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The Influence of the Mineral Composition of the Medium on the Growth of Planktonic Algae: Part I. Methods and Culture Media

S. P. Chu
Journal of Ecology
Vol. 30, No. 2 (Aug., 1942), pp. 284-325
DOI: 10.2307/2256574
Stable URL: http://www.jstor.org/stable/2256574
Page Count: 42
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
The Influence of the Mineral Composition of the Medium on the Growth of Planktonic Algae: Part I. Methods and Culture Media
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Abstract

1. Suitable media for the growth of various plankton algae have been prepared using pure chemicals, the formulae being based on the results of series of experiments and on the analyses of fresh waters. In composition and degree of dilution they are comparable with ordinary natural waters, so that experimental results obtained with them should be applicable to natural conditions. Fourteen planktonic algae, isolated from various localities, have been maintained in these solutions in unialgal culture in a flourishing condition for more than two years and could no doubt be cultured indefinitely. 2. The suitable ranges of important salts, liable to change in natural waters, have been determined for the growth of different planktonic algae and the effect on their development discussed. 3. With few exceptions (e.g. Botryococcus, which grows better with nitrate N), the planktonic algae investigated grow equally well in media supplied with nitrate and in those supplied with ammonium salts as long as the N concentration is within the optimum range, but in lower N concentrations growth is generally better when nitrate is supplied. 4. The most favourable concentrations of Ca, Mg, K, Na and SiO2 differ considerably for different algae. Thus Pediastrum Boryanum favours low concentrations of Ca, Mg, and SiO2, but comparatively higher concentrations of K; diatoms favour high concentrations of Ca, Mg and SiO2, and lower concentrations of K; while Botryococcus has great tolerance for high Na concentrations. 5. The Ca requirement is often lower in media with higher Mg concentrations, while the presence of excessive K renders the organisms tolerant of higher concentrations of Ca and Mg. 6. No appreciable quantity of SiO2 is necessary for the growth of planktonic algae, with the exception of diatoms. There is an unfavourable effect on the growth of Pediastrum when the SiO2 concentration exceeds 4 p.p.m. and on Staurastrum paradoxum and Botryococcus when it is more than 20 p.p.m. The inhibiting effect is marked, even on diatoms, when the concentration is more than 54 p.p.m. 7. The requirements of N and P agree well among the different planktonic algae, in contrast to the requirements of Ca, Mg, K, Na and SiO2, though there are minor differences in the lower and upper limits that are suitable. All the algae studied flourish in media with N 1-7, and P 0.1-2 p.p.m., and are likely to suffer from a deficiency when the concentration of N is below 0.2 and that of P below 0.05, and from an inhibiting effect when the concentrations of N and P exceed 20 p.p.m. 8. The optimum range of P concentration is often wider when nitrate is used than when an ammonium salt is used as a source of N.

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