Size-Class Distributions of Coral

The size-class distribution of corals at a given site, assessed in combination with knowledge of species occurrence, can be informative in inferring ecological processes that are presently operative at the site. For example, a distribution in which the preponderance of corals occurs within large size classes suggests a region in which disturbance events have not interfered with the growth of corals over long periods of time. Conversely, a distribution in which the preponderance of corals occurs within small size classes suggests either a recent, severe disturbance or frequent recurrences of moderate disturbance, after which recruitment and growth have been relatively recent processes. Size-class distributions, however, must always be interpreted within the context of species-specific life history strategies as well as the salient environmental regimes to which the corals are exposed. ; For example, members of many genera, such as Pocillopora, attain only a moderate maximum size before senescence occurs even in the absence of disturbance events, whereas many large Porites heads escape the effects of severe disturbance such as typhoons due to their massive size. The size-class distribution of a species' population exposed to frequent high-energy waves will likely differ from the size-class distribution of that same species found in a more protected location. Size-class distributions of Acropora on the forereef, backreef, and lagoon at French Frigate Shoals in the Northwestern Hawaiian Islands demonstrate such differences: