Growth rate and age determination of bamboo corals from the northeastern Pacific Ocean using refined 210Pb dating

Bamboo corals from Davidson Seamount and from the Gulf of Alaska were aged using a refined Pb-210 dating technique. The goal was to determine growth rates and age for several bamboo corals with higher precision. Radiometric results for 2 Davidson Seamount corals (Keratoisis sp.) converged on a radial growth rate of similar to 0.055 mm yr(-1). One colony was aged at 98 +/- 9 yr, with an average axial growth rate of similar to 0.7 cm yr(-1). The age of a large colony was > 145 yr with an estimated axial growth rate of 0.14 to 0.28 cm yr(-1). Inconsistent rates may indicate nonlinear axial growth. A Keratoisis sp. specimen from the Gulf of Alaska was aged at 116 +/- 29 yr from a radial growth rate of similar to 0.056 mm yr(-1), which led to an average axial growth rate of similar to 1.0 cm yr(-1). An Isidella tentaculum colony was aged at 53 +/- 10 yr and grew most rapidly with a radial growth rate of similar to 0.10 mm yr(-1) and an average axial growth rate of similar to 1.4 cm yr(-1); however, the Pb-210 decay pattern may have provided evidence for either a hiatus in radial growth or environmental changes in Pb-210. Our findings of slow growth and long life compared favorably with other bamboo coral studies and provided age estimates with greater precision. The high longevity of bamboo coral is an indication that recovery from disturbance or removal may take decades to a century. These age data provide a basis for a defensible position on the protection of bamboo coral and essential information for describing other life history characteristics.