Chapter 13 



Fission Rate of Plankton Algae of 

 the Black Sea in Cultures 



L. A. Lanskaya 



Xlie present material is the result of the observations of 

 many years, done, at first, under the leadership of Prof. Morozova- 

 Vodjanitskaja. It describes the division rate in culture, of species 

 of plankton algae blooming in the Black Sea. These data can 

 sei've as initial material for judging the rate of renewal and dying 

 off of phytoplankton in the sea, the potential productivity of 

 each of the examined species, and also grazing by consumers. 



The algae were grown on filtered sea water enriched with 

 the components of the "Erdschreiber" and a modified Allen- 

 Nelson solution. The cultures were grown in a box under natural 

 light (about 1000 lux in winter to 3800 lux in summer). The 

 temperature of water in the experimental vessels with algae was 

 usually higher than in the sea: 1-2 C in summer and autumn, 

 and 5-6 C in winter and spring-time. 



Unialgal cultures were obtained by picking cells or chains 

 directly from a plankton-net sample. Mixed cultures were ob- 

 tained by inoculation of a certain volume of water taken with 

 a bathometer. 



In most cases the division rate of planktonic algae was 

 studied in cultures reared from several cells. The experiments 

 lasted usually five to seven days, as the overgrowth of the cul- 

 ture markedly influences the division rate of cells. 



Tlie division rate of the algae at different periods of a year 

 was determined two to three times a month. The diumal rhythm 

 of the division rate of cells was also determined. Eveiy observa- 

 tion was carried out with a fresli culture, even though many 

 seasonally occurring algae grew well in cultures for five to six 

 months, and year-long forms can be grown for several years. 



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