Deep Sea Mining


As companies move to find valuable resources in more hazardous territory – oil, gas, minerals – Dr Anjani Ganase asks us to pause and reflect on what mining the deep ocean means. As humans seek to exploit our most remote and unknown environments, we need to be mindful of the present threats brought about by decades of ecological damage from continuous production and consumption.

Why?
As long as we continue to build and advance our technology industry, there will always be a need to mine the elements used in our electronics. The iPhone, and most smart phones, on average are made up of over 75 elements and many have to been mined, including gold for electrical circuits, lithium for batteries, rare earth metals used to make up part of the screen and features in the phone.  However, it is not just phones, most modern electronics, battery systems and alternative energy systems, are built using these earth elements.

Over the last fifty years as our technology has advanced, this has come with a significant ecological price. Many of the elements mined are non-renewable, taken from a finite global supply. With limited recycling options and electronics needing to be replaced every three to four years, this means that the ecological impacts of mining will only get worse into the future. Mining for these elements takes place all around the world (China, Chile, US, Australia and Ghana), and with limited options for sourcing such elements, companies will continue to mine in countries with sub-standard environmental laws. As resources on land have already begun to be depleted, exploration for the minerals is expected to shift to the deep ocean. If environmental damage as result of mining is already difficult to manage within a country on land, it can be expected that the management of these deep ocean activities will likely be even more difficult.
 
Midwater animal biodiversity: Squid, fish, shrimp, copepods, medusa, filter-feeding jellies, and marine worms are among the midwater creatures that could be affected by deep sea mining. Photo sourced from Drazen et al (2020).
How?
Deep-sea mining basically consists of a deep-sea vehicle to scrape and dig the bottom of the ocean, either on submerged sea mounts (the tops of submerged mountains, 1 -3 km depth) or in the abyssal plains (the valleys between these submerged mountains, down to 6 km depth). The material that is dug will be pumped up to the surface, where water is removed leaving mined sediment, and all the waste products are discharged into the water column.

Environmental impacts

The areas that will be affected by deep-sea mining include the deep-sea bottom habitats, as well as the marine life that occupy the water column above (from the surface to 6 km depth). The area of impact consumes 90 % of the livable area for any deep ocean dweller.  Bear in mind that the deep sea is home to a large amount of marine life including organisms that grow along the seabed such as sponges, coral, worms and invertebrates, as well as plankton, fish and large marine mammals that occupy the water column. The environmental impacts range from the physical removal of these benthic ecosystems that have existed for hundreds of years without our even knowing what is there or understanding their ecosystem, to pollution of large areas of water

Many deep-sea dwellers are slow growing owing to the limitations of food and other resources at depth and are unlikely to recover from the physical damage of deep-sea mining. Scientists have already tested this out and showed that sites mined over 35 years ago showed no recovery. In the water column, loud mechanical sounds which are likely to travel much farther underwater, as well as the use of light above and in the water, can be disorienting for marine life, from the migrating whales to larvae of marine creatures that get transported on ocean currents, affecting organisms that might be feeding, finding mates, breeding and communicating. A most damaging activity is the dumping of sediment in the water column creating a sediment plume that will be released into the water column at multiple depths. It might be as if the densest plume of Sahara dust were to stay in our atmosphere. We would not be able to breathe.

The open ocean naturally has very little sediment, and life in the ocean is adapted to the clear water. Sediment can be transported with the current to smother bottom habitats large distances from the mining sites. Plumes in the water column can disorient marine life by altering light and sound conditions. The sediment particles can overwhelm larvae and filter feeders that are not use to having sediment settle on their gills and tentacles. For the microbial and planktonic community, sediment can stick and bombard them. Larger animals will also be affected as they feed on the animals that then feed on organic particulates. While this is only what can be conceptualized, the impacts in the larger area (owing to the transient nature of the open ocean) and over the long-term are unknown. So many deep-sea locations have not been explored that significant biodiversity can be lost without our ever having a chance to discover and understand them. Deep-sea mining will bring additional stress to fisheries, tourism industry, and exacerbate existing climate-related maladies being experienced by the ocean – algae blooms, dead zones and global warming and acidification.

What the future holds

As we continue to push for economic growth, the exploitation of natural resources will continue to destroy habitats and biodiversity. Currently most electronics that are disposed of every four years, are not recycled, which means that new resources will continue to be mined. New technology has been touted as the solution to fighting climate change, yet we are using the same level of unrestraint in our resource use to solve the primary problem of over consumption. We are causing climate change through our abusive consumption patterns: fossil fuels are not bad in themselves, what is bad is how wastefully we use them. We continue to use finite resources without consideration of the impacts to our global ecology.

The price to be paid to remedy our voracious consumption habits - to combat climate change - is very high. If technology is thought to be the solution to combat climate change, what is the solution for the severe environmental damage brought about by the tech industry and the pollution from the e-waste that now plagues many poor nations around the world? Maybe the solution is to re-evaluate what our economy means to us and make it more dependent on our wellbeing and resources managed for sustainable use. Let us actively strive to be a healthy economy where our lives and livelihoods are not valued in property or money, but rather on the quality of living. As it is now, we barely know what is in our deep-ocean backyard; how do we expect to mitigate the damage and impacts of deep-sea mining.
A schematic showing the potential impacts of deep-sea mining on marine ecosystems. Schematic not to scale. Sourced from Miller et al (2018).

References:
Drazen JC, Smith CR, Gjerde KM, et al. Opinion: Midwater ecosystems must be considered when evaluating environmental risks of deep-sea mining [published online ahead of print, 2020 Jul 8]. Proc Natl Acad Sci U S A. 2020;202011914. doi:10.1073/pnas.2011914117

Miller, K. A., Thompson, K. F., Johnston, P., & Santillo, D. (2018). An overview of seabed mining including the current state of development, environmental impacts, and knowledge gaps. Frontiers in Marine Science4, 418.




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