Biological responses to disturbance from simulated deep-sea polymetallic nodule mining

PLoS One. 2017 Feb 8;12(2):e0171750. doi: 10.1371/journal.pone.0171750. eCollection 2017.


Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities.

Publication types

  • Meta-Analysis

MeSH terms

  • Algorithms
  • Ecosystem*
  • Environment*
  • Mining*
  • Models, Theoretical
  • Oceans and Seas*

Grants and funding

The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under the MIDAS (Managing Impacts of Deep-seA reSource exploitation) project, grant agreement 603418. TR received funding from the Polish National Science Centre grant 2014/13/B/ST10/02996. Funding was also provided from the UK Natural Environment Research Council through National Capability funding to NOC. The funders had no role in the study data collection and analysis, decision to publish, or preparation of the manuscript.