Last spring, researchers discovered what appeared to be a new species of octopod, crawling along the seafloor at a record-breaking depth of more than 4,000 metres off Necker Island, near Hawaii. Its colourless and squishy appearance immediately inspired the nickname "Casper."
Now, a report published in Current Biology reveals that these deep-sea octopods lay their eggs on the dead stalks of sponges attached to seafloor nodules rich in the metals used in cell phones and computers.
"Presumably, the female octopod then broods these eggs, probably for as long as it takes until they hatch--which may be a number of years," said Autun Purser of the Alfred Wegener Institute's Helmholtz Centre for Polar and Marine Research in Germany.
"The brooding observation is important as these sponges only grow in some areas on small, hard nodules or rocky crusts of interest to mining companies because of the metal they contain. The removal of these nodules may therefore put the life cycle of these octopods at risk."
Purser explained that the manganese nodules form similarly to pearls in an oyster. In a process that could take millions of years, metals gradually build up in rocky layers onto a small starting seed, perhaps a shell fragment or a shark's tooth.
"They are interesting to companies as many of the metals contained are 'high-tech' metals, useful in producing mobile phones and other modern computing equipment, and most of the land sources of these metals have already been found and are becoming more expensive to buy," said Purser.
He added that little was known about the creatures found in the deep-sea environments where those metals are found. In a series of cruises, the researchers set out to find the organisms that live there and to understand how the ecosystem and animals might be impacted by mining activities.
Their studies showed that octopods are numerous in manganese crust areas, precisely where miners hoped to extract the metals of interest. This puts these captivating octopods, which live their long lives at a slow pace, at particular risk.
Purser said, "As long-lived creatures, recovery will take a long time and may not be possible if all the hard seafloor is removed. This would be a great loss to biodiversity in the deep sea and may also have important knock on effects. Octopods are sizable creatures, which eat a lot of other smaller creatures, so if the octopods are removed, the other populations will change in difficult to predict ways."