[M-ZZ57] Marine Manganese Minerals: Science, Engineering and Application

[MZZ57-06] Application of Edokko Mark I to biodiversity evaluation of deep-sea megafauna and amphipods at Arnold and Scripps guyots with cobalt-rich ferromanganese crusts in the Northwest Pacific

*IKEUCHI ERI¹, Akira Igichi¹, Hiroyuki Yokooka², Hideki Sugishima², Kazumasa Ikeda³, Ryuichi Miwa⁴, Miyuki Nishijima¹, Nozomu Iwasaki⁵, Yuichiro Tanaka¹, Taiga Kunishima^1,6, Shogo Kato⁷, Junpei Minatoya⁷, Yoshiaki Igarashi⁷, Nobuyuki Okamoto⁷, Atsushi Suzuki¹ (1.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, 2.IDEA Consultants, Inc., 3.Okamoto Glass Co., Ltd., 4.Kaiyo Engineering Co., Ltd., 5.Faculty of Geo-Environmental Science, Rissho University, 6.Wakayama Prefectural Museum of Natural History, 7.Japan Oil, Gas and Metals National Corporation)

Keywords:Cobalt-rich ferromanganese crust, Edokko Mark I, megafauna, amphipods

To obtain high-resolution images of deep-sea megafauna and compare biodiversity between seamounts with cobalt-rich ferromanganese crusts, we deployed a free-fall deep-sea camera lander known as “Edokko Mark I.” We confirmed 32 taxa including Cnidaria, Annelida, Arthropoda, Echinodermata, and Vertebrata from the Arnold and Scripps guyots (seamounts JA03 and JA17). The community structures of megafauna clearly varied among depths. In addition, we mounted a custom-made cylinder-type baited trap on Edokko Mark I to simultaneously collect deep-sea amphipods, which are diversified group in deep-sea area. We succeeded in collecting many amphipods specimens, likely including several species with different life characters. With these amphipod specimens, DNA barcoding and MOTUs community analysis detected different community structures among depths and seamounts. Our trial with “Edokko Mark I around cobalt-rich ferromanganese crusts demonstrates its potential for facilitating environmental baseline studies and impact assessments in consideration of future deep-sea mining projects.