Redwood of the reef: growth and age of the giant barrel sponge Xestospongia muta in the Florida Keys

摘要: The growth of animals in most taxa has long been well described, but the phylum Porifera remained a notable exception. giant barrel sponge Xestospongia muta dominates Caribbean coral reef communities, where it is an important spatial competitor, increases habitat complexity, and filters seawater. It called 'redwood reef' because its size (often(1 m height diameter) presumed life, very little known about demography. Since 1997, we have estab- lished monitored 12 permanent 16 diameter circular transects on slope off Key Largo, Florida, to study this species. Over 4.5-year interval, mea- sured volume 104 tagged sponges using digital images determine rates X. muta. Five models were fit cubed root initial final esti- mates which best described growth. Additional measurements 33 taken over 6-month intervals examine relationship between spongocoel, or inner-osculum space, size, short-term dynamics. Sponge volumes ranged from 24.05 80,281.67 cm 3 . Growth was variable, specific decreased with increasing size. mean rate 0.52 ± 0.65 year -1 , grew as fast slow 404 2% Negative occurred short temporal scales varied seasonally, significantly faster during summer. No differences found at three different depths (15, 20, 30 m) two sites. Spongocoel positively allometric scaling vertical horizontal dimensions indicated that morphology changes frustum cone cylindrical increases. by general von Bertalanffy Tanaka curves. largest within our (1.23 9 0.98 estimated be 127 years old. Although age extra- polations for large are subject more error, reefs may excess 2,300 years, placing among longest-lived earth.