AGE AND GROWTH OF TWO GENERA OF DEEP-SEA BAMBOO CORALS (FAMILY ISIDIDAE) IN NEW ZEALAND WATERS

摘要

We provide a detailed description of growth zone counts at two locations in the skeletal structure of four bamboo coral colonies (Family Isididae, sub-family Kera-toisidinae, 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 micro-sampling 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~(-1) 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.