Biogeography and molecular diversity of coral symbionts in the genus Symbiodinium around the Arabian Peninsula

Abstract
Aim: Coral reefs rely on the symbiosis between scleractinian corals and intracellular, photosynthetic dinoflagellates of the genus Symbiodinium making the assessment of symbiont diversity critical to our understanding of ecological resilience of these ecosystems. This study characterizes Symbiodinium diversity around the Arabian Peninsula, which contains some of the most thermally diverse and understudied reefs on Earth. Location: Shallow water coral reefs throughout the Red Sea (RS), Sea of Oman (SO), and Persian/Arabian Gulf (PAG). Methods: Next-generation sequencing of the ITS2 marker gene was used to assess Symbiodinium community composition and diversity comprising 892 samples from 46 hard and soft coral genera. Results: Corals were associated with a large diversity of Symbiodinium, which usually consisted of one or two prevalent symbiont types and many types at low abundance. Symbiodinium communities were strongly structured according to geographical region and to a lesser extent by coral host identity. Overall symbiont communities were composed primarily of species from clade A and C in the RS, clade A, C, and D in the SO, and clade C and D in the PAG, representing a gradual shift from C- to D-dominated coral hosts. The analysis of symbiont diversity in an Operational Taxonomic Unit (OTU)-based framework allowed the identification of differences in symbiont taxon richness over geographical regions and host genera. Main conclusions: Our study represents a comprehensive overview over biogeography and molecular diversity of Symbiodinium in the Arabian Seas, where coral reefs thrive in one of the most extreme environmental settings on the planet. As such our data will serve as a baseline for further exploration into the effects of environmental change on host-symbiont pairings and the identification and ecological significance of Symbiodinium types from regions already experiencing 'Future Ocean' conditions.

Citation
Ziegler M, Arif C, Burt JA, Dobretsov S, Roder C, et al. (2017) Biogeography and molecular diversity of coral symbionts in the genus Symbiodinium around the Arabian Peninsula. Journal of Biogeography. Available: http://dx.doi.org/10.1111/jbi.12913.

Acknowledgements
We thank Craig Michell for support with sequencing preparations, Till Bayer, Shobhit Agrawal, and Yi Jin Liew for advice on data parsing, Noru Moreno, Drew Wham, and Julia Schnetzer for assistance in the field, and the members of Sea Legends and the Department of Marine Sciences for their help in organizing the trips in Oman. Permits for sample collection in Oman have been issued by the Ministry of Environment and Climate Affairs (MECA). Permits for sample collection in the Red Sea have been obtained with help of the Coastal and Marine Resources Core (CMOR) lab at King Abdullah University of Science and Technology (KAUST). We extend our gratitude to the Environment Agency Abu Dhabi and the Dibba Municipality and Fujairah Municipality for permission to collect samples in the United Arab Emirates. Research reported in this publication was supported by competitive research funding from King Abdullah University of Science and Technology (KAUST), Office of Sponsored Research (OSR) under Award No. OSR-2015-CCF-1973 and an AEA3 grant to C.R.V.

Publisher
Wiley

Journal
Journal of Biogeography

DOI
10.1111/jbi.12913

Additional Links
http://onlinelibrary.wiley.com/doi/10.1111/jbi.12913/full

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