δ13C, δ15N and δ18O of Calyptogena phaseoliformis (bivalve mollusc) from the Ascension Fan-Valley near Monterey, California

The δ13C and δ15N of the soft tissues of two Calyptogena phaseoliformis specimens sampled from the floor of Ascension Fan-Valley, off the Monterey Peninsula, California, ranged from -35.0 to -33.6% and -6.2 to -0.6%, respectively. The carbon isotope abundances are similar to those of other Calyptogena known or believed to be nutritionally dependent on sulfide-based chemoautotrophic symbionts. Calyptogena δ15N values and their geographic variation indicate an unusual source of dietary nitrogen for these animals. The δ13C and δ18O values for Calyptogena shells from the Ascension and Monterey Fan-Valleys approximate those reported for Calyptogena from three other locations in the Pacific and appear to reflect shell formation from constituents within ambient deep-ocean water.