Growth rates and growth strategy in a clonal marine invertebrate, the Caribbean octocoral Briareum asbestinum

Measured the growth rates of colonies on Pinnacles and House Reef in the San Blas Islands, Panama. Colonies grew at a net rate of 16.6 cm.yr and added 1.2 branches/yr. Individual branch measurements yielded a net rate of growth of 2.02 cm/yr/branch. Positive growth rates, which provide a measure of minimum potential growth, were 71.3 cm/yr and 8.7 branches/yr for colonies and 6.21 cm/yr for individual branches. Net growth rates and branch addition rates were 76 and 85% less than potential growth rates indicating large losses to fragmentation and predation. Calculated mean longevity of individual colonies (ramets) is short (10.6 yr) given observed rates of growth and loss, but since fragmented branches can reattach and initiate new colonies, losses due to fragmentation contribute to the asexual expansion of the genet. The independence of branch growth ahd size may reflect the diversion of energy away from growth toward reproduction. As a consequence of this pattern, bifurcating growth forms will, on a colony basis, grow more rapidly and amass more reproductive tissue than simple linear extension. However, the short longevity of ramets limits the advantage to be gained from accumulating reproductive tissue by rapid branch bifurcation. -from Authors