title: LIGHT MICROSCOPE OBSERVATIONS ON CYTOLOGICAL MANIFESTATIONS OF NITRATE, PHOSPHATE, AND SILICATE DEFICIENCY IN FOUR MARINE CENTRIC DIATOMS.
abstract: Cytological changes induced by nitrate or phosphate limitation were reproducible and readily visible by phase contrast microscopy in Coscinodiscus wailesii, Ditylum brightwellii, Rhizosolenia hebetata f. semi-spina, Skeletonema costatum, and Stephanopyxis turris. These effects included changes in chromatophore number and shape, pyrenoid location, and mitochondrial abundance and appearance. In S. costatum, a diatom containing only 1 chromatophore, only nitrogen-deficient cells could be recognized. Silicate deficiency prevented cell division almost entirely. When a few cells did divide in the presence of low silicate, abnormalities in valve structure occurred in some cells. Cytological differences with N and P deficiency may permit a rough assessment of the physiological condition of the same or similar species in natural diatom communities.
authors.affiliation: Institute of Marine Resources, University of California, San Diego, La Jolla, California 92037.
authors.forename: R W
authors.initials: RW
authors.lastname: Holmes