Deep-sea mining could destroy the cradle of life on earth

As Papua New Guinea prepares to give the go-ahead to Canadian mining company Nautilus Minerals to dredge its coastal seabed for minerals, critics say environmental assessments have been inadequate, local objections ignored and new species of life could be extinct before they have even been discovered.

 

Nautilus mining tenements off the coast of PNG

Some scientists believe deep-sea hydrothermal vents systems may be where life first evolved on earth – but it was perhaps only a matter of time before mining the deep seas took off.

The idea of digging up the seabed one mile beneath the ocean surface to extract mineral-rich deposits such as copper and zinc first emerged in the 1960s. An initial flurry of interest in the 1970s was put off by low metal prices and UN regulations that exist on exploiting resources in international waters.

But with rising demand from China and India for rare earth metals like copper, and deep-sea surveys having now found concentrations of minerals four to five times those on land, it has returned but this time in the ‘unregulated’ territorial waters of PNG, conveniently close to the Asian markets.

Ecologists say the PNG government is allowing Nautilus to go ahead with the first ever commercial deep-sea mining project without properly considering the environmental impacts or local opposition. Nautilus investors include the mining giant Anglo-American which is ignoring indigenous opposition to a gold and copper mine in Alaska.

CRADLE OF LIFE ON EARTH
As well as being metal-rich, the volcanogenic hydrothermal deposits which Nautilus plans to mine are home to a unique ecosystem that is still largely unknown to scientists since being discovered in the late 1970s.

Initially, the deep sea was thought to be full of soft sediment and little else but the discovery of hydrothermal vents on the seabed, which produce the deposits, revealed a completely novel ecosystem, unreliant on photosynthesis.

‘It’s the cradle of life on earth,’ explains Dr Rod Fujita from the Environmental Defense Fund and author of studies looking into deep-sea mining, ‘and the only one that does not depend on sunlight. There are species there that are found nowhere else on earth. It’s not like any land habitats we are used to; in fact you have to have your perspective altered to appreciate this deep-sea world,’ he says.

The mining process in PNG will take the top 20-30m off the seabed at a depth of 1,500m and lift it up to the surface before transferring it by barge to processing sites on land.

‘You will destroy fauna just by lifting the land,’ says deep-sea ecologist Professor Paul Tyler, from the National Oceanography Centre at Southampton University. ‘It is possible you might mine at a distance [from the hydrothermal vents] but by mining close by you will affect the flow and the vents might switch off and then all the animals die – you lose a huge biomass.’

‘FLIMSY’ ENVIRONMENTAL REPORT
Nautilus has attempted to fend off these criticisms by publishing an environment assessment, co-produced by a respected deep-sea biologist Dr Cindy Van Dover. In it they admit the impact to vents and seafloor habitats will ‘inevitably be severe at the site scale’ and that they will take ‘many years’ to recover.

However, other ecologists say the assessment is ‘flimsy’ and fails to give a full account of the potential damage mining will cause.

Professor Richard Steiner, from the University of Alaska cites the incompleteness of classification of species found at the sites and an inadequate assessment of the risks associated with sediment and waste rock disposal. He also cites the effects of increased light and noise in the deep ocean environment and the toxicity of the dewatering plume [the process of removing water from the mined deposits] to deep-sea organisms, which will not be able to differentiate between food and junk sediment.

Of particular concern are the hundreds of thousands of tonnes of waste that will be produced by the mining process, which Steiner compares to that of a ‘giant underwater tractor’ and which will be pumped onto deeper seabeds nearby. Dr Fujita said the physics of water as well as weather and currents made it difficult to predict or contain any spill and that deep-sea mining had the capacity to produce pollution that could travel across into international waters.

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