Coral population structure: the hidden information of colony size-frequency distributions

Analyses of coral colony size-frequency distributions reveal important characteristics of populations on the reef. Coral colony size-frequencies can be modelled by log normal distributions and coral populations can be described by statistics of frequency distributions such as coefficient of variation, skewness and mode. Coefficient of variation allows comparison of variation in coral populations of different mean colony size. Skewness reflects the proportion of small versus larger colonies, representing juvenile input and longevity. The mode in the size-frequency distributions represents the most frequent colony size. The mode appears indicative of a change in the relative impact of total and partial mortality in coral populations. These size-frequency variables differ significantly between coral species and, within species, between reef localities. Coral colony size-frequency diagrams provide insight into past events and have some predictive power with respect to population development. Our data demonstrate that measurement of the above-mentioned variables could be a tool to estimate the response of coral populations to the reef environment.