TY - JOUR

T1 - The importance of macro- versus microstructure in modulating light levels inside coral colonies

AU - Kaniewska, Paulina

AU - Magnusson, Sveinn H.

AU - Anthony, Ken R. N.

AU - Reef, Ruth

AU - Kühl, Michael

AU - Hoegh-Guldberg, Ove

PY - 2011

Y1 - 2011

N2 - Adjusting the light exposure and capture of theirsymbiotic photosynthetic dinoflagellates (genusSymbiodinium Freud.) is central to the success ofreef-building corals (order Scleractinia) across highspatio-temporal variation in the light environment ofcoral reefs. We tested the hypothesis that opticalproperties of tissues in some coral species can providelight management at the tissue scale comparableto light modulation by colony architecture inother species. We compared within-tissue scalar irradiancein two coral species from the same light habitatbut with contrasting colony growth forms:branching Stylophora pistillata and massive Lobophylliacorymbosa. Scalar irradiance at the level of the symbionts(2 mm into the coral tissues) were <10% ofambient irradiance and nearly identical for the twospecies, despite substantially different light environmentsat the tissue surface. In S. pistillata, lightattenuation (90% relative to ambient) was observedpredominantly at the colony level as a result ofbranch-to-branch self-shading, while in L. corymbosa,near-complete light attenuation (97% relative toambient) was occurring due to tissue optical properties.The latter could be explained partly by differencesin photosynthetic pigment content in thesymbiont cells and pigmentation in the coral hosttissue. Our results demonstrate that differentstrategies of light modulation at colony, polyp, andcellular levels by contrasting morphologies areequally effective in achieving favorable irradiancesat the level of coral photosymbionts.Key index words: irradiance; morphology; photoacclimation;scale; scleractinian coral; SymbiodiniumAbbreviations: achl a, specific absorption coefficientof chl a; Ddn, diadinoxanthin; Dtn, diatoxanthin;GBR, Great Barrier Reef; GFP, green fluorescentprotein; Kd, light attenuation coefficient of downwellingirradiance

AB - Adjusting the light exposure and capture of theirsymbiotic photosynthetic dinoflagellates (genusSymbiodinium Freud.) is central to the success ofreef-building corals (order Scleractinia) across highspatio-temporal variation in the light environment ofcoral reefs. We tested the hypothesis that opticalproperties of tissues in some coral species can providelight management at the tissue scale comparableto light modulation by colony architecture inother species. We compared within-tissue scalar irradiancein two coral species from the same light habitatbut with contrasting colony growth forms:branching Stylophora pistillata and massive Lobophylliacorymbosa. Scalar irradiance at the level of the symbionts(2 mm into the coral tissues) were <10% ofambient irradiance and nearly identical for the twospecies, despite substantially different light environmentsat the tissue surface. In S. pistillata, lightattenuation (90% relative to ambient) was observedpredominantly at the colony level as a result ofbranch-to-branch self-shading, while in L. corymbosa,near-complete light attenuation (97% relative toambient) was occurring due to tissue optical properties.The latter could be explained partly by differencesin photosynthetic pigment content in thesymbiont cells and pigmentation in the coral hosttissue. Our results demonstrate that differentstrategies of light modulation at colony, polyp, andcellular levels by contrasting morphologies areequally effective in achieving favorable irradiancesat the level of coral photosymbionts.Key index words: irradiance; morphology; photoacclimation;scale; scleractinian coral; SymbiodiniumAbbreviations: achl a, specific absorption coefficientof chl a; Ddn, diadinoxanthin; Dtn, diatoxanthin;GBR, Great Barrier Reef; GFP, green fluorescentprotein; Kd, light attenuation coefficient of downwellingirradiance

U2 - 10.1111/j.1529-8817.2011.01021.x

DO - 10.1111/j.1529-8817.2011.01021.x

M3 - Journal article

C2 - 27020021

VL - 47

SP - 846

EP - 860

JO - Journal of Phycology

JF - Journal of Phycology

SN - 0022-3646

IS - 4

ER -