White but not bleached: photophysiological evidence from white Montastraea cavernosa reveals potential overestimation of coral bleaching

• Published in: Marine biology Vol. 162; no. 4; pp. 889 - 899
• Main Authors: Cruz, Igor C. S., Leal, Miguel C., Mendes, Carlos R., Kikuchi, Ruy K. P., Rosa, Rui, Soares, Amadeu M. V. M., Serôdio, João, Calado, Ricardo, Rocha, Rui J. M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2015; Springer; Springer Nature B.V
• Subjects: Abiotic stress; Biomedical and Life Sciences; Climate change; Coral bleaching; Coral reefs; Corals; Environmental stress; Freshwater & Marine Ecology; Life Sciences; Marine & Freshwater Sciences; Marine biology; Microbiology; Montastraea cavernosa; Observations; Oceanography; Original Paper; Photobiology; Photosynthesis; Physiological aspects; Symbiodinium; Symbiosis; Zoology; Brazil; ASW, Brazil, Bahia, Todos os Santos Bay; ASW, Brazil; White Coloni; Coral Bleaching; Video Transect; Normalize Difference Vegetation Index; Photosynthetic Pigment
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-015-2633-9

Climate change and other types of environmental stress are known to increase corals’ vulnerability to bleaching, a process whereby colonies lose their colour either due to the loss of photosynthetic symbionts or their pigments. Although bleaching leaves the coral skeleton visible under its transparent tissue, not all white coral colonies display this feature. This raises the question as to whether all ‘white’-shaded colonies are indeed bleached. Within this context,
Montastraea cavernosa
colonies of different colour types (dark brown, light brown, bleached and white) were sampled for photobiological evaluation. Here, we show that, while the conventional spectral reflectance techniques failed to discriminate white from bleached colonies, chlorophyll fluorescence, photosynthetic pigment profile and
Symbiodinium
density enabled a clear distinction between these shades. Subsequently, video transects from reef monitoring surveys at Todos os Santos Bay (Brazil) revealed that the proportion of bleached and white colonies is similar, thus suggesting that current coral reef surveys may be overestimating the bleaching of
M. cavernosa
by nearly twofold.