The extraction of sand, gravel, oil and gas from seas has taken place for several decades, however recent discoveries of other rich mineral deposits on the seafloor, in addition to advancing technology, has generated an increased interest in deep sea mining.
As miners must remove nodules present along the seafloor to reveal minerals beneath them, the threat to the biodiversity at this level is a prevalent issue that needs to be addressed by the industry.
What is Deep Sea Mining?
The oceans of the world cover over 70% of the surface of planet Earth. At the deepest levels of the oceans, various useful materials exist including copper, diamonds, iron, cobalt, manganese and phosphorite deposits. As the aforementioned and other rare earth elements continue to deplete in their quantities around the world, looking to the oceans as new sources of these materials could change the mining industry completely1.
Sources of Deep Sea Minerals:
- Hydrothermal Vents: These vents arise within the Earth’s crust following the movement of tectonic plates that brings hot magma to the seafloor. As the ocean water is heated by the presence of the magma, various chemical reactions are initiated to eventually allow for useful metals such as iron, zinc, copper, lead and cobalt to be leached from surrounding rocks2.
- Polymetallic Nodules: Nodules containing precipitates of manganese, iron oxides, phosphorite, nickel, copper and cobalt are present at ocean depths of 4,000 - 6,5000 meters.
- Cobalt-rich Crusts: The precipitation of multiple layers of cobalt accumulate along the seafloor at a slow rate, approximately 800-2,500 meters below sea level.
- Polymetallic Sulphides
Extraction Methods for Deep Sea Mining
The highly specialized tools used by the mining industry during deep sea mining projects include dredgers, pumps, crawlers, drills, platforms, cutters and corers, many of which can perform autonomously in the harsh conditions of the deep ocean.
Additionally, certain minerals present on the seafloor often require more complex mining techniques that are specific to the mineral of interest. For example, the mining of polymetallic nodules often involves variants of the hydraulic suction system, which is a process that vacuums up the nodules from the seafloor to transfer the specific elements, such as manganese, directly to the mining vessel, subsequently releasing unused particles back to the ocean.
Additionally, the extraction of cobalt crusts can be damaging as a result of the complete removal of the top layer of the seafloor, a process that often removes a high amount of species dwelling in this area along with it3.
How Marine Life is Affected
Deep sea mining, regardless of the process utilized or the mineral being extracted, causes a major disturbance to the seafloor, thereby playing a significant role in harming marine life of affected areas.
While the mining industry is currently working towards developing more sensitive techniques that reduce the adverse effects associated with such extraction processes, the ability of ocean habitats to recover from such damage may be irreversible.
A recent study conducted by a group of researchers at the University of Gothenburg have investigated how such mining processes affect the sponge species Plenaster craigi.
Forming over the duration of several millions of years, Plenaster craigi is the most abundant sponge living on the seafloor at depths of up to 4,000 meters below sea level. The metazoan filter-feeding P. craigi sponges are often encrusted on the nodules that line the floor of oceans.
These sponges are more vulnerable to harm during mining processes that typically require the complete removal of the nodules upon which they reside. Additionally, as filter feeders, the P. craigi sponges take in nutrients by filtering through large amounts of water, which can therefore become contaminated as a result of the sand and mud that accumulates during active drilling of seafloors4.
The current declining nature of our ocean ecosystems has already shown irreversible effects on global health. While extensive deep sea mining exploration helps to improve the amount of minerals that are distributed worldwide, such processes pose a serious threat to marine life at this ocean depth that is already poorly understood.
The deep sea is currently only characterized by darkness, extreme pressure, cold temperatures and a high biodiversity composed of what is believed to be millions of species that have yet to be identified.
By interrupting the nature of this ecosystem, the risk of inducing irreversible damage involving habitat degradation, reduced habitat complexity, the introduction of toxic spills have innumerable potential impacts that could greatly affect the overall harmony of our oceans5.
Before any deep sea mining projects are initiated, there is an urgent need for the scientific community to identify the species that inhabit these depths of the oceans and further understand their resilience to disturbance, specific environment ecology and distribution.
Additionally, management corporations and governmental agencies must enforce strict regulations prohibiting such mining projects until all the necessary preliminary information is determined.
- “Seafloor Mining” – Woods Hole Oceanographic Institution
- “Hydrothermal Vents” – Woods Hole Oceanographic Institution
- “What is Deep-Seabed Mining?” – Deep Sea Conservation Coalition
- “A new genus and species of abyssal sponge commonly encrusting polymetallic nodules in the Clarion-Clipperton Zone, East Pacific Ocean” S. Lim, H. Wiklund, et al. Systematics and Biodiversity. (2017). DOI: 10.1080/14772000.2017.1358218.
- “Deep Sea Mining a New Ocean Threat” – Huffington Post