Elemental components of cyst walls of three marine phytofiagellates, Chattonella antiqua (Raphidophyceae), Alexandrium catenella and Scrippsiella trochoidea (Dinophyceae)

Abstract

The marine phytoftagellates Chattonella antiqua (Hada) Ono, Alexandrium catenella (Whedon et Kofoid) Balech and Scrippsiella trochoidea (Stein) Loeblich III were induced to form cysts under laboratory conditions. The elemental composition of the cyst walls before and after treatment with concentrated H2SO4 was examined by energy dispersive X-ray analysis (EDX). In all three species the cyst wall was resistant to some extent to H2SO4. EDX analysis demonstrated that the principal components 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 cyst walls of A. catenella and S. trochoidea. In all species, the relative 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 although cyst walls can resist concentrated H2SO4, part of the wall is dissolved 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.