Effect of colony size and age on resource allocation between growth and reproduction in the corals Goniastrea aspera and Favites chinensis

The effect of colony size and age on growth and sexual reproduction was examined by taking small-sized fragments from large mature donor colonies of Goniastrea aspera and Favites chinensis. Both species are massive colonial corals in the family Faviidae. Monopolyp and oligopolyp (5 to 8 polyps) fragments were established. The fragments were cultured in running seawater aquaria for 22 mo, and growth and gamete production were measured. In both species, monopolyp fragments had higher growth rates than oligopolyp fragments. F. chinensis had higher growth rates than G. aspera in both fragment sizes. Polyps tended to bud when there was open space, and smaller colonies had higher growth rates, probably because the polyps of smaller colonies had more open space. In G. aspera, both the monopolyp and oligopolyp fragments produced gametes, whereas in F. chinensis, neither type of fragment produced gametes. These results suggest that sexual maturity is determined by colony age in G. aspera and by colony size in F. chinensis. Our results also suggest that polyps are integrated at the colony level. Polyp integration activity in a colony may be determined by the age of the colony in G. aspera and by the size of the colony in F. chinensis, likely maximizing colony fitness.