Relationship between nitrate and phosphate assimilation in some freshwater and saltwater algae

Abstract

The objective of this research is to study how the deficiency of nitrate affects the dynamics of phosphate acquisition and vice versa, in cultures of H. pluvialis, Ch. dissectum and D. salina at two levels of light intensity (2 and 8 klx) and two levels of salinity (1 and 4 M NaCl) for saltwater D. salina. In both freshwater species H. pluvialis and Ch. dissectum, deficiency of one of the nutrients reduced the assimilation rate of the other nutrient. As for the saltwater D. salina, a similar effect of suppressing the assimilation of one nutrient by lack of the other was observed only at the low salinity of 1M NaCl. An increase of salinity to 4M NaCl per se led to inhibition of the absorption of both nutrients, but a lesser degree. Noteworthy, at a salinity of 4M NaCl, a deficiency of one of the nutrients no longer affected the assimilation of the other. No statistically significant effect of increasing light intensity from 2 to 8 klx on the dynamics of nutrient absorption was observed in any of the studied species.