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

Abstract

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.

Editorial: Biodiversity of the Clarion Clipperton Fracture Zone

“…It does seem to be clear, though, that nodules have both significant economic and ecological value (Fritz 2016). In particular, the removal or burial of nodules by mining activities will erase the biota that depend on nodules for habitat, and will also affect the soft-sediment fauna through sediment compression and disruption of near-surface sediment layers (Miljutin et al 2011;Vanreusel et al 2016;Jones et al 2017;Gollner et al 2017). Due to the slow growth rates of nodules (ca.…”

The Benthic Megafaunal Assemblages of the CCZ (Eastern Pacific) and an Approach to their Management in the Face of Threatened Anthropogenic Impacts

“…Several reviews (e.g., Smith, 1999;Sharma, 2015;Jones et al, 2017) concluded that there is a lack of information on the potential impact of sediment burial at the scale of the CCZ and that there would be considerable long-term negative effects on the ecosystem.…”

An Overview of Seabed Mining Including the Current State of Development, Environmental Impacts, and Knowledge Gaps

“…Mining for SMS at hydrothermal vents would involve mechanical removal of the ore and transportation to a support vessel to extract the necessary materials. Harvesting nodules would mean retrieving the potatosized deposits from the seafloor then pumping the collected material to a surface vessel through a vertical riser pipe (Blue Nodules, 2016;Jones et al, 2017).…”

“…Preliminary results and observations note that the original plow marks are still visible and there has been only a low level of recolonization, suggesting that disturbing nodules for commercial mining will cause longterm damage to the benthic ecosystem (JPI, 2016). A metaanalysis of 11 such test studies (including DISCOL) carried out by Jones et al (2017) reports that the effects of nodule mining are immediate and severe, and note that although signs of recovery were observed within 1 year following disturbance, at most sites, there was a significant reduction in the number of recolonizing species. Few species groups recovered to pre-mining baseline conditions even after two decades and Jones et al (2017) suggest that, even after smaller scale test mining experiments, the community-level effects of nodule mining are likely to be severe.…”