Diversity of free-living and symbiotic Symbiodinium in the coral reefs of Sanya, South China Sea

Abstract

Unicellular photosynthetic dinoflagellates from the genus Symbiodinium are found either free-living or in hospite with a wide variety of marine invertebrate hosts including scleractinian corals. The linkages between free-living and endosymbiotic Symbiodinium remain largely unstudied and constitute a major gap in knowledge. In this study, the diversity of free-living Symbiodinium spp. and those associated with scleractinian corals from coral reefs in Sanya CRNR, South China Sea were determined by Symbiodinium-specific primers for the hypervariable region of the chloroplast 23S domain V (cp23S-HVR). The results illustrated that the free-living Symbiodinium spp. were highly spatially heterogeneous with high diversity related to clades A, B, C, D, F, G and H. However, the reef corals mainly hosted only one symbiont type of either clades C or D, and few species could harbour both concurrently. Surprisingly, Symbiodinium spp. in scleractinian corals were totally different from free-living forms in adjacent waters. These results suggest that the corals did not recruit Symbiodinium spp. from adjacent waters and the exchange of Symbiodinium spp. between corals and waters is limited in this region.

Keywords:

• Coral
• free-living Symbiodinium
• diversity
• resilience

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank the administration and staff of the Sanya National Coral Reef Nature Reserve, China for permit and logistical support. Particularly, Yuyang Zhang and Ting Su are acknowledged for their assistance during the sample collection and experiments. We are grateful to Zhao Sun and Jingbin Feng for valuable discussions. This work was supported by grants from the National Natural Science Foundation of China (Nos. 40776085, 40830850) and the Main Direction Program of Knowledge Innovation of Chinese Academy of Sciences (No. KZCX2-YW-227).

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark