Autecology, pigment composition and toxicology ofDictyocha octonaria(Dictyochophyceae, Ochrophyta) from Wellington Harbor, New Zealand

Summary Growth and pigment composition of both the skeleton-bearing and naked forms and toxicology of the naked form of Dictyocha octonaria were studied here using clonal cultures derived from a single cell from Wellington Harbour. In this study both the naked and skeleton-bearing forms showed optimum growth between 14 and 18°C. Maximum growth rates of the naked and skeleton-bearing forms were 1.46 and 0.99 division day−1, respectively. Growth rates of the naked form at temperatures 22°C. Cells of the naked form died at 24°C while those of the skeleton-bearing form at 26°C. In this study the naked and skeleton-bearing forms cultured in identical growth conditions contained almost the same pigments, except zeaxanthin, which made up about 3.2% of the total carotenoid in the skeleton-bearing form and virtually none in the naked form. Toxicological tests conducted on rotifers indicated that the naked form was not harmful to the test organisms.