9 August 2016
An area targeted for deep sea mining is teeming with diverse life forms, including several new species, a new study has found.
Countries have been eyeing the deep seafloor of the Clarion-Clipperton Zone (CCZ) — a massive 6 million square kilometers (~2.3 million square miles) area in the Pacific Ocean — for its “polymetallic nodules”, ball-like clumps rich in metals like cobalt, copper, manganese and nickel. But life forms lurking in the dark, deep seafloor of this zone remain largely unknown.
Now, a team of researchers surveying parts of the eastern CCZ leased to the UK Seabed Resources Ltd (UK-1) is beginning to unravel some of the region’s mysteries.
During their first survey in 2013, the team discovered that the region is jam-packed with megafauna (animals over 0.79 inches in size), according to the new study published in Scientific Reports. Using a Remotely Operated Vehicle (ROV), the researchers identified more than 6,000 individuals belonging to over 170 tentative species, including corals, sponges, colorful sea cucumbers and shrimps, in a small part of their study site.
Many of these species are rare or new to science, the team found. For example, the ROV collected 12 species during this preliminary survey, seven of which are new to science, researchers say, while four species may even belong to new genera.
Craig Smith, the project’s lead investigator and oceanography professor at the University of Hawai’i at Manoa School of Ocean and Earth Science and Technology (SOEST), estimates that overall, the study site is likely home to more than 1,000 species, 90 percent of which may be new to science.
“The area we studied in the eastern CCZ was more diverse than many other deep-sea areas such as the Atlantic abyss and canyons off the Hawaiian Islands,” co-author Diva Amon, a post-doctoral researcher at UHM SOEST, told Mongabay. “It was also more diverse than several Antarctic fjords.”
The study’s preliminary results also found that the marine animals at their study site seem to be concentrated around the polymetallic nodules. This is because the nodules provide large areas of hard surfaces for animals like corals or sponges to attach themselves to, Amon explained. “In fact, we found during our study that over half of all the species observed rely on the nodules as structures to fasten to,” she said. “These animals are also sessile, which means that once they settle, they cannot move.”
This association with the nodules suggests that mining could be disastrous for the deep-sea marine species.
“It is thought thus far that a combine-harvester-like machine will be used to remove the nodules likely resulting in local extinctions of the many animals, especially those that are sessile (corals, sponges, bryozoans, polychaetes, nematodes etc.) and call these nodules home, leaving no possibility for their re-establishment in the future,” Amon added.
“These machines will disturb and compact large swathes of sediment, kicking up sediment plumes, which will travel for kilometers before depositing elsewhere. Further entombment of the seafloor will occur when tailings are discharged into the water column. Not to mention other possible impacts that include light and noise pollution from machinery, and major changes to the geochemistry of the sediment, food webs and carbon sequestration pathways. The cumulative impacts of these operations aren’t yet understood but will likely be long-standing and ocean-wide.”
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