[M-IS22] Interactions of Geosphere-Hydrosphere-Biosphere and Deep-sea Methane Environments

[MIS22-P15] Plankton surveys near mud volcanoes in the Nankai Trough and Ryukyu Trench

*Hiromi Kayama WATANABE¹, Shino Yamamoto¹, Kingsley Jin-Ho Wong², Tong Vicki Wei³, Shumpei Hattori⁴, Ami Morita⁵, Akira Ijiri⁶ (1.Japan Agency for Marine-Earth Science and Technology, 2.Academia Sinica, Taiwan, 3.Hong Kong University of Science and Technology, 4.Kitasato University, 5.Kanazawa University, 6.Kobe University)

Keywords:Chemosynthesis-based ecosystem, Planktonic larvae, Community composition

Mud volcanoes are one of the windows that supply various materials from the subsurface layers, and methane emissions from marine mud volcanoes are expected to effect on the global climate change. On the other hand, the materials that are supplied by the marine mud volcanoes, such as methane, provide essential substances for chemosynthesis and subsequently established chemosynthesis-based communities, which consist of many endemic animal species. These animals have recently been listed as endangered due to their limited habitats—mostly in areas targeted for seabed mining, thus it is important to understand their community dynamics in consideration in conservation. Most of the animals in the chemosynthesis-based communities are benthic and their mobility is restricted in the adult stage of their life history, resulting in their patchy spatial distribution. Planktonic stages in their early life history such as embryos and larvae are important because they can be transported by oceanic current for thousands of kilometers in a relatively short period by oceanic currents. However, knowledge of the distribution of the plankton that were derived from the chemosynthesis-based communities is rather limited. In this study, we aimed to determine the vertical distribution of plankton around the various mud volcanoes in the Nankai Trough and Ryukyu Trench, and to analyze the relationship with the chemosynthesis-based communities and environments around these study areas.