Micromorphological variation in Pocillopora coral is associated to temporal changes of corallite development
摘要
Species identification of many reef-building corals rests on features of the corallite that change in plastic response to environmental conditions and through the course of normal colony growth. This study investigates seasonal variation and developmental progression of corallite microstructures of Pocillopora grandis from two localities with contrasting flow conditions. Analyses of electron micrographs revealed seasonal variations in the columella and septa that are linked to corallite development. We propose five distinct developmental stages, which show similar frequencies between the two sites. Two of these stages (2a and 2b) were more abundant during warmer months and at the low-flow site. Corallite diameter of stage 1 was smaller than the other stages (p < 0.001), and the diameter and depth of corallites were positively correlated (r2 = 0.98) at all stages. These findings suggest that some putatively diagnostic traits used for identification of P. grandis show seasonal variation that in turn correlates with changes in water temperature, corallite development, and reproduction. These developmental stages offer a framework for interpreting skeletal characteristics in P. grandis in terms of growth, physiology, and taxonomy under changing environmental conditions. A recognition of seasonal changes in corallite ontogeny facilitates better understanding of how microstructures can vary in response to both biological and environmental factors without necessarily reflecting plasticity.