engleski

The assessment of nutrient availability for the growth of freshwater green algae Chlorella kessleri by bioassay (Lake Sakadaš, NP Kopački Rit)

The influence of nutrient availability on the growth of Chlorella kessleri was investigated in water samples of Lake Sakadaš, from March to September 2005. A nutrient enrichment bioassay was performed to test nitrogen and phosphorus limitation of freshwater green algae C. kessleri. A statistically significant correlation (r = 0.964, P<0.01) was established between the total biomass of C. kessleri in original water samples and nitrate concentration in situ. In the nutrient enrichment bioassay, only the addition of nitrogen showed a statistically significant influence on the growth rate of C. kessleri. In order to quantify the established nutrient limitation, the effect of N (in final concentrations of 5, 10 and 100 mg l-1) and P (in final concentrations of 0.15, 1.5 and 15 mg l-1) addition was expressed as the degree of nutrient limitation (∆ r in mg l-1 per day). The algal response to nitrogen enrichment showed a linear increase (r = 0.997, P<0.05) of the degree of N limitation from March (∆ r = 0.171) to July (∆ r = 0.866).

enrichment bioassay; N and P limitation; Chlorella kessleri; Lake Sakadaš.

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