The growth and some metablic activites of Anabaena circinalis, which were grown under different salinity
stress levels were followed and it has been found that these species can tolerate NaCl salinity to the
level of 80 mM and survived to the level of 0.5 M of NaCl. Higher doses of salinity caused reduction in
growth criteria (Absorbance, chlorophyll content) with the time elapsed, reduction of protein content, and
caused increasing in carbohydrate content, significance increasing in proline content was also recorded.
Addition of Ca+2 to the salinized culture caused improvement in growth and improved K+/Na+ ratio which
increase the osmoprotectant, as well as protect this organism from the toxic effect of NaCl.