[M-ZZ44] Marine manganese deposits - Genesis, exploration and development

[MZZ44-P01] C and N stable isotope ratios of deep-sea organisms at Northwest Pacific seamounts with Co-rich ferromanganese crusts

*Nozomu Iwasaki¹, Seongwon Lee¹, Atsushi Suzuki², Shogo Kato³, Hiroyuki Yokooka³, Shota Mitsui⁴, Jumpei Minatoya⁵, Iguchi Akira², Miyuki Nishijima² (1.Faculty of Geo-Environmental Science, Rissho University, 2.Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 3. IDEA Consultants, Inc., 4.Marine Biological Research Institute of Japan Co., Ltd., 5.Japan Organization for Metals and Energy Security (JOGMEC))

Keywords:Seamounts, Cobalt-rich ferromanganese crust, Carbon and nitrogen isotope ratios, Trophic level

In this study, carbon and nitrogen isotope ratios were analyzed to clarify the carbon sources and trophic levels of deep-sea organisms occurring at seamounts with cobalt-rich ferromanganese crusts in the Northwest Pacific. Samples were collected by a remotely operated vehicle and baited traps on the seamount flats of Takuyo-Daigo Seamount and Maloney (JA04), Xufu (JA06), and Zhinyu (JA12) guyots. Snubnosed eels collected at Takuyo-Daigo Seamount were divided into two groups, one with high nitrogen stable isotope ratios and the other with low nitrogen stable isotope ratios, suggesting that each snubnosed eel group feeds on a different food and that they are carrion feeders. The sponges had higher nitrogen stable isotope ratios than suspension feeders such as corals and sea anemones, suggesting that the sponges may be carnivores.