New Deep-Sea Coral Found on Nodules Targeted for Mining
An international research team led by Dr. Guadalupe Bribiesca-Contreras from the National Oceanography Centre (NOC) and Senckenberg scientist Dr. Nadia Santodomingo have discovered a new species of deep-sea coral that lives attached to polymetallic nodules – the same mineral-rich rocks that are the focus of growing international interest for deep-seabed mining.
The coral, Deltocyathus zoemetallicus – now described in a new study published in the “Zoological Journal of the Linnean Society” – was found more than 4,000 meters below the surface in the Clarion–Clipperton Zone (CCZ) of the Pacific Ocean. This is the first known hard-coral species to live directly on these nodules.
The nodules grow extremely slowly – only a few millimeters over thousands of years. If mining were to remove them, this newly discovered species could lose its only known habitat – potentially before we fully understand its biology or ecological role.
The deep ocean floor was once thought to be flat, muddy, and largely lifeless, however it hosts a wide range of habitats and rich biodiversity.
The CCZ holds the world’s largest known deposits of polymetallic nodules – potato-sized lumps rich in manganese, nickel, cobalt, and other critical metals used in electric vehicle batteries and renewable energy technologies.
“This tiny coral is a hidden gem of the abyss,” says Dr. Nadia Santodomingo, the Head of Marine Invertebrates I Section at the Senckenberg Research Institute and Natural History Museum Frankfurt and one of the researchers behind the discovery. “It lives directly on the nodules that mining companies are preparing to extract. If these nodules are removed, we risk wiping out an entire species we have only just found.”
Unlike shallow-water corals that often host symbiotic algae, who in return provide nutrients for the coral via sun-dependent photosynthesis, Deltocyathus zoemetallicus survives in total darkness. This species is an azooxanthellate scleractinian, meaning it lacks an algal partner to provide nutrients, instead feeding on particles that are drifting through the water.
Using box corers during three expeditions onboard the OSV Maersk Launcher and one expedition on board the RRS James Cook, scientists carefully collected the new coral specimens and their nodule homes. The team then analyzed the animals using high-resolution imaging and 3D micro-CT scanning to confirm that it represents a species new to science.
Corals of the genus Deltocyathus are found in every ocean basin except the Arctic and around Antarctica. They typically inhabit depths between 200 and 1,000 meters, with the deepest known species recorded at 5,080 meters. Most Deltocyathus species are free-living, meaning they sit lightly atop the seafloor sediments, with the exception of the Atlantic species Deltocyathus halianthus and now Deltocyathus zoemetallicus which attach to hard substrates.
“This discovery underscores how little we know about life in the deep sea,” says Dr. Guadalupe Bribiesca-Contreras, lead author and Applied Scientist at NOC. “Every new species we find reminds us that the ocean floor is a living ecosystem and we still have so much research to do to explore and understand it fully.”