Onset of sexual maturity of sexually propagated and wild colonies of the massive coral Favites abdita in northwestern Philippines

ABSTRACT Despite decades of research, many aspects of coral reproductive biology, such as colony size and age at the onset of sexual maturity remain poorly studied. In this study, wild colonies of different size classes and colonies of a known age of the massive scleractinian Favites abdita were examined for the presence or absence of mature oocytes to determine size and age at the onset of maturity. Fecundity for each size class was also determined for wild colonies. Both sexually propagated and wild F. abdita colonies that are 1.8 cm in diameter were found to be sexually mature. Colonies of size class A (0.1–4.0 cm maximum diameter) had lower mean oocyte counts but greater mean oocyte geometric mean diameter per polyp (44 ± 6.08, 340.38 ± 7.68 µm; mean ± SE) compared to colonies of classes B (4.1–8.0 cm) and C (>8.1 cm) (469 ± 62.41, 283.96 ± 6.94 µm; 278 ± 57.15, 317.57 ± 9.18 µm, respectively). Results of this study bring into question the widely applied operational definition of juveniles being colonies ≤4.0 cm diameter and suggest that even quite small colonies can play a role in contributing to the natural larval pool on reefs than previously thought.