Worldwide Occurrence and Activity of the Reef-Building Coral Symbiont Symbiodinium in the Open Ocean
Voolstra, Christian R.
de Vargas, Colomban
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Marine Science Program
Red Sea Research Center (RSRC)
Online Publication Date2018-11-08
Print Publication Date2018-11
Permanent link to this recordhttp://hdl.handle.net/10754/630601
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AbstractThe dinoflagellate microalga Symbiodinium sustains coral reefs, one of the most diverse ecosystems of the biosphere, through mutualistic endosymbioses with a wide diversity of benthic hosts . Despite its ecological and economic importance, the presence of Symbiodinium in open oceanic waters remains unknown, which represents a significant knowledge gap to fully understand the eco-evolutionary trajectory and resilience of endangered Symbiodinium-based symbioses. Here, we document the existence of Symbiodinium (i.e., now the family Symbiodiniaceae ) in tropical- and temperate-surface oceans using DNA and RNA metabarcoding of size-fractionated plankton samples collected at 109 stations across the globe. Symbiodinium from clades A and C were, by far, the most prevalent and widely distributed lineages (representing 0.1% of phytoplankton reads), while other lineages (clades B, D, E, F, and G) were present but rare. Concurrent metatranscriptomics analyses using the Tara Oceans gene catalog  revealed that Symbiodinium clades A and C were transcriptionally active in the open ocean and expressed core metabolic pathways (e.g., photosynthesis, carbon fixation, glycolysis, and ammonium uptake). Metabarcodes and expressed genes of clades A and C were detected in small and large plankton size fractions, suggesting the existence of a free-living population and a symbiotic lifestyle within planktonic hosts, respectively. However, high-resolution genetic markers and microscopy are required to confirm the life history of oceanic Symbiodinium. Overall, the previously unknown, metabolically active presence of Symbiodinium in oceanic waters opens up new avenues for investigating the potential of this oceanic reservoir to repopulate coral reefs following stress-induced bleaching.
CitationDecelle J, Carradec Q, Pochon X, Henry N, Romac S, et al. (2018) Worldwide Occurrence and Activity of the Reef-Building Coral Symbiont Symbiodinium in the Open Ocean. Current Biology 28: 3625–3633.e3. Available: http://dx.doi.org/10.1016/j.cub.2018.09.024.
SponsorsThis work was supported by the project OCEANOMICS and France Génomique, which received funding from the French government, managed by the Agence Nationale de la Recherche, under the grant agreement “Investissement d’Avenir” (grants ANR-11-BTBR-0008 and ANR-10-INBS-09). J.D. has been supported by the European Union’s Horizon 2020 research and innovation programme, under the Marie Sklodowska-Curie grant agreement 658442 (MSCA-IF-2014), and by the LabEx GRAL (ANR-10-LABX-49-01) and Pȏle CBS from the University of Grenoble Alpes. We thank the coordinators and members of the Tara Oceans consortium and Giovanni Finazzi and Ian Probert for critical reading of the manuscript. This article is contribution number 78 of Tara Oceans.