Faunal composition of deep-sea hydrothermal vent fields on the Izu–Bonin–Mariana Arc, northwestern Pacific

Abstract

Hydrothermal vent fields in the deep-sea are highly productive and host highly specific animals adapted to chemosynthesis-based ecosystems. Knowledge on the distribution range of dominant fauna in these ecosystems help elucidate their biogeography, as well as contribute key baseline data for managing conservation strategies. Here, we report faunal compositions for two hydrothermal vent fields, Myojin-sho Caldera and the Bayonnaise Knoll, on the Izu–Bonin–Mariana (IBM) Arc, a submarine volcanic arc system in the western Pacific, and examined biogeographical subdivisions within. Similarity indices and subsequent analyses based on species presence/absence data revealed three groups, namely those in the Izu area, shallower vents in the Bonin–Mariana area, and deeper vents in the Bonin–Mariana area. This pattern of subdivision indicates that water depth and tectonic discontinuity, in this case the Sofugan Tectonic Line, contribute to the distribution ranges of vent specific animals on the IBM Arc, but the conjunction of Mariana and West Mariana ridges have little contribution. This is the first data for faunal subdivision of vents on the 9000 km-long submarine volcanic chain of the western Pacific extending further south of the IBM Arc, and further analyses on faunal distribution of other vents in this area and larval ecology of vent animals are required to understand subdivisions across the entire chain.