Age and growth of two genera of deep-sea bamboo corals (family Isididae) in New Zealand waters

We provide a detailed description of growth zone counts at two locations in the skeletal structure of four bamboo coral colonies (Family Isididae, subfamily Keratoisidinae, genera Lepidisis spp. and Keratoisis sp. from New Zealand). Zone counts were made microscopically on skeletal cross-sections of calcareous internodes producing counts of up to 90 for Lepidisis spp. and 160 for Keratoisis sp. Scanning Electron Microscope (SEM) images taken of cross-sections at the junction of the calcareous internode and gorgonin node revealed clear zone resolution and produced counts that were substantially higher (a maximum 490 zones). Lead-210 dating was applied to the skeletal structure of one specimen of Lepidisis sp. to develop an independent estimate of age and growth. Radial microsampling of the skeletal carbonate indicated the age of the colony at the largest section (7.4 mm average radius) was 43 yrs old (26–61 yrs 95% CI), with an average radial growth rate of 0.18 mm yr–1 (0.13–0.29 mm/yr 95% CI). Comparisons between the three age estimates for Lepidisis sp. were made and it was hypothesized that zones observed by light microscope have a bi-annual periodicity and that SEM-observed zones at the nodal juncture may represent an environmental event, such as lunar periodicity.

Tracey, D.M., H. Neil, P. Marriot, A.H. Andrews, G.M. Cailliet, J.A. Sanchez. 2007. Age and growth of two genera of deep-sea bamboo corals (family Isididae) in New Zealand waters. Proceedings of the 3rd International Symposium on Deep-Sea Corals. Bulletin of Marine Science. 81(3): 393-408.