Deep Sea Mining – A new frontier for ecosystem destruction

Catherine Coumans Ph.D., Research Coordinator and Asia-Pacific regional program coordinator.

This week the United Nations’ International Seabed Authority (ISA) is meeting in Jamaica to consider draft regulations for the exploitation of seabed mineral resources. MiningWatch Canada joins a growing global outcry over the speed at which the ISA is moving from licensing deep sea exploration to adopting regulations for mining the deep sea.

MiningWatch joins scientists and concerned citizens in calling for the application of the precautionary principle in the form of a moratorium on ISA contracts for seabed mineral exploration, and on exploitation, until independent scientists have had a chance to fully understand the deep sea environment and provide advice on how it should be protected.

MiningWatch’s assessment of Canadian mining company Nautilus’s deep sea project in Papua New Guinea provides ample reason to support such a moratorium.

Once again, a Canadian mining company is leading the way in pioneering a highly dubious mining practice. And again the country of choice for this latest environmental experiment is Papua New Guinea (PNG). Canada’s Barrick Gold is using the 800 kilometre-long Strickland River system in PNG as a dumping ground for its unconfined mine waste (a practice that is not permitted in Canada), and Canada’s Placer Dome used the sea as a dumping site for its mine tailings by piping them into the ocean from its Misima Island mine (also not permitted in Canada). Perhaps for the industry it is a short step from dumping unconfined mine waste into the ocean, to actually mining the ocean floor. This is what Canada’s Nautilus Minerals Inc. (Nautilus) plans to do in the Bismarck Sea, some thirty kilometres off the coast of PNG between the islands of New Ireland and New Britain.

Nautilus’s Solwara 1 project aims to mine copper, gold, and silver at a depth of 1,600 metres from seafloor massive sulphide deposits (SMSs), as well as from sediments on the seafloor around and below these deposits.[1] Seafloor massive sulphide deposits are also known as hydrothermal vents, or “black smokers.” These hydrothermal vents thoroughly astounded the scientific community when they were discovered in 1977. They are formed when seawater penetrates deep under the seafloor through cracks and is subsequently heated to temperatures that may exceed 400 degrees Celsius, for example by a magma source. The heated water spouts back out of the sea floor carrying with it dissolved metals. As the water hits the seafloor surface and cools the metals are deposited in layers, creating over time the tall “chimneys” associated with hydrothermal vents. The concentration of metals in and around the hydrothermal vents is generally higher than in deposits on earth[2] making them a tempting target for mining.

What is at risk?

What particularly stunned the scientific community about hydrothermal vents was the discovery of abundant, divers and never before seen life forms in what was considered at the time to be an environment far too harsh to support life (pressures associated with up to 5000 metres depth, permanent darkness, extreme heat, and high acidity). Among the species found were microbes that derive energy from chemicals rather than from sunlight. These microbes form the basis for other life around the vents. According to marine specialists at the Woods Hole Institute:

No two vents discharge exactly the same mixes of fluids, so no two vents are colonized by exactly the same life forms. Researchers continue to find new vent species just about every time they look for more. (...) So little is known about them that if vents are mined, we may never know what species have been lost.[3]

Furthermore, marine experts readily admit that not only species unique to a particular mined vent will be lost, but biodiversity critical to ecosystem resilience as a whole is at risk: “The result could be the subsea equivalent of replacing an old-growth forest with a field of dandelions. (...) Too little research has been conducted to know for sure.”[4]

Lack of regulatory oversight

Very little is known about the deep sea environment - it is often commented that more humans have walked on the moon than have visited the sea at these great depths[5] and that we have more detailed maps of Mars than we have of the deep sea. Why then are mining companies such as Nautilus granted the opportunity to mine and destroy what has not yet been fully explored, with undetermined consequences for the marine environment, for associated terrestrial communities and natural systems, for human knowledge about the origins of life on earth and about potentially beneficial genetic resources? Part of the answer lies in the fact that within the territorial waters of a nation, where the Nautilus project is located, that country can issue permits for exploration and exploitation at will.

Outside territorial waters the International Seabed Authority (ISA), [6] established under the United Nations some five years after hydrothermal vents were discovered, has the authority to grant exploration contracts for the seabed. The ISA has been doing just that, granting 26 mineral exploration contracts, 18 of which in the last 4 years[7] even in the absence of regulations for deep sea mining in international waters. Approximately 1.5 million square kilometres of the seabed is already covered by exploration licences. Of the 26 mineral exploration contracts granted, 22 have entered into force, five of which are for polymetallic sulphides, or hydrothermal vents. [8]

This week the ISA is meeting in Jamaica to consider draft regulations for the exploitation of seabed mineral resources. The framework being considered at this point is only for the exploitation of polymetallic nodules. However, there is growing global concern over the speed at which the ISA is moving from licensing exploration of deep sea mineral resources to adopting regulations for mining the deep sea. Scientists and concerned citizens are calling for the application of the precautionary principle in the form of a moratorium on ISA contracts for seabed mineral exploration, and on exploitation, until independent scientists have had a chance to fully understand the deep sea environment and provide advice on how it should be protected.[9]

MiningWatch’s assessment of Nautilus’s Solwara 1 project provides ample reason to support a moratorium on deep sea mining.

Lack of appropriate technology for reliable deep sea environmental impact assessment and for mitigation of unintended or accidental impacts

In 2011, MiningWatch Canada joined with local partners in PNG and Australia to form the Deep Sea Mining Campaign (DSMC).[10] A critical focus of the campaign has been Nautilus’s Solwara 1 project. The DSMC has commissioned independent reviews of the Environmental Assessments for the Solwara 1 project. These reviews point to significant deficiencies, some of which are related to very real difficulties inherent in carrying out a credible environmental assessment for a deep sea project. For example, the Solwara 1 project consists of 11 hectares that will be mined, but the company acknowledges that its impact footprint will be larger, in part because sediments kicked up in the mining process will disperse through ocean currents.

The problem is that no one knows exactly how much larger the footprint will be due to a lack of reliable deep sea modelling of physical and biological forces that transport sediments. This point has been proven many times in the case of the dumping of mine tailings from terrestrial mines into the deep sea via a submerged pipe. In most known cases mine tailings have spread for more widely than predicted by consultants, and by modelling, prior to the operations.

Of particular concern in the Solwara 1 project is the disposal into the deep sea environment of waste effluent from initial processing on board a ship. This effluent is meant to spew out of a pipe about 25-50 metres above the seabed creating a waste plume that is expected to be carried outside the immediate impact zone of the mine. Lack of reliable modelling makes it impossible to pre-determine the ultimate horizontal and vertical reach of the plume with a high degree of accuracy.

Toxicity testing for the effluent that will be discharged into the deep sea environment shows that it is toxic to shallow water species typically used in such studies, and would need dilutions up to 700 times to lose toxicity to these species: “The undiluted elutriate waters prepared from the cold sediment, and crushed active and weathered chimney mineral samples were found to be toxic to both the algae and copepods.” (EIA 9.4) Nautilus’s consultants used shallow water species for this toxicity test because they recognized that it would be impossible to do the tests on the deep sea species that will actually be affected by this effluent as these will not withstand being brought to the surface for testing: “no tests using local species from Solwara 1 were available or practicable, animals living at Solwara 1 do not survive for very long under conditions found at the surface” (EIA 9.4).

Having done the toxicity tests on shallow water species the consultants subsequently dismissed the results of these tests as irrelevant as “species that exist at Solwara 1 have both differing exposure pathways (e.g., water versus food) and sensitivity to metals.” So while the consultants acknowledge unique characteristics of deep sea species on and around hydrothermal vents, they have failed to conduct toxicity testing on them.

Nonetheless, the toxicity testing on shallow water species is important in regard to possible shallow water discharges of the toxic waste products from on-board processing. Such shallow water discharges could occur, for example, through a leak or breakage of the pipe system that is meant to carry the waste effluent into the deep sea environment.

Surprisingly, while the EIS considers possible operational leaks of fuel and hydrocarbons at the sea surface, as well as possible spillage of a little ore as it is transferred from the processing ship to a barge, and even acknowledges that it will discharge sewage at surface levels, the EIS dismisses the possibility of discharge of the toxic process effluent at shallow or mid-water depths:

During operations at the MSV [the ship], the only discharge to surface waters will be the discharge of sewage, treated to meet MARPOL standards (see Section 9.9 for further detail). This may elevate nutrients locally and the resultant plankton productivity. Minor quantities of spills of ore may occur during transfer to and from barges. As discussed in Section 9.4, there will be no discharge of water from the dewatering process within the surface or mid-water (mesopelagic) depths in the ocean, therefore no thermal changes to these layers will occur. (EIS 9-14)

A long history of pipe breaks in the dumping of mine tailings into the deep sea, not to mention ongoing leaks, and breaks in mine waste pipe conveyance systems on land indicate that such leaks or breakages have to be expected, particularly in the dynamic marine environment. The important point here is that in a marine environment it is much more difficult, if not impossible, to mitigate the impacts of leaks or accidental discharges of, for example, toxic process effluent into shallow water.

The examples provided here explain why the upbeat conclusions drawn by Nautilus consultants about the expected lack of significant environmental impacts from the project, are too often based on best case scenarios, speculation and hopeful “expectations” rather than on hard data.

Desperate measures to justify deep sea mining

Based on scientific knowledge of hydrothermal vents, Solwara 1 will destroy biodiversity as it will likely destroy species that have not yet been discovered, even at the relatively better-studied Solwara 1 site, and that are endemic, unique, to the individual hydrothermal vents mined.[11] In a recent report commissioned by Nautilus the company appears to seek to divert attention from this reality by arguing that deep sea mining will be less damaging than terrestrial mining. To this end, Nautilus hired Earth Economics (EE) to compare the potential impact of the Solwara 1 project with terrestrial copper mines, two existing and one proposed. Earth Economics does not explain why it only ran its comparison on the copper component of the ore from the Solwara 1 site and not on the significant gold content that will be obtained by Nautilus.

The three copper mines chosen as comparison sites by EE are particularly nasty projects. We can only applaud the irony that a mining company has paid for a comprehensive review of very well-known, well-researched, and well-documented devastating social and environmental impacts associated with mining as it occurs all over the world. However, the confidence that EE displays that deep sea mining of hydrothermal vents will be less environmentally damaging remains unsupported. It is more factual to describe it as an expansion of environmental damage of a new and different kind, with as yet largely unknown impacts, in a previously un-mined environment.

Earth Economics relies for its analysis on studies paid for and supported by Nautilus, but does not critically assess these studies or address the kinds of concerns with the EIS that are raised above. Furthermore, EE appears willing to adopt the same unsupported optimism that other paid consultants display. For example, in regard to potential recovery of the mined out Solwara 1 site EE says that “[a]s Nautilus indicates (...) the mine site could recover quickly following disturbance, if adequate hard substrates and larval recruits are available.” In fact, independent scientists have long pointed to the slower than usual recovery of damaged deep sea ecosystems due to harsh conditions in the deep sea.[12] Even Nautilus’s EIS notes that “[i]t is thought that rates of colonisation and growth of organisms such as the bamboo coral Keratoisis on hard inactive substrates are slow (Van Dover, 2000a) and hence, recovery of Keratoisis and its associated fauna may take longer than recovery of active vent communities” (EIS 9-23). As discussion of recovery of the Solwara 1 mine site is based on hypothesis, it is at least as realistic to be pessimistic as to be optimistic.

The EE report relies heavily on an analysis of copper as facing steadily increasing demand, as essential to human development, and as decreasing in terms of economically viable deposits on earth. These premises set EE up to argue that recovery of the high grade deposits that Nautilus is seeking to mine is important for human development. Leaving aside the current collapse in demand and prices for copper, it must be understood that hydrothermal vents are not abundant, and hydrothermal vents that are economic to mine even less so. And while the metal grades in hydrothermal vents are higher than most metal grades on earth, it has been noted that the total metal content of hydrothermal vents is lower than that of ore deposits on land “[i]t is therefore unlikely that the marine mining of massive sulphides will have a significant impact on global resource supply.” In other words, terrestrial mining will continue unabated. In that case, the harm caused by terrestrial mining will only be supplemented by harm to the marine environment.

Finally, an obvious observation, which must nonetheless be made: changing operating environments from terrestrial to marine does not change the nature of the industry itself, which is responsible for often unnecessary harm in terrestrial mining. It is the very same industry that is associated with ongoing devastation at existing and planned mines around the world, devastation well described by EE, that is now seeking profits from the sea: the same industry, the same investors, the same funders, the same profit motives. It is simply not believable that just by changing ecosystems this beast will also change its spots.

[1] Other potential targets of future deep sea mining operations are polymetallic or manganese nodules, which are found at depths below 4000 metres and cobalt crusts on the sides of undersea mountains at depths of 1000-3000 metres.

[2] For example, copper concentrations in mineable deposits on land will be around 0.6 % while copper grades at the Solwara 1 site are around 7.2%. Canadian National Geographic. May 13, 2014.

[3] What is seafloor mining? Woods Hole Institute. Accessed July 2, 2015.

[4] Ibid.

[5] Twelve humans have walked on the moon. The greatest depth achieved by humans in submersibles is about 1100 metres. Only three humans have reached this depth.

[6] International Seabed Authority. See The ISA was established under the 1982 United Nations Convention on the Law of the Sea. 

[7] Center for Ocean Solutions. “Managing mining of the deep seabed: Contracts are being granted, but protections are lagging.” ScienceDaily, 9 July 2015. . For a list of the sites see

[8] Another 14 ISA licences are for exploration for polymetallic nodules, and 3 for exploration for cobalt crusts. See

[9] The meeting of the ISA in Jamaica to discuss regulations for deep sea mining is attracting a significant amount of attention. Avaaz has a petition calling for a moratorium at; see also The Center for Biological Diversity sent out the following media release: 

[10] See MiningWatch has served on the management committee of the DSM Campaign since its inception. The campaign is staffed by Dr. Helen Rosenbaum and Natalie Lowrey and is a Project of The Ocean Foundation, a Partner of Mission Blue/Sylvia Earle Alliance and a Member of the Deep Sea Conservation Coalition.

[11] Earth Economics notes that “High levels of genetic diversity amongst microorganisms have also been fund at the Solwara site, with few “dominant” species. Typical ranges for any given species are generally below one metre. Species only feet away from each other might have little or no relation or shared genetic material.” p.25.

[12] See for example Center for Ocean Solutions. “Managing mining of the deep seabed: Contracts are being granted, but protections are lagging.” ScienceDaily. 9 July 2015.