PHOTOSYNTHETIC PIGMENTS OF SYMBIOTIC DINOFLAGELLATES (ZOOXANTHELLAE) FROM CORALS AND CLAMS

¹ CSIRO Marine Laboratory, Cronulla, Sydney 2230, Australia
² Scripps Institution of Oceanography, La Jolla, California

1. The photosynthetic pigments of the brown symbiotic algae (zooxanthellae) isolated from five tridacnid clams and nine corals were found to be identical with the pigments of the dinoflagellate Amphidinium. Identifications were carried out by two-dimensional paper chromatography and by absorption spectrophotometry. Both zooxanthellae and dinoflagellates contained cholorphylls a and c, -carotene, peridinin, neo-peridinin, dinoxanthin, neo-dinoxanthin, diadinoxanthin, and three minor xanthophyll fractions not previously described.

2. Peridinin, crystallized from Tridacna gigas, or isolated by paper chromatography from Tridacna crocea, Pocillopora or the dinoflagellate Amphidinium, showed similar absorption characteristics in different solvents. The extinction coefficient of crystalline peridinin in acetone was E_{1 cm}^1% 1340.

3. Clam zooxanthellae (and the dinoflagellates Amphidinium and Gymnodinium) contained a much higher proportion of chlorophyll c than coral zooxanthellae.

4. No chlorophyll decomposition products were found in any freshly prepared zooxanthellae preparations.