New species found thriving 13,123 feet below water surface during deep-sea mining test

Scientists involved in a new deep-sea research effort report that a recent mining test unexpectedly led to the discovery of large numbers of previously unknown species living 4,000 meters (13,123-feet) below the surface. Their findings indicate that the overall ecological impact of the mining activity was milder than many had feared. Even so, the team observed a clear decline in biodiversity, with species richness dropping by roughly one-third along the tracks left by the mining vehicle.

The work is part of a major international project in which marine biologists set out to document life on the largely uncharted deep-sea floor of the Pacific Ocean. According to the researchers, the discovery highlights how little is known about deep-ocean ecosystems and underscores the need for rigorous environmental assessments before large-scale mining is allowed to proceed.

Critical metals on seafloor need careful study According to Thomas Dahlgren, a marine biologist at the University of Gothenburg and one of the project’s lead researchers, the global push for a green transition is intensifying demand for critical metals that are currently in short supply. He explains that many of these metals exist in significant quantities on the deep-sea floor, yet there has been little clarity on how they could be responsibly extracted or what consequences such activity might have for the environment.

Dahlgren notes that this research project represents one of the first major steps toward understanding both the opportunities and risks associated with deep-sea resource exploration. Carried out under the International Seabed Authority’s (ISA) rules for baseline studies and environmental assessments, the project follows one of the most extensive examinations of deep-sea ecosystems to date.

Over five years, researchers catalogued marine life on the seabed and evaluated the effects of a mining trial in the Clarion-Clipperton Zone, a vast region stretching between Mexico and Hawaii. Their findings indicate clear ecological disruption: the number of animals dropped by 37 percent, and species diversity fell by 32 percent within the tracks left behind by the metal-collecting machine.

Data show surprising biodiversity in deep, low-nutrient waters The team’s survey of the seafloor 4,000 meters below the surface in a place with no sunlight and very few nutrients reveals how sparse life can be in the deep ocean. While a sample from the North Sea might hold around 20,000 individual animals, a similar sample from this depth contains the same number of species but only about 200 actual specimens.

During the project, researchers collected 4,350 animals larger than 0.3 millimeters from the seabed and identified 788 species in total. Most of the organisms were marine bristle worms, crustaceans, and mollusks such as snails and mussels. Now, after more than a decade of research in the region, the team has led the identification of marine polychaete worms. Because most of the species were previously unknown, molecular DNA data was essential for studying biodiversity and understanding the ecological dynamics of the seabed.

What matters now, the researchers say, is predicting the risk of biodiversity loss from deep-sea mining. This involves studying the 30 percent of the Clarion-Clipperton Zone that is currently protected, as very little is known about the species living in these areas.

Understanding the ecosystems in the protected zones will be crucial for assessing potential impacts and guiding responsible management of deep-sea resources.