Geographic distribution of zooxanthella types in three coral species on the Great Barrier Reef sampled after the 2002 bleaching event

• Published in: Coral reefs Vol. 24; no. 3; pp. 482 - 487
• Main Authors: VAN. OPPEN, Madeleine J. H, MAHINY, Azita J, DONE, Terry J
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-11-2005; Berlin Springer Nature B.V
• Subjects: Acropora millepora; Acropora tenuis; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Cnidaria. Ctenaria; Fundamental and applied biological sciences. Psychology; Geographical distribution; Invertebrates; Marine; Sea water ecosystems; Stylophora pistillata; Symbiodinium; Synecology; Australia; Oceania; Great Barrier Reef; ISEW, Australia, Queensland, Great Barrier Reef; ISEW, Australia, Queensland; Coelenterata; Geographic distribution; Bleaching; Coral; Cnidaria; Coral reef; Invertebrata; Great Barrier Reef
• ISSN: 0722-4028; 1432-0975
• DOI: 10.1007/s00338-005-0487-1

Reef corals form obligate symbiotic relationships with many genetically divergent taxa of zooxanthellae (dinoflagellates of the genus Symbiodinium). Based on nuclear ribosomal DNA (rDNA) and later confirmed by partial chloroplast large subunit rDNA sequences, eight distinct phylogenetic clades of zooxanthellae have been distinguished (A-H), five of which (A-D, F) are known to form associations with scleractinian corals. This high taxon diversity is accompanied by differences in physiological traits between some zooxanthella types with Symbiodinium clade D being the most heat tolerant type known today. Physiological differences among zooxanthella types has led to the expectation that zooxanthella types may affect their hosts' sensitivity to environmental conditions and/or that changes in environmental conditions may affect the distribution of zooxanthella types. In January and February 2002, the Great Barrier Reef (GBR) was exposed to an extended period of elevated sea water temperature and high light that led to widespread but patchy coral bleaching (expulsion of zooxanthellae by the coral host and/or loss of zooxanthellar pigments). To search for possible links between the zooxanthella type harbored by the coral colonies and the extent of damage suffered from the bleaching event, and also to explore patterns of zooxanthella distribution, the authors sampled zooxanthellae from three common species of scleractinian corals, Acropora millepora, A. tenuis and Stylophora pistillata, from 17 sites along a latitudinal and cross-shelf gradient in the central and southern sections of the GBR 4- 5 months after the 2002 bleaching event. The health status of each coral colony was recorded at the time of collection, and its zooxanthella genotype identified, using single stranded conformation polymorphism and sequence analysis of the nuclear ribosomal DNA ITS1 region. There were no simple correlations between symbiont types and either the level of bleaching of individual colonies or indicators of heat stress at individual sites. However, there was a very high post-bleaching abundance of the heat tolerant symbiont type D in one coral population at the most heat stressed site.