Stimulated respiration and net photosynthesis in Cassiopeia sp. during glucose enrichment suggests in hospite CO2 limitation of algal endosymbionts

Nils Rädecker, Claudia Pogoreutz, Christian Wild, Christian R. Voolstra*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The endosymbiosis between cnidarians and dinoflagellates of the genus Symbiodinium is key to the high productivity of tropical coral reefs. In this endosymbiosis, Symbiodinium translocate most of their photosynthates to their animal host in exchange for inorganic nutrients. Among these, carbon dioxide (CO2 ) derived fromhost respiration helps to meet the carbon requirements to sustain photosynthesis of the dinoflagellates. Nonetheless, recent studies suggest that productivity in symbiotic cnidarians such as corals is CO2 -limited. Here we show that glucose enrichment stimulates respiration and gross photosynthesis rates by 80 and 140%, respectively, in the symbiotic upside-down jellyfish Cassiopeia sp. from the Central Red Sea. Our findings show that glucose was rapidly consumed and respired within the Cassiopeia sp. holobiont. The resulting increase of CO2 availability in hospite in turn likely stimulated photosynthesis in Symbiodinium. Hence, the increase of photosynthesis under these conditions suggests that CO2 limitation of Symbiodinium is a common feature of stable cnidarian holobionts and that the stimulation of holobiont metabolism may attenuate this CO2 limitation.

Original languageEnglish (US)
Article number267
Issue numberAUG
StatePublished - Aug 15 2017

Bibliographical note

Funding Information:
The authors would like to thank Paul Müller and Zenon Batang for allocation of workspace and their assistance with the aquarium facilities at the Coastal and Marine Resources Core Lab (CMOR). We further thank the two reviewers for their constructive feedback and helpful comments., Research reported in this publication was supported by KAUST baseline funding to CRV and grant Wi 2677/9-1 awarded to CW by German Research Foundation (DFG).


  • Carbon limitation
  • Heterotrophy
  • Symbiodinium
  • Symbiosis
  • Upside-down jellyfish

ASJC Scopus subject areas

  • Oceanography
  • Global and Planetary Change
  • Aquatic Science
  • Water Science and Technology
  • Environmental Science (miscellaneous)
  • Ocean Engineering


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