Measurements of diatom surface area (A) and cell volume (V) from laboratory studies, natural populations and model solids show, predictably, that discoid cells possess lower A/V ratios than tubular or ellipsoid cells of an equivalent cell volume. Estimates of plasma volume based on microscopical measurements must exhibit a similar pattern with respect to cell morphology: any estimate of plasma volume for a discoid species will contain less plasma volume per unit cell volume, than tubular or ellipsoid species. To examine whether or not a constant or variable cytoplasm thickness influences estimates of plasma volume, a comparison is made between estimates of diatom plasma volumes assuming that cytoplasm thickness is either a constant (1μm) or a variable function of cell A/V ratios. The limited number of morphometric observations from the literature show that there is insufficient data to choose between the assumption that diatom cytoplasm is constant or variable; this is most evident in larger diatoms. Future studies are needed to compare morphometric estimates of plasma volume with cell constituents to determine if a relationship exists.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science