ABSTRACT

Since 1984, dense biological communities dominated by giant vesicomyid clam, Calyptogena soyoae, have been located on 1000 to 1200m deep seabed along the foot of the western escarpment of Sagami Bay Japan, by the manned submersible, “Shinkai 2000” and deep-tow TV and photography of Japan Marine Science and Technology Center. Chemical and isotopic study of the clams, sediments and bottom seawater, sampled during the field study of the area using “Shinkai 2000” in 1986, revealed that the clam communities are in close association with methane rich seep systems and that chemoautotrophic sulfur bacteria, living symbiotically in the clam's gill tissues, play an important nutritional role for the seep communities.