A vast area under the Pacific Ocean earmarked for controversial deep-sea mineral mining is home to thousands of species unknown to science and more complex than previously understood, according to several new studies.
Miners are watching an abyssal plain that stretches between Hawaii and Mexico, known as the Clarion-Clipperton Zone (CCZ), for rock-like “nodules” scattered on the sea floor that contain minerals used in clean energy technologies such as electric car batteries.
The lightless depths of the ocean were once considered an underwater desert, but as interest in mining grew scientists explored the region exploring its biodiversity, with most of the data in the last decade coming from commercially funded expeditions.
And as they looked they found more, from a giant sea cucumber called a “gummy squirrel” and a shrimp with a set of elongated bristly legs, to many different small worms, crustaceans and mollusks living in the mud.
That has fueled concerns about controversial deep-sea mining proposals, with the International Seabed Authority on Friday agreeing to a two-year roadmap for adopting deep-sea mining regulations, despite conservationists’ calls for a moratorium.
The Abyssal plain more than three kilometers under water covers more than half of the planet, but we know very little about it.
They are the “last frontier”, said marine biologist Erik Simon-Lledo, who led the research published on Monday in the journal Nature Ecology and Evolution who mapped the distribution of animals in the CCZ and found a more complex set of communities than previously thought.
“Every time we do a new dive we find something new,” said Simon-Lledo, of Britain’s National Oceanography Centre.
Campaigners say this biodiversity is the real treasure of the deep sea and warn that mining poses a major threat by creating huge swaths of undisturbed sediment.
The knots themselves are also a unique habitat for special creatures.
“With science as it is today, there is no situation where we would support seabed mining,” said Sophie Benbow of the NGO Fauna and Flora.
‘Greatness of mind’
The Clarion-Clipperton zone has the same age and size to appreciate the unique animals discovered there, scientists say.
The region is “mind-boggling”, says Adrian Glover, of Britain’s Natural History Museum, a co-author of the study with Simon-Lledo and of the first complete stock of species in the region published in Current Biology in May.
That study found that more than 90 percent of the species recorded in the CCZ—about 5,000 species—are new to science.
The region, which was considered essentially barren before the exploration boom in the 1970s, is now thought to have a slightly higher diversity than the Indian Ocean, Glover said.
He said that sediment sampling devices from the region can only get 20 specimens at a time-compared to maybe 20,000 for a similar sample in the Antarctic-but that in the CCZ you have to go much further to find the same creature twice.
Scientists are now also able to use autonomous underwater vehicles to survey the ocean floor.
This is what helped Simon-Lledo and his colleagues to find that corals and brittlestars are common in the shallow eastern regions of the CCZ, but almost absent in the deeper areas, where you can see a lot of sea cucumbers, glass sponges and soft-bodied anemones.
He said any future mining regulations would have to take into account that the spread of animals across the area was “more complicated than we thought”.
The nodules likely began as a piece of hard surface—a shark tooth or fish ear bone—that settled on the sea floor and slowly grew by attracting minerals that occur naturally in the water in extremely low concentrations, Glover said.
Each was probably millions of years in the making.
The area is “food poor”, meaning that less dead organisms are washed down to become part of the mud on the sea floor. Glover said that parts of the CCZ add only one centimeter of sediment every thousand years.
Unlike the North Sea, which was formed from the last ice age that ended 20,000 years ago, the CCZ is ancient.
“The abyssal plain of the Pacific Ocean has been like that for tens of millions of years – a cold dark abyssal plain with a low rate of sedimentation and life there,” Glover said.
Because of this, the environment affected by any mining is unlikely to recover in human hours.
“You’re basically writing off that ecosystem for maybe centuries, maybe thousands of years, because the recovery rate is so slow,” says Michael Norton, Director of the Environment Program, the European Academies’ Science Advisory Council.
“It’s hard to argue that that’s not serious damage.”
Erik Simon-Lledó, Carbonate compensation depth drives abyssal biogeography in the northeastern Pacific, Ecology and Evolution in Nature (2023). DOI: 10.1038/s41559-023-02122-9. www.nature.com/articles/s41559-023-02122-9
© 2023 AFP
Citation: Deep ocean targeted for mining is rich in unknown life (2023, July 24) retrieved on 25 July 2023 from https://phys.org/news/2023-07-deep-ocean-rich-unknown-life.html
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