Vent Fauna in the Okinawa Trough

Abstract

In deep-sea hydrothermal vent fields, faunal distribution is associated with geochemical environments generated by hydrothermal vent activity. The Okinawa Trough is located between the Eurasian Continent and the Ryukyu Arc, and is characterized by sediment-associated fauna associated with vents. In this chapter, the faunal distribution in hydrothermal vent fields in the Okinawa Trough is summarized at inter- and intra-field levels, and its relationship with geochemical environments and species-specific ecologies is discussed. Although the zonation of sediment-associated fauna is not distinct, the fauna on rocky seabed can be categorized into four zones based on thermal conditions. Genetic connectivity among conspecific populations in the Okinawa Trough appears to be common; further, a few faunal groups, such as tubeworms, show connectivity to regions outside of the Okinawa Trough. The faunal composition of vent communities in the Okinawa Trough has been categorized into three groups: the Minami-Ensei Knoll, Yoron Hole, and middle-southern Okinawa Trough. To determine more precisely the relationships between faunal composition and environmental factors in the Okinawa Trough vent fields, both generalized and vent-specific environmental factors should be measured simultaneously with quantitative faunal sampling for analyses.