LIGHT TRANSMISSION AND SPECTRAL DISTRIBUTION THROUGH EPI- AND ENDOZOIC ALGAL LAYERS IN THE BRAIN CORAL, FAVIA

¹ The Tokugawa Institute for Biological Research, Mejiromachi, Tokyo
² Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 90237

Two species of algae are living symbiotically with a hard brain coral, Favia pallida; a brown alga resembling Symbiodinium microadriaticum Freudenthal as a brown surface layer and green algae, most of them probably belonging to Ostrebium Reineckei Bornet, as a green layer with an intermediate white layer between them. The in vivo absorption spectra of these algal layers were observed with a new spectrophotometer suitable for the measurements of translucent dark pieces of corals, and light transmission through these layers of algae and its spectral distribution were calculated from the spectra. The spectrum of the top brown layer showed the band characteristics of dinoflagellates, and the in vivo bands of chlorophylls a and c and peridinin were identified. The bands of chlorophyll c and peridinin were also found in the fluorescence action spectrum which indicates energy transfer from these pigments to chlorophyll a. The spectrum of the third layer showed the band characteristics of green algae, and the light intensity and spectral distribution after transmission through the brown and the intermediate layers were found to be suitable for the green alga on the top of the green layer to bring about photosynthesis actively. On the other hand, the light intensity in the middle or at the bottom of the green layer was very low, being consistent with the fact that the pigments of the cells in these deep areas are easily photooxidized.

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