4,139 Animals Found Inside 244 Polymetallic Nodules: Scientific Reports Study Calls Nodule Interiors a Distinct Deep-Sea Habitat
A new study published in Scientific Reports shows that polymetallic nodules in the deep Pacific are more than a source of metals. Their crevices and pores form a specialized habitat for tiny organisms, according to an international team led by Tanja Stratmann of MARUM at the University of Bremen, Coral Diaz-Recio Lorenzo and Sabine Gollner of NIOZ, the Royal Netherlands Institute for Sea Research.
Polymetallic nodules are fist-sized lumps of iron and manganese oxides that grow extremely slowly, often just a few millimeters per million years. At depths of 4,000 to 6,000 meters, they form rare hard surfaces on the otherwise soft, muddy seafloor.
Using box corers and diving robots in the Clarion-Clipperton Zone of the central Pacific, the team dissected nodules in the laboratory to extract organisms from the crevices. Analysis of 244 nodules revealed a total of 4,139 individual animals, an average of 17 per nodule, with as many as 245 in a single nodule.
The number of animals inside nodules is lower than in surrounding sediment, about 10 percent of the sediment total for nematodes and about 25 percent for small copepod crustaceans, the researchers said. But species composition differs, and genetic analyses showed communities inside nodules were very similar across distances of up to 1,000 kilometers while differing significantly from sediment animals.
The single-celled species Thurammina sp. 1 is particularly common in the nodules and appears adapted to their sheltered spaces, with no replacement habitat if nodules are removed, the study said.
Gollner said the findings point to a possible irreversible loss of undescribed and unique biodiversity associated with nodules from commercial mining, which needs to be considered in environmental management. The paper carries digital object identifier 10.1038/s41598-026-76737-w.
Published by GSM · USA (original Chinese edition)
Photo: 图：多金属（锰）结核标本的特写。Hannes Grobe 摄，CC BY-SA 4.0，经 Wikimedia Commons / Photo: Manganese-nodule-09 hg. By Hannes Grobe, CC BY-SA 4.0, via Wikimedia Commons
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