Vent Fauna in the Mariana Trough

Abstract

The Mariana Trough is a back-arc basin in the Northwestern Pacific. To date, active hydrothermal vent fields associated with the back-arc spreading center have been reported from the central to the southernmost region of the basin. In spite of a large variation of water depth, no clear segregation of vent faunas has been recognized among vent fields in the Mariana Trough and a large snail Alviniconcha hessleri dominates chemosynthesis-based communities in most fields. Although the Mariana Trough approaches the Mariana Arc at both northern and southern ends, the fauna at back-arc vents within the trough appears to differ from arc vents. In addition, a distinct chemosynthesis-based community was recently discovered in a methane seep site on the landward slope of the Mariana Trench. On the other hand, some hydrothermal vent fields in the Okinawa Trough backarc basin and the Izu-Ogasawara Arc share some faunal groups with the Mariana Trough. The Mariana Trough is a very interesting area from the zoogeographical point of view.