SIZE DEPENDENCE OF GROWTH RATE, RESPIRATORY ELECTRON TRANSPORT SYSTEM ACTIVITY, AND CHEMICAL COMPOSITION IN MARINE DIATOMS IN THE LABORATORY¹

Abstract

The dependence of growth, electron transport system activity and chemical composition on the size of diatoms was examined during the exponential phase of growth. The six different marine centric species compared ranged in volume from 7.7 μm3 to 62 × 105μm3. A size dependence was observed for growth, 14C uptake, respiration and the productivity index (14C/chl a). Although the size dependence of all parameters was similar, the results indicate that on a carbon basis, growth efficiency decreases with increasing size. The C/N and C/chl a ratios were not size dependent. The importance of the surface area to cell volume ratio, and the importance of carbon per unit volume in determining the observed size dependence are discussed.

Maximal growth rates of Antarctic phytoplankton: Only weak dependence on cell size

“…In summary, the data presented here support the conclusions of Banse (1982) and Blasco et al (1982) that marine diatoms show only a weak size dependence on maximal growth rates. Peters' claim that all specific metabolic rates should decline with the -0.25th power of body size is not supported.…”

“…2. A similar equation by Blasco et al (1982) is not discussed here, because it is almost identical with Banse's.…”

Size dependence of growth and photosynthesis in diatoms: a synthesis

“…The maximum growth rate of diatoms ranges from about 3 d-I (3.5 X 10-5 S-') for cells of under 100 pm3 volume to under 1 d-' (1.1 X 10-5 S-') for cells of about 106 pm3 volume at about 20 "C (Banse 1982a, Blasco et al 1982. The size dependence of nutrient-sufficient maximum growth rates is well documented in the diatoms (Fig.…”

“…All observations are for cells cultured under continuous illumination at a temperature between 18 and 22°C suggest that there is little interspecific variability, but a pronounced PFD dependence. Comparisons of the chlorophyll a : carbon ratio in diatoms (Taguchi 1976, Durbin 1977, Blasco et al 1982) and chlorophytes ) cultured under the same environmental conditions indicate that this ratio is independent of cell size. Consistent with this conclusion are observations that cell chlorophyll a, protein, lipid and carbohydrate contents have the same size dependence in both diatoms and dinoflagellates (Chan 1978, Hitchcock 1982.…”

“…A reduction in cell division rate with increased size is documented in microalgae (Banse 1976, Blasco et al 1982, although the magnitude of the exponent has been the subject of some discussion (Chan 1978, Banse 1982a. In particular, it appears that size dependence of metabolic rates only become statistically significant when organisms from a large range of sizes are considered a n d when care is taken to discriminate among metabolic and/or taxonomic types.…”