FLUCTUATIONS IN ALGAL CHLOROPHYLL AND CAROTENOID-PIGMENTS DURING SOLAR BLEACHING IN THE CORAL GONIASTREA-ASPERA AT PHUKET, THAILAND

HPLC analysis of pigments of the symbiotic algae of the coral Goniastr ea aspera (Verrill) showed the presence of the chlorophylls a and c(2) (chl a and c(2)) and the carotenoids peridinin, diadinoxanthin, diato xanthin and beta-carotene. Increased production of diatoxanthin was se en in algae extracted from the western surfaces of corals, exposed to high levels of solar radiation, during a solar bleaching event. In add ition, an increase in the ratio of diatoxanthin to the total xanthophy ll pool was observed in bleached tissues, together with a progressive increase in the total xanthophyll pool (relative to total chlorophyll levels) over the bleaching period. These results support a potential p hotoprotective function for xanthophylls in the coral/algal symbiosis. Chlorophyll breakdown products, phaeophytin a and pyrophaeophytin a, were recognised in considerable quantities only in bleached tissues. C omputation of a simple chlorophyll budget showed that 45% of chl a was lost in partially bleached tissues and approximately 62% in fully ble ached tissues, indicating a very rapid photodegradation of chlorophyll 24 h after exposure to high irradiance.