title: Light microenvironment and single-cell gradients of carbon fixation in tissues of symbiont-bearing corals.
abstract: Recent coral optics studies have revealed the presence of steep light gradients and optical microniches in tissues of symbiont-bearing corals. Yet, it is unknown whether such resource stratification allows for physiological differences of Symbiodinium within coral tissues. Using a combination of stable isotope labelling and nanoscale secondary ion mass spectrometry, we investigated in hospite carbon fixation of individual Symbiodinium as a function of the local O2 and light microenvironment within the coral host determined with microsensors. We found that net carbon fixation rates of individual Symbiodinium cells differed on average about sixfold between upper and lower tissue layers of single coral polyps, whereas the light and O2 microenvironments differed ~15- and 2.5-fold, respectively, indicating differences in light utilisation efficiency along the light microgradient within the coral tissue. Our study suggests that the structure of coral tissues might be conceptually similar to photosynthetic biofilms, where steep physico-chemical gradients define form and function of the local microbial community.
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, New South Wales, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Wangpraseurt
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, New South Wales, Australia.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pernice
authors.affiliation: Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Guagliardo
authors.affiliation: Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Matt R
authors.initials: MR
authors.lastname: Kilburn
authors.affiliation: Centre for Microscopy, Characterisation and Analysis, The University of Western Australia, Crawley, Western Australia, Australia.|Oceans Institute, The University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Peta L
authors.initials: PL
authors.lastname: Clode
authors.affiliation: Department of Earth Sciences, Universiteit Utrecht, Utrecht, Netherlands.
authors.forename: Lubos
authors.initials: L
authors.lastname: Polerecky
authors.affiliation: Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Sydney, New South Wales, Australia.|Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Kühl
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000469:parasitology* / Q000502:physiology / Q000528:radiation effects; D002244:Carbon / Q000378:metabolism*; D057486:Carbon Cycle; D004141:Dinoflagellida / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D010788:Photosynthesis / Q000528:radiation effects; D013559:Symbiosis
chemical_list: D002244:Carbon