Deep Sea Mining and Ecosystem Adaptability

We know more about the surface of the Moon and about Mars than we do about [the deep sea floor], despite the fact that we have yet to extract a gram of food, a breath of oxygen or a drop of water from those bodies.                          – Dr. Paul Snelgrove, Oceanographer

Mining From Land to Sea

Since the beginning of civilization, the Earth’s surface has been exploited for its valuable resources (e.g., metals, coal, minerals, etc.) through the act of mining. These invasive operations cause a negative environmental impact by the physical destruction of habitats and chemical contamination, which ultimately contribute to the loss of biodiversity. With a dramatically increasing population and a projected world population reaching 9.8 billion in 20501, the subsequent need for these materials is also growing. However, with continually decling resources available on land, miners are searching for alternative locations where these resources are readily available, such as the ocean floor.

Sulfide, Cobalt, Manganese, Oh My!

The deep-sea is the lowest point in the ocean, with the deepest part reaching a depth 10,994 meters (36,070 feet). Since little is known about this environment, it is most often thought of as an ominous, cold, dark place that is devoid of life. Yet, it is teeming with diverse creatures and unique geologic structures that contain valuable mineral deposits (Figure 1). Three types of deep-sea mineral resources that are currently being approved for exploration include: sulfide on hydrothermal vents, cobalt on seamounts and manganese on the sea floor (Figure 2). In addition to containing valuable minerals, these locations are also home to unique ecosystems with animal communities that vary in diversity, population and composition. For example, sulfide deposits contain elements such as copper, lead, zinc, silver, gold, nickel. However, mussels, snails, shrimps, worms and crabs are among the organisms that are native to these sites. Cobalt is found in deep-sea crusts, which accumulate at a very slow pace (only 1-6 mm per million years!). Although the mining of these crusts can provide up to 20% of the global cobalt demand4, they are located in regions of the ocean that are home to many slow growing, long-lived marine species such as sharks and tuna. Lastly, manganese is found in slow growing bulbs (i.e. nodules) that accumulate at a rate of 10 to 20 mm per million years. Manganese is used for for many technological applications, such as disk drives, rechargeable batteries and fluorescent lamps. The nodules are also an important source of habitat for roundworms, isopods, jellyfish and octopuses (see featured image). Even though many resource planners believe that mining for these minerals is essential for continued industrial health and national security of the world, no commercial deep-sea mining has taken place. This is because (1) the technology to propel the deep-sea mining activities is limited and (2) the environmental and ecological impacts on these understudied ecosystems are completely unknown.

Figure 1: The distribution of mineral resources throughout the deep sea including sulfides, cobalt crusts and manganese nodules.2
Figure 2: Examples of deep-sea minerals. From left to right: sulfides, cobalt crusts and manganese nodules.3

To Mine or Not To Mine?

Increased demand for new technology, which utilizes sulfide, cobalt, and manganese has led to the development of a plan to open a deep sea mine. Yet, scientists are struggling to understand how organisms living in the deep sea will be affected. Dr. Sabine Gollner and colleagues recently published a scientific study highlighting the lack of knowledge that scientists have about deep-sea ecosystems and how they will respond to proposed mining activities. The authors conducted an analysis of published studies to gain a better understanding of the recovery of deep-sea communities after natural and human disturbances (e.g., volcanic eruptions and destructive fishing). The goal of this study was to analyze the potential for communities to adapt and bounce back to original conditions following these proposed mining activities.

The authors concluded that while some species could recover following mining events, overall, the amount of organisms that make up the various communities would decline for decades and possibly even centuries. Despite the authors’ best efforts to comprehend the ability of deep-sea communities to respond to mining disturbances, their final analysis was left with many unanswered questions. Overall, the ability of deep-sea communities to react and recover from mining is highly variable and continues to remain uncertain, especially since many of these organisms have yet to be identified. As a result, more research is required to gain a full understanding and appreciation for these deep-sea communities.

If deep-sea mining is pursued, the impacts may lead to changes in the deep-sea community that could have unexpected consequences. Although mineral extraction from these locations can be economically beneficial, Gollner and colleagues demonstrate that there is a need for more research on how deep-sea communities will overcome, behave and adapt to proposed mining activities.

Source: Gollner, S., Kaiser, S., Menzel, L., Jones, D.O., Brown, A., Mestre, N.C., Van Oevelen, D., Menot, L., Colaço, A., Canals, M. and Cuvelier, D., 2017. Resilience of benthic deep-sea fauna to mining activities. Marine Environmental Research. 

References:

  1. https://www.un.org/development/desa/en/news/population/world-population-prospects-2017.html
  2. Hannington, M., Petersen, S. and Krätschell, A., 2017. Subsea mining moves closer to shore. Nature Geoscience.
  3. http://www.jogmec.go.jp/english/stockpiling/metal_10_000002.html
  4. Ramirez-Llodra, E., Brandt, A., Danovaro, R., De Mol, B., Escobar, E., German, C. R., Levin, L., Martinez Arbizu, P., Menot, L., Buhl-Mortensen, P., Narayanaswamy, B., Smith, C., Tittensor, D., Tyler, P., Vanreusel, A., and Vecchione, M., 2010. Deep, diverse and definitely different: unique attributes of the world’s largest ecosystem. Biogeosciences 7, 2851-2899.
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Claudia Mazur

I am a Ph.D. student in the department of Earth & Environment at Boston University where I am a member of the Fulweiler Lab studying marine sediment biogeochemistry. Originally a geologist, I am interested in how living organisms interact with their nonliving environment to create biogeochemical processes that are necessary for life on Earth. When I am not in the lab or in the field, I enjoy cooking and exploring the vibrant city of Boston. Follow me and my adventures on Twitter: @cmazur_rocks

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