Coral microbiome diversity reflects mass coral bleaching susceptibility during the 2016 El Niño heat wave

Stephanie G. Gardner, Emma F. Camp, David J. Smith, Tim Kahlke, Eslam O. Osman, Gilberte Gendron, Benjamin Hume, Claudia Pogoreutz, Christian R. Voolstra, David J. Suggett

Research output: Contribution to journalArticlepeer-review

57 Scopus citations

Abstract

Repeat marine heat wave-induced mass coral bleaching has decimated reefs in Seychelles for 35 years, but how coral-associated microbial diversity (microalgal endosymbionts of the family Symbiodiniaceae and bacterial communities) potentially underpins broad-scale bleaching dynamics remains unknown. We assessed microbiome composition during the 2016 heat wave peak at two contrasting reef sites (clear vs. turbid) in Seychelles, for key coral species considered bleaching sensitive (Acropora muricata, Acropora gemmifera) or tolerant (Porites lutea, Coelastrea aspera). For all species and sites, we sampled bleached versus unbleached colonies to examine how microbiomes align with heat stress susceptibility. Over 30% of all corals bleached in 2016, half of which were from Acropora sp. and Pocillopora sp. mass bleaching that largely transitioned to mortality by 2017. Symbiodiniaceae ITS2-sequencing revealed that the two Acropora sp. and P. lutea generally associated with C3z/C3 and C15 types, respectively, whereas C. aspera exhibited a plastic association with multiple D types and two C3z types. 16S rRNA gene sequencing revealed that bacterial communities were coral host-specific, largely through differences in the most abundant families, Hahellaceae (comprising Endozoicomonas), Rhodospirillaceae, and Rhodobacteraceae. Both Acropora sp. exhibited lower bacterial diversity, species richness, and community evenness compared to more bleaching-resistant P. lutea and C. aspera. Different bleaching susceptibility among coral species was thus consistent with distinct microbiome community profiles. These profiles were conserved across bleached and unbleached colonies of all coral species. As this pattern could also reflect a parallel response of the microbiome to environmental changes, the detailed functional associations will need to be determined in future studies. Further understanding such microbiome-environmental interactions is likely critical to target more effective management within oceanically isolated reefs of Seychelles.
Original languageEnglish (US)
Pages (from-to)938-956
Number of pages19
JournalEcology and Evolution
Volume9
Issue number3
DOIs
StatePublished - Jan 17 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We wish to extend our greatest thanks to the Seychelles National Parks Authority (SNPA) for unparalleled support across all years in generation of the annual ecological assessments, and sample collection in 2016. Also, we are indebted to the Seychelles Ministry for Environment, Energy and Climate for permitting non-commercial transfer of genetic material of analysis or this publication. We also thank Craig Michell for sequencing library preparation and the KAUST Bioscience Core Lab (BCL) for sequencing. Data collection, analysis and write up was supported by The Earthwatch Institute and the Mitsubishi Corporation (DJSm), an Endeavour Fellowship (EFC), an ARC Discovery Grant (DJSu; DP160100271) as well as a KAUST baseline research funds to CRV

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