The megafauna community from an abyssal area of interest for mining of polymetallic nodules.

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Publisher: Elsevier B.V.
Document Type: Report
Length: 429 words

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Keywords Megafauna; Deep-sea mining; Polymetallic nodules; CCZ; Biodiversity; Community structure; Deep sea; AUV Highlights * Images taken above 8m altitude underestimate the megafauna density by almost 50% compared to images * A general positive relationship between nodule coverage and megafauna abundance was observed across the two GSR areas. * Differences in megafaunal composition were mainly caused by differences in echinoderms, representing almost 70%. Abstract Polymetallic nodules increase habitat heterogeneity in some abyssal benthic ecosystems by providing hard substrate. Besides their important role in structuring ecosystems, polymetallic nodules have high grades of valuable minerals and are a target of likely future exploitation, particularly in the Pacific Clarion-Clipperton Zone (CCZ). Mining activities will remove hard substrate and sediment and cause sediment plumes potentially affecting faunal communities over large areas. Long-lived megafaunal assemblages may be particularly vulnerable but data are lacking on the density, biodiversity and community structure in many areas of the CCZ. This study aims to provide megabenthic community baseline data from two physically similar areas (B6S02 and B4S03) located in the contract area of Global Sea Mineral Resources N.V. (GSR). Seafloor images, obtained by an autonomous underwater vehicle are used to characterise the large areas required for robust evaluation of sparse megafauna. Higher altitude images cover a larger area for the same effort but have reduced resolution compared to images obtained closer to the seafloor, leading to difficulties in detecting and identifying individuals. Our comparison of images obtained at different altitudes shows that images taken above 8m altitude underestimate the megafauna density by almost 50%, so images Author Affiliation: (a) Department of Biology, Marine Biology Research Group, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium (b) Flanders Marine Institute, Wandelaarkaai 7, 8400, Oostende, Belgium (c) National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom * Corresponding author. Flanders Marine Institute, Wandelaarkaai 7, 8400 Oostende, Belgium. Article History: Received 7 July 2020; Revised 29 January 2021; Accepted 26 March 2021 Byline: Bart De Smet [] (a,b,*), Erik Simon-Lledó [] (c), Lisa Mevenkamp [] (a), Ellen Pape [] (a), Francesca Pasotti [] (a), Daniel O.B. Jones [] (c), Ann Vanreusel [] (a)

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Gale Document Number: GALE|A663043944