compiled from more than 100,000 records of expeditions to the seabed.
The researchers identified 5,578 different species in the checklist, of which 92 percent are new to science, which clearly demonstrates that “the CCZ represents significant undescribed biodiversity” and illustrates “the novelty of the region at deep taxonomic levels,” according to a study published on Thursday in Current Biology.
“Critical to the development of CCZ biodiversity knowledge is the creation of a curated checklist of known taxa and estimates of undescribed species,” Rabone and her colleagues said in the study. “Building on recent regional syntheses, we present the first comprehensive synthesis of benthic metazoan biodiversity and checklist for this vast region on the eve of possible large-scale mining operations.”
“We make these data and interpretations open to all stakeholders to inform the ongoing debate on deep-sea mineral extraction and to grow our knowledge of the largest ecosystem on our planet,” the researchers added.
Scientists have studied habitats in the CCZ for decades, but there’s been an explosion of knowledge about the region in recent years as a result of new techniques, including DNA sequencing, as well as deep-sea expeditions that have observed and sampled benthic wildlife. Rabone’s team built their new checklist from this deluge of new research, which revealed that the most common animals in the zone are arthropods, a group that includes crustaceans and shrimp, followed by worms, echinoderms (such as urchins), and sponges. While the new census provides our best glimpse yet of the region’s vibrant ecosystems, there are no doubt many other species in the CCZ that have evaded discovery so far.
“Many regions of the CCZ are almost unsampled and this data deficiency will contribute to underestimation of diversity for the region overall,” the team said. “Development in statistical methods for estimating species richness will be critical to future assessments of diversity in such poorly sampled environments. Given mining operations may be imminent, a key consideration for the CCZ is the application of biodiversity data for environmental management, in particular assessing species extinction risk.”
Scientists, policy makers, and other groups have warned for years that deep-sea mining might have devastating effects on ocean ecosystems, including those within the CCZ. Companies plan to deploy large vehicles in these regions that will grind down the seafloor to extract valuable minerals, which will destroy benthic habitats.
“The deep-sea environment is known to be highly sensitive to physical disturbance, and various tests of mining components and disturbance experiments have shown long-term influences of mining-like disturbances on the ecosystem,” according to a recent study in Marine Biodiversity. “In addition, depending on the type of machinery used, mining activities are likely to provoke the re-suspension of a large amount of sediment in the form of a sediment plume, which will spread out into the surrounding, unmined areas and may additionally harm organisms that were not mechanically affected by mining processes.”
In addition to these concerns, the sheer noise of mining operations could place new pressures on animals that inhabit these regions, many of which are already vulnerable due to other human-caused disruptions, such as climate change.
“Deep seabed mining operations, if permitted, could present significant risks to ocean ecosystems,” according to a recent study published in Frontiers in Marine Science that focused on marine mammals. “Disturbance on any scale is likely to be long lasting and irreversible.”
“Of particular concern is anthropogenic noise,” the study noted. “If permitted, commercial-scale mining is expected to operate 24-hours a day, at varying depths. The sounds produced from mining operations, including from remotely operated vehicles on the seafloor, overlap with the frequencies at which cetaceans communicate, which can cause auditory masking and behavior change in marine mammals.”
Rabone and her colleagues also emphasized the need to investigate the potential impacts of resource extraction on these mysterious habitats and to clarify the existing protections that are in place for them. For instance, the United Nations Convention on the Law of the Sea has declared that “no serious harm” can occur to the environment from any mining activities, though there is no set definition for this phrase, according to the study. The team called their new checklist “a starting point” that should be bolstered by future scientific exploration of the region.
“Accurately quantifying species ranges and rarity, key components of extinction risk, requires a comprehensive approach to taxonomy, extensive molecular studies, and standardized quantitative methods enabling regional analyses,” Rabone and her colleagues concluded. “This is particularly important given that the CCZ (together with the central-south Pacific and the Southern Ocean) remains one of the few remaining areas of the global ocean with high intactness of wilderness. Sound data and understanding are essential to shed light on this unique region and secure its future protection from human impacts.”