Restoration experiments in polymetallic nodule areas
Gollner, Sabine; Haeckel, Matthias; Janssen, Felix; Lefaible, Nene; Molari, Massimiliano; Papadopoulou, Stavroula; Reichart, Gert Jan; Trabucho Alexandre, João; Vink, Annemiek; Vanreusel, Ann
(2022) Integrated Environmental Assessment and Management, volume 18, issue 3, pp. 682 - 696
(Article)
Abstract
Deep-seabed polymetallic nodule mining can have multiple adverse effects on benthic communities, such as permanent loss of habitat by removal of nodules and habitat modification of sediments. One tool to manage biodiversity risks is the mitigation hierarchy, including avoidance, minimization of impacts, rehabilitation and/or restoration, and offset. We initiated long-term
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restoration experiments at sites in polymetallic nodule exploration contract areas in the Clarion-Clipperton Zone that were (i) cleared of nodules by a preprototype mining vehicle, (ii) disturbed by dredge or sledge, (iii) undisturbed, and (iv) naturally devoid of nodules. To accommodate for habitat loss, we deployed >2000 artificial ceramic nodules to study the possible effect of substrate provision on the recovery of biota and its impact on sediment biogeochemistry. Seventy-five nodules were recovered after eight weeks and had not been colonized by any sessile epifauna. All other nodules will remain on the seafloor for several years before recovery. Furthermore, to account for habitat modification of the top sediment layer, sediment in an epibenthic sledge track was loosened by a metal rake to test the feasibility of sediment decompaction to facilitate soft-sediment recovery. Analyses of granulometry and nutrients one month after sediment decompaction revealed that sand fractions are proportionally lower within the decompacted samples, whereas total organic carbon values are higher. Considering the slow natural recovery rates of deep-sea communities, these experiments represent the beginning of a ~30-year study during which we expect to gain insights into the nature and timing of the development of hard-substrate communities and the influence of nodules on the recovery of disturbed sediment communities. Results will help us understand adverse long-term effects of nodule removal, providing an evidence base for setting criteria for the definition of “serious harm” to the environment. Furthermore, accompanying research is needed to define a robust ecosystem baseline in order to effectively identify restoration success. Integr Environ Assess Manag 2022;18:682–696.
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Keywords: Artificial nodules, Deep sea, Minerals, Mining, Mitigation, Geography, Planning and Development, General Environmental Science
ISSN: 1551-3793
Publisher: SETAC Press
Note: Funding Information: We thank Henko de Stigter, Tanja Stratmann, and Coral Diaz Recio Lorenzo, the captain and crews of RV SONNE and MV ISLAND PRIDE, and teams of the ROVs KIEL 6000 and HD14 for deploying frames with artificial nodules during the expeditions SO268 with RV SONNE and IP21 with MV ISLAND PRIDE, and Reyhaneh Roohi and Rianna Vlierboom for help in mounting nodules on frames on shore. We thank Anita van Leeuwen‐Tolboom for mounting and running the powders for XRD. Our thanks also go to the BGR for providing natural nodules and deep‐sea clay, and for their cooperation throughout the development of this project. We also thank GSR for their flexibility with regard to artificial nodule placement in their exploration contract area. Ship time was provided by BMBF (SO268) and by BGR (IP21). The work was financially supported through the JPI Oceans project MiningImpact “Environmental Impacts and Risks of Deep‐Sea Mining” August 2018 to February 2022 (NWO‐ALW grant 856.18.001 to S. G.; BMBF grant no. 03F0812A‐H to M. H., F. J., M. M., A. V.). Funding Information: We thank Henko de Stigter, Tanja Stratmann, and Coral Diaz Recio Lorenzo, the captain and crews of RV SONNE and MV ISLAND PRIDE, and teams of the ROVs KIEL 6000 and HD14 for deploying frames with artificial nodules during the expeditions SO268 with RV SONNE and IP21 with MV ISLAND PRIDE, and Reyhaneh Roohi and Rianna Vlierboom for help in mounting nodules on frames on shore. We thank Anita van Leeuwen-Tolboom for mounting and running the powders for XRD. Our thanks also go to the BGR for providing natural nodules and deep-sea clay, and for their cooperation throughout the development of this project. We also thank GSR for their flexibility with regard to artificial nodule placement in their exploration contract area. Ship time was provided by BMBF (SO268) and by BGR (IP21). The work was financially supported through the JPI Oceans project MiningImpact ?Environmental Impacts and Risks of Deep-Sea Mining? August 2018 to February 2022 (NWO-ALW grant 856.18.001 to S. G.; BMBF grant no. 03F0812A-H to M. H., F. J., M. M., A. V.). Publisher Copyright: © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
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