ABSTRACT

Sulfur isotope composition (δ³⁴S) was measured for soft tissues of Calyptogena soyoae from a cold seep off Hatsushima Islands, Sagami Bay, central Japan. The δ³⁴S values of soft tissues of six specimens collected from one colony greatly but systematically vary from one specimen to another, i.e., gill, -29.1 to -17.2; adductor, -28.0 to -24.5; foot, -17.2 to -15.2; mantle, -10.6 to -7.8‰. The observed isotopic variation between adductor, foot and mantle of a single specimen was interpreted in terms of assimilation of sulfur of different sources; biogenic hydrogen sulfide with lower δ³⁴S (around -20‰) and seawater-sulfate with higher δ³⁴S (+20‰) values.