UC Irvine

We measured carbon isotope abundances in the layered, proteinaceous skeleton of a zoanthid Gerardia collected from 620 m depth off the Little Bahama Bank (27°N, 79°W). The δ 14C values decreased from -76% in the outer growth edge to an average of -267% in the center of three portions of the skeleton. These δ 14C data suggest an age for this living organism of 1800 ± 300 years. The possibility that the large decrease in δ 14C reflects the gradual input of bomb 14C over the entire growth of the organism is inconsistent with the post-bomb δ 14C values obtained for the most recent growth tips. If the age estimate of two millennia is correct, it may be the longest-lived animal yet observed in the ocean. Gerardia may serve as a long-lived recorder of ocean chemistry, similar to the Bristlecone pine tree that has served as a millennial-timescale recorder for atmospheric 14CO2 (Suess, 1980) and climate. In particular, there is potential for Gerardia to serve as a millennial-scale integrator of upper ocean particle flux, and possibly reveal past changes in the productivity of the surface ocean. © 1995.