Red Light Represses the Photophysiology of the Scleractinian Coral Stylophora pistillata
2014
Wijgerde, T.H.M. | Melis, A.A.M. | Ferreira Da Silva, C.I. | Leal, M.C. | Vogels, L. | Mutter, C. | Osinga, R.
Light spectrum plays a key role in the biology of symbiotic corals, with blue light resulting in higher coral growth, zooxanthellae density, chlorophyll a content and photosynthesis rates as compared to red light. However, it is still unclear whether these physiological processes are blue-enhanced or red-repressed. This study investigated the individual and combined effects of blue and red light on the health, zooxanthellae density, photophysiology and colouration of the scleractinian coral Stylophora pistillata over 6 weeks. Coral fragments were exposed to blue, red, and combined 50/50% blue red light, at two irradiance levels (128 and 256 µmol m-2 s-1). Light spectrum affected the health/survival, zooxanthellae density, and NDVI (a proxy for chlorophyll a content) of S. pistillata. Blue light resulted in highest survival rates, whereas red light resulted in low survival at 256 µmol m-2 s-1. Blue light also resulted in higher zooxanthellae densities compared to red light at 256 µmol m-2 s-1, and a higher NDVI compared to red and combined blue red light. Overall, our results suggest that red light negatively affects the health, survival, symbiont density and NDVI of S. pistillata, with a dominance of red over blue light for NDVI.
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