Ocean life in deep-sea mining zone

  Expedition to the Pacific deep sea reveals Stunning images of creatures in mining zone  

An international team of scientists have spent the last few weeks on board a research boat exploring the eastern tropical Pacific Ocean. Their goal was to find out what is living 4,000 metres beneath the surface. Dr Adrian Glover was the Chief Scientist on the latest SMARTEX expedition, which is led by the National Oceanography Centre. In the abyssal Pacific there is a greater biomass of life in the top one centimetre of a given area of seafloor mud than in the entire 4,000 metres of water above it. This can seem surprising at first, given there is no sunlight at those extreme depths and the temperature is a frigid 1.5°C. But there is a relatively simple explanation, things denser than water such as dead algae, animals and their poop, sink. This is what we somewhat whimsically call “marine snow”. An endless dark snowfall forming the vast drifts of abyssal muds which characterise our planet. At some places in the middle of the Pacific Ocean geologists have measured the age of the deep sediment layers at 180 million years old. This means marine snow was falling in these parts of the ocean when Diplodocus was browsing on ferns and Ichthyosaurs were swimming the waters above. This is an extraordinarily long snowfall, and a reminder of just how old some of our ocean basins are.

The region of the Pacific is part of what is known as the Clarion-Clipperton Zone (CCZ), a vast region which covers the same area as most of the continent of Australia. This area contains a vast deposit of polymetallic nodules, which are potato-sized mineral accretions that are gaining attention for the role they might play in the transition to green technology. The early explorations of the CCZ were focussed on these nodules as a potential mineral resource, but this over-looked an astonishing level of life that thrives at these depths. A large amount of time and space, are clues to answering the paradox in deep sea biology of why are there so many deep-sea species. We can forgive the first collectors in the CCZ for ignoring all this life – on first glance a typical view of the seabed at 4000 metres looks completely barren. But as is always the case, when we look more closely we find things.

Tiny sponges and bryozoans just a few millimetres in size grow on the nodules. In the mud between the nodules, small crustaceans, worms and molluscs are surprisingly diverse. Drive across the seafloor in a robotically-controlled submarine and after some time, you find larger animals too. These wonders are just an initial snapshot of fantastic creatures discovered 1,640 miles (5,000 meters) beneath the surface of the Pacific Ocean in a pristine area which is earmarked as a site for deep-sea mining of critical and rare metals. The natural resources are in high demand for use in solar panels, electric car batteries and other green technologies, among other uses. The 45-day expedition to the Clarion-Clipperton Zone, which wrapped March 20, documented biodiversity in the abyssal plain. Using a remotely operated vehicle, the team on board the UK research ship James Cook photographed the deep-sea life and took samples for future study.

We have a selection of some of the astonishing life which was found during the latest SMARTEX expedition to the CCZ. Some of these animals have been slowly persisting in the depths of the Pacific Ocean for potentially hundreds of years, from the Barbie-piglet sea cucumber to intricate, beautiful glass sponges. 

A perfectly circular pink-hued sea anemone with a fring of tentacles bathed in the light from the rover.

An extraordinary sea anemone reaching out to catch any pieces of marine snow drifting down from the surface. 

A sea sponge growing on the ocean floor. It is a white stalk, with what looks almost like a white shuttlecock growing from the end. 

 

Some of the sponges growing in the CCZ are so unusual it looks almost as if the researchers are exploring another world.

 

A ghostly white, long, thing crustacean with lots of legs. 

An almost worm-like tanaid, which are a group of crustaceans that live on the sea floor. 

A orange sea anemone growing amongst the jagged grey manganese rocks on the ocean bottom. 

An abyssal sea anemone growing in a manganese-encrusted reef 4,100 metres beneath the surface. 

“We can assume that many of these species will be new to science. Sometimes they have been seen/observed/known before, but not collected or formally described,” said Regen Drennan, a postdoctoral marine biologist at London’s Natural History Museum. “These specimens will be brought to the NHM London to be identified and studied for years to come.” The voyage was the second conducted by a UK initiative known as the Seabed Mining and Resilience to Experimental Impact, or SMARTEX, project, involving the Natural History Museum, National Oceanography Centre, British Geological Survey and other institutions. Scientists believe many of the life-forms that call this environment home would be unlikely to recover from the removal of the nodules and are calling for protections, according to the Natural History Museum. Some 6,000 to 8,000 species could be waiting to be discovered in the Clarion-Clipperton Zone. In extreme ocean depths, there is no sunlight and the temperature is around 35 F (1.5 C), but life-forms such as this glass sponge thrive.

A large grey fish swimming just above the muddy ocean bottom. 

Despite the extreme pressure, there are a few vertebrates that can survive in the depths such as this rattail fish. 

A deep sea sea star with long, filament like arms curved around.  

Sea stars with whip-like limbs are frequently seen living on the abyssal plain. 

A tall, vase-like white glass sponge growing on the muddy bottom. 

A beautifully delicate glass sponge spends its life filtering out nutrients from the never-ending fall of marine snow. 

A yellow coral-like branching byozoan growing on a nodule.  

A large, branching bryozoan using one of the polymetallic nodules as a surface on which to grow. 

The arms of a star fish draping down over the central shaft of a sponge stalk. 

A brisingid sea star sitting on a sponge stalk to raise its arms into the water to catch falling food.

The pink amperima sea cucumber, nicknamed the “Barbie pig,” is one of the largest invertebrates living on the deep-sea floor. Along with the transparent unicumber, the creature is a type of sea pig within the scientific family called Elpidiidae.  "The Barbie pig grazes upon the small amounts of detritus that descend from surface waters to the seabed and are important in terms of cycling organic matter, explained Drennan, who wasn’t directly involved in the expedition. “Many species in this family have developed long stout legs that allow them to walk across the seafloor, and elongated mouthparts to pick and choose the detritus they feed on,” Drennan said.

The expedition also captured images of elegant, cup-shaped glass sponges, which are thought to have the longest life span of any creature on the planet — up to 15,000 years, although the expedition team doesn’t know how old the sponges they photographed are. Sea anemones, close relatives of jellyfish, “fill the role of large sit-and-wait carnivores on the deep sea floor, catching small swimming animals in their tentacles,” she added. Many of the life-forms that live in these depths are reliant on the polymetallic nodules, which form ever so gradually through chemical processes which cause metals to precipitate out of water around shell fragments and shark teeth, according to the Natural History Museum. Researchers estimate that it takes roughly 1 million years for these nodules to grow just tens of millimeters in size. The largest known nodules reach around 8 inches (20 centimeters) across, which suggests that these environments have remained virtually unchanged at the bottom of the ocean for tens of millions of years.  Critics say that noise could disrupt marine mammals such as whales and dolphins, while plumes of sediment, potentially containing toxic compounds, kicked up by equipment on the seabed may disperse, harming midwater ecosystems, according to recent research. It’s also possible, these scientists warn, that deep-sea mining could disrupt the way carbon is stored in the ocean, contributing to the climate crisis."

However, several countries, including the UK and France, have expressed caution, supporting a moratorium or ban on deep-sea mining to safeguard marine ecosystems and conserve biodiversity. Most of the species encountered on the seafloor are unknown to science, such as sea pig nicknamed the "Barbie-pig" due to its hot pink colour and tiny "feet".  The US Geological Survey estimates that 21.1 billion dry tons of polymetallic nodules exist in the Clarion-Clipperton Zone — containing more reserves of many critical metals than the world’s land-based reserves combined. If deep-sea mining follows the same trajectory as offshore oil production, more than one-third of these critical metals will come from deep-ocean mines by 2065, the federal agency estimated. In international waters, the Clarion-Clipperton Zone is beyond the jurisdiction of any one country. The International Seabed Authority, under the UN Convention on the Law of the Sea, has issued 17 exploration contracts.