STEROLS OF CHAETOCEROS AND SKELETONEMA

Dietary sterol is required by the oyster for growth, and sterol is bel ieved to be obtained primarily from dietary phytoplankton. Seven isola tes of Chaetoceros and one of Skeletonema, which are of potential use as oyster food, were analyzed for sterol composition using gas chromat ography, high-performance liquid chromatography and gas chromatography /mass spectrometry. Skeletonema and five isolates of Chaetoceros conta ined cholesterol as their major sterol. Two other isolates of Chaetoce ros also contained cholesterol, but 24-methylenecholesterol was the pr incipal sterol. Cholesterol has rarely been reported as the major ster ol from phytoplankton. In view of the widespread occurrence of Skeleto nema and Chaetoceros in the marine environment, these algae could be a n important source of the oyster's cholesterol.