PHYSIOLOGICAL VARIABILITY WITHIN TEN STRAINS OF CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE)

The effects of temperature, ionic composition, and conductivity on growth rates of ten strains of Chaetoceros muelleri Lemmerman (mostly var. subsalsum Johan. & Rushf.) were studied. Lipid content of stressed and unstressed cells and fatty acid composition were also determined. Considerable physiological variability was observed in the ten strains, although principal components analysis of physiological data indicated that all strains fell into one of two major groups: C. muelleri (var. muelleri and var. subsalsum ) and an undescribed Chaetoceros species morphologically close to C. muelleri var. subsalsum . A high degree of agreement was found among morphological, physiological, and biochemical data sets, indicating that physiological and biochemical data may be helpful in making taxonomic decisions in diatoms, particularly in taxa with few morphological characters.