Photosymbiosis and the expansion of shallow-water corals

• DOI: 10.1126/sciadv.1601122
• Publication Date: 2016-11-03T02:04:37Z
• Authors: Katarzyna Frankowiak; Xingchen T. Wang; Daniel M. Sigman; Anne M. Gothmann; Marcelo V. Kitahara; Maciej Mazur; Anders Meibom; Jarosław Stolarski
• Keywords: Dinoflagellate; Hermatypic coral; Anthozoa

Roughly 240 million years ago (Ma), scleractinian corals rapidly expanded and diversified across shallow marine environments. The main driver behind this evolution is uncertain, but the ecological success of modern reef-building attributed to their nutritional symbiosis with photosynthesizing dinoflagellate algae. We show that a suite exceptionally preserved Late Triassic (ca. 212 Ma) coral skeletons from Antalya (Turkey) have microstructures, carbonate 13C/12C 18O/16O, intracrystalline skeletal organic matter 15N/14N all indicating symbiosis. This includes species growth forms conventionally considered asymbiotic. nitrogen isotopes further suggest Tethys Sea habitat was nutrient-poor, low-productivity environment in which photosymbiosis would be highly advantageous. Thus, coral-dinoflagellate likely key expansion shallow-water scleractinians.