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[ASAP] Causal Approach to Determining the Environmental Risks of Seabed Mining

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

Jones, Daniel O. B.; Kaiser, Stefanie; Sweetman, Andrew K.; Smith, Craig R.; Menot, Lenaick; Vink, Annemiek; Trueblood, Dwight; Greinert, Jens; Billett, David S. M.; Arbizu, Pedro Martinez; Radziejewska, Teresa; Singh, Ravail; Ingole, Baban; Stratmann, Tanja; Simon-Lledo, Erik; Durden, Jennifer M.; Clark, Malcolm R.

PLoS One (2017), 12 (2), e0171750/1-e0171750/26CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)

Com.-scale mining for polymetallic nodules could have a major impact on the deepsea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first com. test mining for polymetallic nodules was carried out in 1970. Since then a no. of small-scale com. 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-anal. techniques. We find that impacts are often severe immediately after mining, with major neg. changes in d. and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less neg. 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 d. 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 neg. biol. effects of seafloor nodule mining, even at the small scale of test mining expts., 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 detg. 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.