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

[MIS22-P17] Species compositions and distribution patterns of gastropods on deployed whale carcasses
at the Tsukumo Bay, Noto Peninsula, Japan

Haruka Fukaki², *Robert Jenkins¹ (1.School of Geosciences and Civil Engineering, College of Science and Engineering, Kanazawa University, 2.Geosciences and Civil Engineering, Graduate School of Natural Science and Technolkogy, Kanazawa University)

Keywords:Whale-fall community, Gastropods, species diversity, Shallow waters

Unique biological communities have been established upon whale-falls on sea floor. The communities are called whale-fall communities. Compared to the communities in the deep-sea, shallow water communities haven't been investigated well. Thus, we have deployed several whale-carcasses on muddy seafloor at 16 m deep at the Tsukumo Bay, northeastern side of Noto Peninsula, in 2020 and 2023. We recovered several bones time to time and analyzed species diversity and abundance of gastropods in/on/around the bones. Surface sediments nearby and at least 10 m away from the carcasses were recovered. Sediments 10 m away from the carcasses are used for background faunal compositions. We identified the obtained gastropods at the species level to the best of our ability.
As a result, Finella cf. pupoides, Sticteulima cf. lentiginosa, Xenoskenea sp. and one species of Cerithiidae were characteristically found around/on the carcasses. Among the species, Xenoskenea sp. were found only from the surface of the bones, and the Finella cf. pupoides were dominantly and characteristically found sediments from 10 m away from the carcasses. Almost no gastropods were found form inside the bones. On the seafloor, both species diversity and abundance of the gastropods were high near the carcasses compared to the background. In addition, species compositions on the whale-carcasses in later decaying stages are similar to compositions on seafloor nearby the carcasses in early decaying stages.