Systematic variations in the depth of skeleton occupied by coral tissue in massive colonies of Porites from the Great barrier reef

Abstract

The depth of skeleton occupied by tissue was measured in 284 colonies of massive Porites from 46 reefs along the length of the Great Barrier Reef. These colonies ranged in height from 42 mm to 8 m. Average tissue layer thickness was 5.43 ±1.48mm (range 2.13–10.20 mm). The thickness of the tissue layer did not vary with species. The tissue layer thinned from the summit to the sides of all but the smallest colonies. It also increased in thickness with increasing colony size and varied between location at which colonies were collected. Seasonal and year-to-year variations in tissue thickness could not be adequately separated within the data set. Despite the equivocal nature of some results, the study clearly identifies factors which must be considered in future experimental designs aimed at testing sources of variation in tissue layer thickness. Systematic variations in the depth of skeleton occupied by the tissue layer are important to understanding the development of density banding and may also provide a simple measure of the health and performance of corals and coral reefs.