title: IMPORTANCE OF MACRO- VERSUS MICROSTRUCTURE IN MODULATING LIGHT LEVELS INSIDE CORAL COLONIES(1).
abstract: Adjusting the light exposure and capture of their symbiotic photosynthetic dinoflagellates (genus Symbiodinium Freud.) is central to the success of reef-building corals (order Scleractinia) across high spatio-temporal variation in the light environment of coral reefs. We tested the hypothesis that optical properties of tissues in some coral species can provide light management at the tissue scale comparable to light modulation by colony architecture in other species. We compared within-tissue scalar irradiance in two coral species from the same light habitat but with contrasting colony growth forms: branching Stylophora pistillata and massive Lobophyllia corymbosa. Scalar irradiance at the level of the symbionts (2 mm into the coral tissues) were <10% of ambient irradiance and nearly identical for the two species, despite substantially different light environments at the tissue surface. In S. pistillata, light attenuation (90% relative to ambient) was observed predominantly at the colony level as a result of branch-to-branch self-shading, while in L. corymbosa, near-complete light attenuation (97% relative to ambient) was occurring due to tissue optical properties. The latter could be explained partly by differences in photosynthetic pigment content in the symbiont cells and pigmentation in the coral host tissue. Our results demonstrate that different strategies of light modulation at colony, polyp, and cellular levels by contrasting morphologies are equally effective in achieving favorable irradiances at the level of coral photosymbionts.
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Paulina
authors.initials: P
authors.lastname: Kaniewska
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Sveinn H
authors.initials: SH
authors.lastname: Magnusson
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Kenneth R N
authors.initials: KR
authors.lastname: Anthony
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Ruth
authors.initials: R
authors.lastname: Reef
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Kühl
authors.affiliation: ARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaMarine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, DenmarkARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, AustraliaSchool of Biological Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia Marine Biological Laboratory, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, PO Box 123, Ultimo Sydney, New South Wales 2007, AustraliaARC Centre of Excellence, Global Change Institute, The University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: Ove
authors.initials: O
authors.lastname: Hoegh-Guldberg
keywords: Symbiodinium; irradiance; morphology; photoacclimation; scale; scleractinian coral