Sugar enrichment provides evidence for a role of nitrogen fixation in coral bleaching

Claudia Pogoreutz, Nils Radecker, Anny Cardenas, Astrid Gärdes, Christian R. Voolstra, Christian Wild

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


The disruption of the coral-algae symbiosis (coral bleaching) due to rising sea surface temperatures has become an unprecedented global threat to coral reefs. Despite decades of research, our ability to manage mass bleaching events remains hampered by an incomplete mechanistic understanding of the processes involved. In this study, we induced a coral bleaching phenotype in the absence of heat and light stress by adding sugars. The sugar addition resulted in coral symbiotic breakdown accompanied by a fourfold increase of coral-associated microbial nitrogen fixation. Concomitantly, increased N:P ratios by the coral host and algal symbionts suggest excess availability of nitrogen and a disruption of the nitrogen limitation within the coral holobiont. As nitrogen fixation is similarly stimulated in ocean warming scenarios, here we propose a refined coral bleaching model integrating the cascading effects of stimulated microbial nitrogen fixation. This model highlights the putative role of nitrogen-fixing microbes in coral holobiont functioning and breakdown.
Original languageEnglish (US)
Pages (from-to)3838-3848
Number of pages11
JournalGlobal Change Biology
Issue number9
StatePublished - Apr 21 2017


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