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Skeletal light-scattering accelerates bleaching response in reef-building corals.
BMC Ecol. 2016 Mar 21; 16:10.BE

Abstract

BACKGROUND

At the forefront of ecosystems adversely affected by climate change, coral reefs are sensitive to anomalously high temperatures which disassociate (bleaching) photosynthetic symbionts (Symbiodinium) from coral hosts and cause increasingly frequent and severe mass mortality events. Susceptibility to bleaching and mortality is variable among corals, and is determined by unknown proportions of environmental history and the synergy of Symbiodinium- and coral-specific properties. Symbiodinium live within host tissues overlaying the coral skeleton, which increases light availability through multiple light-scattering, forming one of the most efficient biological collectors of solar radiation. Light-transport in the upper ~200 μm layer of corals skeletons (measured as 'microscopic' reduced-scattering coefficient, μ'(S,m)), has been identified as a determinant of excess light increase during bleaching and is therefore a potential determinant of the differential rate and severity of bleaching response among coral species.

RESULTS

Here we experimentally demonstrate (in ten coral species) that, under thermal stress alone or combined thermal and light stress, low-μ'(S,m) corals bleach at higher rate and severity than high-μ'(S,m) corals and the Symbiodinium associated with low-μ'(S,m) corals experience twice the decrease in photochemical efficiency. We further modelled the light absorbed by Symbiodinium due to skeletal-scattering and show that the estimated skeleton-dependent light absorbed by Symbiodinium (per unit of photosynthetic pigment) and the temporal rate of increase in absorbed light during bleaching are several fold higher in low-μ'(S,m) corals.

CONCLUSIONS

While symbionts associated with low-[Formula: see text] corals receive less total light from the skeleton, they experience a higher rate of light increase once bleaching is initiated and absorbing bodies are lost; further precipitating the bleaching response. Because microscopic skeletal light-scattering is a robust predictor of light-dependent bleaching among the corals assessed here, this work establishes μ'(S,m) as one of the key determinants of differential bleaching response.

Authors+Show Affiliations

Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA. Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA. Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA. Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA. Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Keck Biophysics Facility, Northwestern University, 633 Clark Street, Evanston, IL, 60208, USA.Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA.Fishes Department, John G. Shedd Aquarium, 1200 South Lake Shore Drive, Chicago, IL, 60605, USA.Fishes Department, John G. Shedd Aquarium, 1200 South Lake Shore Drive, Chicago, IL, 60605, USA.Fishes Department, John G. Shedd Aquarium, 1200 South Lake Shore Drive, Chicago, IL, 60605, USA.Fishes Department, John G. Shedd Aquarium, 1200 South Lake Shore Drive, Chicago, IL, 60605, USA.Division of Water Resource Management, Florida Department of Environmental Protection, 2600 Blair Stone Road, Tallahassee, 32399, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.Department of Civil and Environmental Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA. l-marcelino@northwestern.edu. Department of Zoology, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL, 60605, USA. l-marcelino@northwestern.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

26996922

Citation

Swain, Timothy D., et al. "Skeletal Light-scattering Accelerates Bleaching Response in Reef-building Corals." BMC Ecology, vol. 16, 2016, p. 10.
Swain TD, DuBois E, Gomes A, et al. Skeletal light-scattering accelerates bleaching response in reef-building corals. BMC Ecol. 2016;16:10.
Swain, T. D., DuBois, E., Gomes, A., Stoyneva, V. P., Radosevich, A. J., Henss, J., Wagner, M. E., Derbas, J., Grooms, H. W., Velazquez, E. M., Traub, J., Kennedy, B. J., Grigorescu, A. A., Westneat, M. W., Sanborn, K., Levine, S., Schick, M., Parsons, G., Biggs, B. C., ... Marcelino, L. A. (2016). Skeletal light-scattering accelerates bleaching response in reef-building corals. BMC Ecology, 16, 10. https://doi.org/10.1186/s12898-016-0061-4
Swain TD, et al. Skeletal Light-scattering Accelerates Bleaching Response in Reef-building Corals. BMC Ecol. 2016 Mar 21;16:10. PubMed PMID: 26996922.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Skeletal light-scattering accelerates bleaching response in reef-building corals. AU - Swain,Timothy D, AU - DuBois,Emily, AU - Gomes,Andrew, AU - Stoyneva,Valentina P, AU - Radosevich,Andrew J, AU - Henss,Jillian, AU - Wagner,Michelle E, AU - Derbas,Justin, AU - Grooms,Hannah W, AU - Velazquez,Elizabeth M, AU - Traub,Joshua, AU - Kennedy,Brian J, AU - Grigorescu,Arabela A, AU - Westneat,Mark W, AU - Sanborn,Kevin, AU - Levine,Shoshana, AU - Schick,Mark, AU - Parsons,George, AU - Biggs,Brendan C, AU - Rogers,Jeremy D, AU - Backman,Vadim, AU - Marcelino,Luisa A, Y1 - 2016/03/21/ PY - 2015/08/19/received PY - 2016/02/12/accepted PY - 2016/3/22/entrez PY - 2016/3/22/pubmed PY - 2016/9/13/medline KW - Coral bleaching KW - Global climate change KW - Optical scattering KW - Photosynthesis KW - Symbiosis SP - 10 EP - 10 JF - BMC ecology JO - BMC Ecol VL - 16 N2 - BACKGROUND: At the forefront of ecosystems adversely affected by climate change, coral reefs are sensitive to anomalously high temperatures which disassociate (bleaching) photosynthetic symbionts (Symbiodinium) from coral hosts and cause increasingly frequent and severe mass mortality events. Susceptibility to bleaching and mortality is variable among corals, and is determined by unknown proportions of environmental history and the synergy of Symbiodinium- and coral-specific properties. Symbiodinium live within host tissues overlaying the coral skeleton, which increases light availability through multiple light-scattering, forming one of the most efficient biological collectors of solar radiation. Light-transport in the upper ~200 μm layer of corals skeletons (measured as 'microscopic' reduced-scattering coefficient, μ'(S,m)), has been identified as a determinant of excess light increase during bleaching and is therefore a potential determinant of the differential rate and severity of bleaching response among coral species. RESULTS: Here we experimentally demonstrate (in ten coral species) that, under thermal stress alone or combined thermal and light stress, low-μ'(S,m) corals bleach at higher rate and severity than high-μ'(S,m) corals and the Symbiodinium associated with low-μ'(S,m) corals experience twice the decrease in photochemical efficiency. We further modelled the light absorbed by Symbiodinium due to skeletal-scattering and show that the estimated skeleton-dependent light absorbed by Symbiodinium (per unit of photosynthetic pigment) and the temporal rate of increase in absorbed light during bleaching are several fold higher in low-μ'(S,m) corals. CONCLUSIONS: While symbionts associated with low-[Formula: see text] corals receive less total light from the skeleton, they experience a higher rate of light increase once bleaching is initiated and absorbing bodies are lost; further precipitating the bleaching response. Because microscopic skeletal light-scattering is a robust predictor of light-dependent bleaching among the corals assessed here, this work establishes μ'(S,m) as one of the key determinants of differential bleaching response. SN - 1472-6785 UR - https://www.unboundmedicine.com/medline/citation/26996922/Skeletal_light_scattering_accelerates_bleaching_response_in_reef_building_corals_ L2 - https://bmcecol.biomedcentral.com/articles/10.1186/s12898-016-0061-4 DB - PRIME DP - Unbound Medicine ER -