Population dynamics of the mushroom coral Heliofungia actiniformis in the Spermonde Archipelago, South Sulawesi, Indonesia

The fungiid Heliofungia actiniformis is one ofthe most popular coral species in the Indonesian aquariumtrade, yet information on the biology of this species islimited. H. actiniformis growth rates, population sizefrequencydistributions and the seasonality of recruitmentrates were measured at three replicate sites in the SpermondeArchipelago, South Sulawesi. Growth and populationmodels were applied to estimate coral ages, mortalityrates and the size of maximum yield. Growth decreasedlinearly with polyp size. High numbers of attached polypsbudded from clusters of stalks attached to the reef, witheach cluster originating from the settlement of a sexuallyproduced larva. Neither the settlement of sexual recruits,nor their asexual budding, showed seasonality. The overallpopulation structure reflected the high mortality rates ofyoung, attached polyps (Z = 0.50.6 yr-1), and the muchlower mortalities of free-living individuals (Z = 0.050.08 yr-1). There were no statistically significant differencesin overall mortality rates and the agefrequencydistributions of polyps aged 015 years between the sites.Differences in the abundance of large H. actiniformispolyps at the three replicate sites were correlated withpercent cover of coral rubble. The application of the Bevertonand Holt model revealed the highest biomass per H. actiniformis recruit was 12 cm, corresponding to apolyp age of 20 years.