Discovery of the dendrophylliid scleractinian Heteropsammia cochlea (Spengler, 1781) in Halimeda bioherms of the Northern Great Barrier Reef

Abstract

AbstractHalimeda bioherms on the Northern Great Barrier Reef (GBR) extend for over 6000 km2. To explore the ecological and biogeographical importance of these bioherms was one of the aims of a recent voyage on the Research Vessel (RV) Investigator. Through the use of underwater images and habitat sampling, we found populations of Heteropsammia cochlea (Spengler, 1781) living in the bioherms. The scleractinian coral genus Heteropsammia (Dendrophylliidae) is a group of solitary, apozooxanthellate, single-polyp corals with a widespread distribution in tropical and sub-tropical regions. Populations of H. cochlea were observed with individuals dispersed on open-sand habitat and among patches of Halimeda at 30–40 m water depth in mean densities of 89 and 29 corals per m2, respectively. Fluorescence microscopy was used to assess the presence of zooxanthellae, indicating that they are actively photosynthesising at these depths. These are the first observations of H. cochlea in association with the Halimeda bioherms on the Northern GBR.