Salinity effects on survival, growth and morphometry of four Egyptian Artemia populations (International Study on Artemia.: LXVII)

Four Artemia populations from northern Egypt, a bisexual one from Wadi El-Natrun Lake, two coastal parthenogenetic ones from Borg El-Arab and El-Max saltworks and an inland parthenogenetic form from Qarun Lake, were assayed for their survival, growth and morphometric responses measured in laboratory experiments at salinities of 35, 80, 120, 150 and 200 g l(-1). The survival rate was determined using regression analysis and analysis of covariance. The bisexual population ( Wadi El-Natrun: WN) exhibited its best survival at 80 g l(-1). All parthenogenetic strains studied performed similarly ( in terms of survival) at all salinities investigated. The population growth rates were based on Von Bertalannfy's equation. In all salinities, WN population had the lowest growth rate ( based on K values) among all Artemia populations tested. It is obvious that parthenogenetic populations tolerate a broader range of salinities compared to the bisexual one. The two coastal asexual strains had similar survival, growth and morphometric characters at all salinities. Discriminant function analysis based on specific morphometric parameters permitted the assignment of adult Artemia individuals to their population of origin with a score as high as 84.6%. Furthermore, specific morphometric parameters ( such as the furcal length and the number of setae in each furcal branch) are suitable discriminating characters among the populations studied.