Influence of size and seasonal factors on the growth of the deep-sea coral Flabellum alabastrum in mesocosm

Growth rate (linear skeleton extension) was determined in live specimens of the deep-sea cup coral Flabellum alabastrum (Anthozoa: Flabellidae) collected between 600 and 1,200 m off insular Newfoundland (eastern Canada) and kept under laboratory conditions for over 2 years. Smaller individuals grew faster (~5 mm year⁻¹) than larger ones (~1 mm year⁻¹). Seasonal variations in extension rates and qualitative appearance of the growth bands were recorded, with maximum extension occurring in late summer and early fall during maxima in seawater temperature, zooplankton levels, and deposition of suspended detritus. Estimates from a growth model indicate that the largest individuals of F. alabastrum (~43 mm calyx height) are at least 45 years old.