Growth and population dynamic model of the reef coral Fungia granulosa Klunzinger, 1879 at Eilat, northern Red Sea

The lack of population dynamic information for most species of stony corals is due in part to their complicated life histories that may include fissio n, fusion and partial mortality of colonies, leading to an uncoupling of co ral age and size. However, some reef-building corals may produce compact up right or free-living individuals in which the above processes rarely occur, or are clearly detectable. In some of these corals, individual age may be determined from size, and standard growth and population dynamic models may be applied to gain an accurate picture of their life history. We measured long-term growth rates (up to 2.5 years) of individuals of the free-living mushroom coral Fungia granulosa Klunzinger, 1879 at Eilat, northern Red Sea , and determined the size structure of a population on the shallow reef slo pe. We then applied growth and population models to the data to obtain esti mates of coral age, mortality rate, and life expectancy in members of this species. In the field, few F. granulosa polyps suffered partial mortality o f > 10% of their tissues. Thus, the majority of polyps grew isometrically a nd determinately, virtually ceasing growth by about 30-40 years of age. Cor al ages as revealed by skeletal growth rings were similar to those estimate d from a growth curve based on held data. The frequency of individuals in e ach age class on the reef slope decreased exponentially with coral age, ind icating high mortality rates when corals were young. The maximum coral age observed in the field population (31 years) was similar to that estimated b y application of a population dynamic model (30 years). Calculated rates of growth, mortality and life expectancy for F. granulosa were within the ran ge of those known for other stony corals. Our results reveal a young, dynam ic population of this species on Eilat reefs, with high turnover rates and short lifespans. Such information is important for understanding recovery o f coral reefs from disturbances, and for application to the management of c ommercially exploited coral populations. (C) 2000 Elsevier Science B.V. All rights reserved.