GERARDIA - BRISTLECONE-PINE OF THE DEEP-SEA

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 degrees N, 79 degrees W). The Delta(14)C values de creased from -76 parts per thousand in the outer growth edge to an average of -267 parts per thousand in the center of three portions of the skeleton. These Delta(14)C data suggest an age for this living organism of 1800 +/- 300 years. The possibility that the large decrease in Delta(14)C reflects the gradual input of bomb C-14 over the entire growth of the organism is inconsistent with the post-bomb Delta(14)C values obtained for the most recent growth tips. If the age estimate of two millennia is comet, 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 (CO2)-C-14 (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.