Urmia Lake has been suffering from drought since last 10 years, during this period the surface area and water volume of the lake has reduced largely and water salinity has increased to saturation level reaching to 350 ppt. Artemia population has diminished to less than one Artemia in one cubic meter compared to one animal/l during the high water levels before 1998. High salinity inhibits cyst hatching, limits availability of nutrients especially unicellular algae and causes high mortality due to excessive stressful condition. A number of researchers have proved the adverse effect of salinity on growth, survival and reproduction of Artemia populations including A. urmiana and A. parthenogenetica (Vanhaecke, et al., 1984; Dana and Lenz, 1986; Wear, et al., 1986; Wear, R. G. and S.J. Haslett, 1986; Browne and Wanigasekera, 2000; Abatzopoulos et al., 2003; Baxevanis, et al., 2004; El-Bermawi, et al., 2004; Agh et al., 2008). Maintenance of Artemia at high salinities have been always very difficult at laboratory conditions (Wear and Haslett, 1986, Wear et al., 1986). On the other hand live Artemia in low densities have been observed at very high salinities in natural biotopes. The aim of this research was to evaluate the tolerance level of A. urmiana and A. parthenogenetica from Urmia Lake and lagoons at the vicinity of Urmia Lake to rapidly increasing salinity at laboratory condition.
