Reproductive ecology and distribution of the scleractinian coral Fungia scutaria in Kane‘ohe Bay, O‘ahu, Hawai‘i

Abstract

In Hawaii, abundance of the scleractinian Fungia scutaria is thought to have been in decline in recent years due to disturbances to Kaneohe Bay, where an unusually dense population exists. This study examines factors that could limit population growth in this coral. Sexual reproduction occurred throughout the summer. Experimental data from sperm dilution studies suggested that eggs must be released within 2m of a spawning male for successful fertilization to occur. Field surveys indicated that many patch reefs exhibited high enough densities to yield successful fertilization. However, since field surveys found that only a small percentage (1 %) of juvenile corals (5 cm in length) resulted from settled larvae, post-fertilization processes may be limiting successful recruitment. Asexual reproduction appears to be dominant, with 70% of corals occurring in close aggregations, and 93% of these in aggregations made up of a single color-morph.