December 14, 2000
Japan Marine Science and Technology Center

Discovery of hydrothermalism and hydrothermal vent communities in the Indian

On December 14, 2000, the Japan Marine Science and Technology Center (JAMSTEC) announced discovery of hydrothermal vents gushing out superheated water (360BC at maximum) and associated biological communities in the Indian Ocean. Since the first discovery of vent communities at the Galapagos Rift in 1977, many deep-sea hydrothermal vent communities have been reported from the Pacific and Atlantic Oceans. However, active hydrothermal vents and associated communities had not been located in the Indian Ocean in spite of many research cruises organized by and with Germany, France, Japan and other countries. A research cruise using the R/V Kairei and the ROV Kaiko was carried out to search for hydrothermalism in the Indian Ocean by a research team consisting of biologists, geochemists and geophysicists from JAMSTEC and other Japanese Universities from August to September in 2000. During the cruise, extremely active vent sites with biological communities were discovered close to the Rodriguez Triple Junction (the plate boundary between the African, Antarctic and Indo-Australian Plates), located towards the center of the Indian Ocean, at a depth of 2450m. Hydrothermal vents with biological communities were distributed in a 40 m by 80 m field(Picture1). Dense swarms of Rimicaris shrimps, and numbers of actinians and Alviniconcha snails were found and captured around the vent sites(Picture2). Most biological samples are supposed to be new species. The discovery of active hydrothermalism with associated hydrothermal vent communities in the Indian Ocean will yield significant advances in our understanding of deep-sea biology as well as that of geochemistry including the influence of hydrothermalism to the ocean environment.

for further information:
Dr. Hashimoto and Tsuchida, Marine Ecosystems Research Department
(Phone: 81-468-67-3844)
Mr. Taya, and Tsukioka
Public Relations, Training and Education Division, Administration Department
(Phone: 81-468-67-3806)