Environmental Management Considerations for Deep Seabed Mining


By Alison Swaddling, Deep Sea Minerals Environment Advisor, Secretariat of the Pacific Community.

As the world’s demand for metals and rare-earth minerals increases, the concept of obtaining these resources from the deep seabed is becoming a reality. In the Pacific, where some small island developing states have significant potential for deep seabed minerals, many governments see this new industry as a way of obtaining much-needed revenue.

The Deep Sea Minerals Project – a collaboration between the Secretariat of the Pacific Community (SPC) and the European Union (EU) – is assisting Pacific Island countries in their policy, legislation and regulatory developments with particular attention to the protection of the marine environment. To date, Cook Islands, Tonga, Fiji and Tuvalu have enacted legislation to govern deep seabed mining, and other interested Pacific Island governments are in the process of developing theirs as well.

It is of critical importance that the industry is managed effectively from a legal, social and environmental perspective.

While there are many positive benefits this industry can bring in the form of increased revenue, education and employment opportunities, economic development, advancements in science and technology, etc., it is of critical importance that the industry is managed effectively from a legal, social and environmental perspective.

Understanding the Deep Seabed Environment

The mineral deposits currently targeted for deep seabed mining, namely: seafloor massive sulphides, cobalt-rich crusts, and manganese nodules (other shallower mineral deposits, such as iron sands and phosphate nodules have some overlap, but are not discussed here), occur in vastly different environmental circumstances. Understanding these environments is the critical first step in determining if mining should proceed. There are organisations and academic institutions conducting research in these deep sea environments and significant advancement in this field has been spurred by mining companies conducting exploration for deep seabed minerals.

A key legal environmental component of deep seabed mining legislation is the requirement to conduct a prior environmental impact assessment for each proposed development. Although there can be some general environmental characterisations inferred for a particular mineral deposit type, a thorough individual environmental baseline, including physical, oceanographic, biological and existing activities assessment, is required. This baseline is not only needed to determine the potential environmental impacts and gain government approval, but will also be relied upon for effective monitoring of mining activities.

Potential Environmental Impacts

As we can make some general inferences about the environments of mineral deposits, there are also some general environmental impacts that are expected to occur, though their extent and severity will be site specific, depending on local conditions and the methodology of mineral extraction.

As with land-based extraction, the most immediate impact will be the physical removal of the minerals from their existing location. This affects the local biological communities by removing/disturbing the seafloor and the animals that directly inhabit the area. The process of removing the minerals from the seafloor will also create sediment plumes, likely to spread to areas outside of the direct mining footprint. This plume will smother the seafloor and the remaining biological communities, with decreasing severity from the mine site. The sediment plume may also affect deep pelagic species. In the case of seafloor massive sulphides and manganese nodules, the removal of hard substrate will have knock-on effects for the recruitment of animals, which require hard substrate to repopulate the area.

Fish and other mobile animals will potentially be attracted to the lights, noise and vibrations of the seafloor machines where they could be trapped in the machinery. However, the machine’s noise, light, vibrations, and the presence of a sediment plume may cause other animals to actively avoid the area.

It is likely that the immediate negative impacts of mining operations will be limited to the seafloor and the area just above it. Whilst the technology for the different extraction methods is still being developed, it is expected that the systems for lifting the material to the surface will be fully enclosed, thereby minimising impacts to the mid-water and upper-water column, and that any seawater that is recovered with the material will be treated and sent back down to the deep seafloor.

This returned seawater will itself create a water plume with slightly different characteristics to the surrounding seawater, such as turbidity, temperature, elevated dissolved metal concentrations, etc. It is highly unlikely that any proposal would gain government approval if the material recovery system is not fully enclosed, or the returned seawater discharge depth is at shallow water depths, where surface environments could be impacted.

In the Pacific, commercial exploration and academic marine scientific research is underway to study the impacts of deep seabed mining. The first deep seabed mining environmental impact assessment has been conducted by Nautilus Minerals, Inc. for a seafloor massive sulphide site in Papua New Guinea. The report and supporting studies are available at: www.cares.nautilusminerals.com/Downloads.aspx.

Management and Mitigation Measures

A major concern for this new industry is the potential for rare or endemic species to be lost. Whilst these species should be identified in the environmental impact assessment process, the establishment of set-asides (areas of similar seafloor habitats that are not to be commercially developed) can help mitigate species loss and maintain overall regional biodiversity.

The establishment of set-asides can help mitigate species loss and maintain overall regional biodiversity.

Another major concern is the potential conflict with tourism and fisheries industries. In many Pacific countries these industries are the largest contributors to national gross domestic product. Deep seabed mine sites, by their nature, will occur far offshore and their impacts are not expected to affect coastal tourism or fisheries. However, the location of the mine site will need to be considered in relation to migration routes, spawning sites, feeding grounds, and juvenile areas of fishes and also marine mammals. Separation of activities by depth and distance will be possible, as well as a probable management technique to be used by governments.

This is a new industry and new learnings and discoveries will be made along the way. It is, therefore, important to take a precautionary approach and incorporate adaptive management to ensure appropriate reactions to monitoring programmes and that up-to-date best environmental practice is adhered to.

The SPC-EU Deep Sea Minerals Project is working with Pacific Island countries to develop comprehensive deep seabed mining specific regulations that include such measures that are also harmonised across the region. With this new industry, it is important for countries to learn from each other and work together to ensure balance is reached between financial opportunity and environmental risk.

Additional information about seabed mining, impacts and environment management in the Pacific region can be found on the SPC-EU Deep Sea Minerals Project website: www.sopac.org/dsm.