Bamboo coral age and growth
Bamboo coral of Davidson Seamount and Alaska
Published in Marine and Ecological Progress Series 2009
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 210Pb 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 ~0.055 mm yr–1. One colony was aged at 98 ± 9 yr, with an average axial growth rate of ~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 ~0.056 mm yr–1, which led to an average axial growth rate of ~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 ~0.10 mm yr–1 and an average axial growth rate of ~1.4 cm yr–1; however, the 210Pb decay pattern may have provided evidence for either a hiatus in radial growth or environmental changes in 210Pb. 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.
Keratoisis sp. and Isidella tentaculum. (a) Lower portion of the Keratoisis sp. GOA99 bamboo coral colony after cleaning. (b) Lower portion of the I. tentaculum GOA107 bamboo coral colony after cleaning. Sections for each colony were taken from internode segments near the base
Diagram of the extraction sample design used to maximize collection of material for a given formational period. This method was applied to colonies D06 and GOA107. The chosen cylindrical segment was cut into 4 to 6 sections (A–F). Each section was sampled successively in a radial manner with the micromill from the edge to the core 1–8. This approach was necessary because of physical limitations on drill bit depth (tapered shank diameter) and the extractions were only possible with the fine resolution attainable with a New Wave Research micromilling machine (Elemental Scientific Lasers, Bozeman, MT, USA; http://www.nwrlasers.com/milling/micromill/).
A.H. Andrews, R.P. Stone, C.C. Lundstrom, A.P. DeVogelaere. 2009. Growth rate and age determination of bamboo corals from the northeastern Pacific Ocean using refined 210Pb dating. Mar. Ecol. Prog. Ser. 397: 173–185.
