Composition and biogeography of hydrothermal vent communities in Western Pacific Back-Arc Basins

Abstract

Deep-sea hydrothermal vent communities have been located and studied over different geological and dynamic contexts: fast to slow mid-ocean ridges, back-arc basins, volcanic arcs, and active seamounts. The associated vent faunas belong to a small set of mostly endemic taxa relying on chemoautotrophic microbial production, able to stand extreme habitat conditions and to persist in a discontinuous and ephemeral environment. Because of their obligate relations to hydrothermal venting, they disperse only along ridges, stepping from one active hydrothermal vent to another. Discontinuities of the ridges or hydrological barriers can limit along-axis dispersal and thus favor allopatric speciation. Western Pacific back-arc basins are isolated spreading centers, which remain active during a short period of geological time, in the proximity of active and passive continental margins where cold seeps are frequent. The Rim of Fire region thus represents a complex area of potential exchanges between chemosynthetic-based ecosystems. Our present knowledge is restricted to active areas situated in five back-arc basins (Lau and North Fiji Basins, Manus Basin, Mariana Trough, Okinawa Trough) and two are volcanoes (Izu-Ogasawara, Kermadec Arc). We here review the distribution and composition of vent-associated biological communities in these basins and arcs, and discuss the faunal affinities among them and the possible migration routes between them and the mid-ocean ridges.