Assessing Environmental Risks from Deep-Sea Mining

The deep seabed hosts mineral resources of increasing interest to an emergent deep-sea mining industry due, in part, to technological advances and limited terrestrial supplies.  Much of these resources are in areas beyond national jurisdiction (the Area) and subject to regulation by the International Seabed Authority.  The ISA is also tasked with protecting the flora and fauna of the marine environment.  Little is known about the impacts of deep-sea mining due to the infancy of the industry, the extremely large spatial scales that will be affected (as much as 10,000’s km2), and long temporal scales under which many deep-sea processes occur (some on the order of millions of years).  In data-deficient areas such as the deep sea, environmental risk assessments can be used to prioritize environmental management objectives using expert opinion and literature review.  Dr. Travis W. Washburn, Ph.D. candidate Phillip J. Turner, and Dr. Cindy L. Van Dover performed a literature review to compile a compendium of risks associated with deep-sea mining for an expert survey as well as to assess the amount of studies examining this problem in the past.  A scale, intensity, and consequence analysis was used to rank the vulnerability of different deep-sea habitats (e.g., nodule beds, active vents, and cobalt crusts) to various risks associated with deep-sea mining (e.g., habitat removal, increased light/sound, plume toxicity, etc.).  Habitat alteration was expected to have the largest impacts on the deep-sea environment, followed by a plume generated during mining, and plumes formed from returning processed material.  Habitat alteration may impact the entire community while sediment plumes were expected to impact single or multiple trophic levels.  Expert perception was that nodule mining will impact 10,000’s km2 and take millions of years to recover.  Risks associated with increased light, the masking of light or bioluminescence, and electromagnetic radiation were expected to be minor.  Certainty for all risks other than habitat alteration were low, illustrating the lack of information on deep-sea mining impacts even among experts and the need for future study.