Corals as light collectors: an integrating sphere approach

Stambler, Noga; Dubinsky, Zvy

doi:10.1007/s00338-004-0452-4

Cited by 96 publications

(100 citation statements)

References 64 publications

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“…Although the absorption properties of the symbionts and the specific absorption of Chl a have been measured for suspensions of freshly isolated dinoflagellates (coral ''blastates'') (Dubinsky et al 1984Wyman et al 1987;Lesser et al 2000), the assessment of the optical properties of intact corals from such data is, at best, unclear. In a recent paper, Stambler and Dubinsky (2005) have reported absorption measurements of intact corals using an integrating sphere; we note, however, that their results and conclusions differ from those presented here.…”

Section: Acknowledgmentscontrasting

confidence: 95%

Multiple scattering on coral skeletons enhances light absorption by symbiotic algae

Mendez²,

2005

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The success of symbiotic reef-building corals is largely determined by the efficiency with which they collect solar energy. Using thin coral laminae from the Caribbean scleractinian Porites branneri, we characterize the absorption spectra of intact coral surfaces. Comparisons of absorption spectra from corals with a broad range of photosynthetic pigment densities, collected during a natural bleaching event, indicate that they are capable of collecting more than 85% of solar radiation with one order of magnitude less pigment density than terrestrial leaves. Measurements of the light-absorption efficiency as a function of pigment density reveal that symbiotic algae in intact P. branneri absorb between two and five times more light than freshly isolated symbionts. A theoretical model shows that multiple scattering by the skeleton can enhance the local light field, thus increasing absorption. As a result of this phenomenon, corals inhabiting high light environments can maximize their absorption capacity with low pigment investment while reducing self-shading in low-light environments. Local light field enhancements may have negative effects when corals are exposed to stressful conditions. During coral bleaching, increases in local irradiance associated with reductions in pigment density could exacerbate the negative effect of elevated temperatures. Symbiotic scleractinian corals are one of the most efficient solar energy collectors in nature, and the modulation of the internal light field by the coral skeleton may be an important driving force in the evolution of this group.

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Section: Acknowledgmentscontrasting

confidence: 95%

Multiple scattering on coral skeletons enhances light absorption by symbiotic algae

Mendez²,

2005

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“…These results are consistent with photosynthetic action-spectra measured with fluorescence (Lesser et al 2000;) and oxygen sensors (Kuhl et al 1995) where the intensity parameter is the incident irradiance. This effect results from strong scattering and pigment-packaging occurring at the level of the symbionts inside the coral tissue (Kirk 1994;Stambler and Dubinsky 2005). As a result, the contribution of wavelengths outside the major pigment absorption bands to the excitation of the symbionts' chlorophyll fluorescence is substantial.…”

Section: Discussionmentioning

confidence: 99%

Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellae

et al. 2013

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Green fluorescent protein (GFP)-like pigments are responsible for the vivid colouration of many reefbuilding corals and have been proposed to act as photoprotectants. Their role remains controversial because the functional mechanism has not been elucidated. We provide direct evidence to support a photoprotective role of the non-fluorescent chromoproteins (CPs) that form a biochemically and photophysically distinct group of GFP-like proteins. Based on observations of Acropora nobilis from the Great Barrier Reef, we explored the photoprotective role of CPs by analysing five coral species under controlled conditions. In vitro and in hospite analyses of chlorophyll excitation demonstrate that screening by CPs leads to a reduction in chlorophyll excitation corresponding to the spectral properties of the specific CPs present in the coral tissues. Between 562 and 586 nm, the CPs maximal absorption range, there was an up to 50 % reduction of chlorophyll excitation. The screening was consistent for established and regenerating tissue and amongst symbiont clades A, C and D. Moreover, among two differently pigmented morphs of Acropora valida grown under identical light conditions and hosting subclade type C3 symbionts, high CP expression correlated with reduced photodamage under acute light stress.

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“…Although the results and conclusions of the two studies differ, the calculated light collection efficiencies for the symbiont pigments are significantly higher than those obtained using freshly isolated dinoflagellates. Stambler and Dubinsky (2005) used an integrating sphere to determine the fraction of the incident radiation captured by the symbiotic dinoflagellates of several corals species, whereas Enríquez and coworkers (2005) used thin laminae of Porites branneri and the opal glass technique (Shibata 1959) to determine, in transmission mode, the absorption properties of the symbionts. Unfortunately, the preparation of thin lamina can be used in only a limited set of coral species.…”

Section: Discussionmentioning

confidence: 99%

Photosynthesis and light utilization in the Caribbean coral Montastraea faveolata recovering from a bleaching event

Rodríguez-Román

Hernández-Pech

Thomé

et al. 2006

Limnology & Oceanography

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Coral bleaching-the loss of symbiotic dinoflagellates-is initiated when corals are exposed to sea surface temperatures above the regional summer average and has been responsible for massive coral mortality episodes. The ability of symbionts to recolonize the host after bleaching may be critical in determining if a colony will recover or experience mortality. Here, following the serendipitous bleaching of specimens of Montastraea faveolata of known photosynthetic, spectroscopic, and genetic characteristics, we describe changes in photosynthesis and light utilization during the recovery process. Fully recovered M. faveolata had minimum quantum requirements (1/W max ) that are very close to the theoretical minimum, indicating that symbiotic corals are not only one of the most efficient light collectors in nature, but also use this energy with maximum efficiency. Analyses of the photosynthetic responses of M. faveolata throughout the recovery process indicate that during the early stages, the symbiont population exhibited characteristics consistent with acclimation to higher irradiance relative to fully recovered corals. The absorption spectra of bleached samples showed contributions of chlorophyll b (Chl b) associated with a biomass increase of the endolithic algae. The propagation of endolithic algae after bleaching may provide partial protection to the surviving symbionts from excessive radiation by reducing the reflectivity of the skeleton. Changes in the relative abundances of different symbiotic algae between recovered and unbleached colonies did not result in significant variations in photosynthetic and light utilization characteristics.

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Corals as light collectors: an integrating sphere approach

Cited by 96 publications

References 64 publications

Multiple scattering on coral skeletons enhances light absorption by symbiotic algae

Multiple scattering on coral skeletons enhances light absorption by symbiotic algae

Screening by coral green fluorescent protein (GFP)-like chromoproteins supports a role in photoprotection of zooxanthellae

Photosynthesis and light utilization in the Caribbean coral Montastraea faveolata recovering from a bleaching event

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