ELEMENTAL COMPONENTS OF CYST WALLS OF 3 MARINE PHYTOFLAGELLATES, CHATTONELLA-ANTIQUA (RAPHIDOPHYCEAE), ALEXANDRIUM-CATENELLA AND SCRIPPSIELLA-TROCHOIDEA (DINOPHYCEAE)

The marine phytoflagellates Chattonella antiqua (Hada) Ono, Alexandriu m catenella (Whedon et Kofoid) Balech and Scrippsiella trochoidea (Ste in) Loeblich Ill were induced to form cysts under laboratory condition s. The elemental composition of the cyst walls before and after treatm ent with concentrated H2SO4, was examined by energy dispersive X-ray a nalysis (EDX). In all three species the cyst wall was resistant to som e extent to H2SO4. EDX analysis demonstrated that the principal compon ents of the cyst walls were silicon (Si), magnesium (Mg) and aluminium (Al). The crystalline spines of S. trochoidea cysts contained mainly calcium (Ca). A high relative abundance of sulphur (S) was found in cy st walls of A. catenella and S. trochoidea. In all species, the relati ve concentration of Mg and Al in the cyst walls decreased after H2SO4 treatment, whereas the relative concentration of Si increased markedly . The relative concentration of S in cyst walls of A. catenella and S. trochoidea also decreased after acid treatment. This suggests that al though cyst walls can resist concentrated H2SO4, part of the wall is d issolved in the acid. Following acid treatment Si was the predominant element in cyst walls of all three species and the resistance to acid may be associated with the presence of Si.