Levels of ascorbic acid (vitamin C) in 11 microalgal species, across logarithmic and stationary growth phases, ranged from 1.1 (Thalassiosiru pseudonana) to 16 mg g - ’ dry weight (Chaetoceros muelleri) (Fig. 4; Brown and Miller, 1992). Levels were unrelated to algal class. Many of the species had different levels of ascorbic acid between logarithmic and stationary phases. Chaetoceros muelleri, Thalassiosira pseudonana, Nunnochloropsis oculatu and Zsochrysis sp. (T-ISO) had more ascorbic acid during the logarithmic phase, whereas Dunaliella tertiolecta and Nannochloris atomus had more ascorbic acid during the stationary phase. Despite the 15fold range in the ascorbic acid content of microalgae, all the species should provide an adequate supply of ascorbic acid to cultured animals, which are reported to require only 0.03-0.2 mg g-’ of the vitamin in their diet (Durve and Lovell, 1982; Shigueno and Itoh, 1988).
Transfer of ascorbic acid (and other vitamins) between trophic levels is important for fish larvae and late larval/early juvenile crustaceans that are reared on algal-fed zooplankton. Hapette and Poulet (1990) fed microalgae to previously starved popula-