Deep-sea mining could imperil rare, ghostlike octopus | Science News for Students

Deep-sea mining could imperil rare, ghostlike octopus

Newly discovered octopus lays its eggs where miners are looking for valuable metals
Feb 3, 2017 — 7:10 am EST
Casper octopus

This ghostlike octopus was only recently discovered deep at the bottom of the ocean off an island near Hawaii. It makes its home at a site being eyed for deep-sea mining.

Courtesy of NOAA Office of Ocean Exploration and Research, Hohonu Moana 2016

Scientists released the first photos of a squishy, semi-transparent octopus last spring. Adults are about the size of an open human hand. Because of its haunting appearance, the scientists nicknamed it Casper, after the cartoon ghost. Now some researchers worry that these animals could soon disappear for real. That’s because these animals lay their eggs where companies are looking to mine valuable metals for use in electronics.

Autun Purser is a marine ecologist. As such, he studies the relationship of marine creatures to each other and their environments. Purser works at the Alfred Wegener Institute in Bremerhaven, Germany. In 2015, he and his team spent five weeks exploring the deep seafloor near where Casper had been photographed. This was in the South Pacific, off the coast of an island near Hawaii.

At this spot, rocky nodules litter the seafloor. They look a bit like potatoes. These nodules contain metals such as manganese, which are used to make electronics. And that interests mining companies, looking to supply electronics companies. If mining teams go after them, their activities might accidentally disrupt the environment that nurtures Casper and his kin.

"The nodules grow like pearls," explains Purser. "They usually start growing over a shark's tooth or a bit of broken shell. Slowly, over time, they form layers of rock.” These layers tend to include some of the metals now used in cell phones and computers.

While these metals can be found on land, rich deposits on land have already been mined. There is currently no deep-sea mining for these metals. But companies are considering it. "We thought we should try to understand what animals are in the area before we start mining," Purser now reports.

His research team sent a swimming robot down to the seafloor. This site was more than 4 kilometers (about 2.5 miles) below the surface. The robot towed a camera, which took pictures. Those photos turned up 29 octopuses from two different species. Two individuals were curled around their eggs. This egg protection behavior is known as brooding.

The octopuses had laid their eggs on the dead stalks of sea sponges. Those stalks resemble stiff blades of grass. Purser suspects the octomoms may guard their eggs like this for more than a year. That guess is based on work by other researchers who had monitored a similar octopus in shallower water. It had laid its eggs on the edge of an underwater cliff. The researchers sent down a camera every month to check on it. It took more than three years before its eggs hatched.

Story continues below image. 

To protect its young, an octopus wraps itself around its eggs on the stalk of a dead deep-sea sponge to protect its young (see inset). The sponge stalk is attached to a rocky nodule bearing metals used in electronics.
Autun Purser; Image courtesy of the Alfred Wegener Institute OFOS team 2015 

Unfortunately for Casper’s species, the sponges where it lays its eggs grow atop the rocky nodules that mining companies have begun eying. The octopuses also seemed to feed around the nodules and to hang out in seafloor structures, such as surface cracks and the metal-rich nodules.

Deep-sea mining for metals might one day take place across large sections of the seafloor. Powerful vacuums might suck up nodules and bring them to the surface. Or perhaps a system of dredgers or buckets attached to a conveyer belt would haul up the nodules. Either way, the process would likely wreak havoc on the seafloor ecosystem to which these octopuses belong.

The broad scale of mining being considered might one day "impact areas the size of small countries" — and do that every few years, says Daniel Jones. He is a marine biologist with the National Oceanography Centre, in Southampton, England. He has studied similar environments in the eastern Pacific, including areas with manganese nodules. It's important that biologists learn what’s living in these areas and the ecosystem impacts of mining, he says, so that companies can make wise decisions on where it's safest to mine metals.

Jones says Purser's work "is critical for enriching our understanding of this poorly-known deep-sea environment.” The octopus researchers, he adds, “are not only revealing important information for marine biology but also bringing to life an enchanting character in the complex story of life in the deep sea."

The Alfred Wegener team has some idea of what might be at stake. In the mid-1980s, other researchers from their institute pretended to mine the seafloor near Hawaii. They dragged a type of plow across roughly one square kilometer (0.4 square mile) of seafloor. This wiped it clear of nodules. Then they waited see how long it took for the seafloor to return to its pre-mined state.

Purser and his team are now investigating the differences between the plowed and unplowed sites. They have yet to analyze all of their data. But as far as they can tell, even after 30 years none of the nodules have returned. That means no sea sponges. And no sponge stalks on which Casper’s kin can lay their eggs.

If companies do mine the seafloor, Purser hopes they will do it in small patches. That should preserve large areas of nodules. "It would be nice to say don't do any mining,” he says, “but we all use mobile phones.”

Power Words

(more about Power Words)

behavior     The way a person or other organism acts towards others, or conducts itself.

biology     The study of living things. The scientists who study them are known as biologists.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the naked eye, it consists of watery fluid surrounded by a membrane or wall. Animals are made of anywhere from thousands to trillions of cells, depending on their size. Some organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

colleague     Someone who works with another; a co-worker or team member.

ecosystem     A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra.

electronics     Devices that are powered by electricity but whose properties are controlled by the semiconductors or other circuitry that channel or gate the movement of electric charges.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create for that organism or process. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.

manganese     The chemical element of atomic number 25, a hard gray metal of the transition series. Manganese is an important component of special steels.

marine     Having to do with the ocean world or environment.

marine biologist     A scientist who studies creatures that live in ocean water, from bacteria and shellfish to kelp and whales.

oceanography     (adj. oceanographic ) The branch of science that deals with the physical and biological properties and phenomena of the oceans. People who work in this field are known as oceanographers.

octopus     Sea mollusks with a soft, sac-shaped body and eight tentacles. Two rows of suckers along each tentacle give the animal an ability to grasp and hold onto things. Cousins of the squids, these animals have a sharp beak-like mouth and good vision.

Pacific     The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east.

robot     A machine that can sense its environment, process information and respond with specific actions. Some robots can act without any human input, while others are guided by a human.

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

semi     An adjective meaning “somewhat.”

species     A group of similar organisms capable of producing offspring that can survive and reproduce.

sponge     A primitive aquatic organism with a soft porous body.

transparent     Allowing light to pass through so that objects behind can be distinctly seen.


Journal: A. Purser et al. Association of deep-sea incirrate octopods with manganese crusts and nodule fields in the Pacific Ocean. Current Biology. Vol. 26, December 19, 2016, p. R1268. doi: 10.1016/j.cub.2016.10.052.