Biologists have discovered 5,578 different deep-sea species – of which an estimated 88 to 92 per cent are entirely new to science – in a huge region in the Pacific Ocean that is soon to become a mining hotspot.
The study identified a variety of previously unknown species in the Clarion-Clipperton Zone (CCZ), including a sea cucumber, a nematode, and a carnivorous sponge.
An area about twice the size of India – the CCZ – has already been divided up and assigned to companies for future deep-sea mining.
A team of biologists has built the first “CCZ checklist” by compiling all of the species records from previous research expeditions to the region and publishing their findings in Current Biology.
“We share this planet with all this amazing biodiversity, and we have a responsibility to understand it and protect it,” said Muriel Rabone, a deep-sea ecologist at the Natural History Museum London.
Spanning six million square kilometres from Hawaii to Mexico, the CCZ is one of the most pristine wilderness regions in the world's oceans.
To study it, researchers went to the Pacific Ocean on research cruises that used sampling techniques from the technical – such as remote-controlled vehicles on the ocean floor – to the simple, such as a sturdy box that lands on the bottom, called “box-core sampling”.
“It's a big boat but it feels tiny in the middle of the ocean," Ms Rabone said. "You could see storms rolling in; it's very dramatic.
“And it was amazing. In every single box-core sample, we would see new species.”
By studying more than 100,000 records of creatures found in the CCZ taken during these deep-sea expeditions, Ms Rabone and her co-authors found that only six of the new species found in the CCZ – which include a sea cucumber, a nematode, and a carnivorous sponge – have been seen in other regions.
They also found that the most common types of animals in the CCZ are arthropods (invertebrates with segmented joints), worms, echinoderms (spiny invertebrates such as sea urchins), and sponges.
“There's some just remarkable species down there," Ms Rabone said. "Some of the sponges look like classic bath sponges, and some look like vases. They’re just beautiful.
“One of my favourites is the glass sponges. They have these little spines and under the microscope, they look like tiny chandeliers or little sculptures.”
The team has stressed the importance of increasing cohesive, collaborative and multidisciplinary research in the CCZ to gain a deeper grasp of the region’s biodiversity.
They also underline the importance of learning more about the newly discovered species and how they are connected to the environment around them.
They urge researchers to delve into the biogeography of the region to better understand, for example, why certain species cluster in particular geological regions.
“There are so many wonderful species in the CCZ, and with the possibility of mining looming, it’s doubly important that we know more about these really understudied habitats,” Ms Rabone said.