Materials and Methods

The study sites are the temporary lake complex located in the Eastern Hauts Plateaux (1,000 m in altitude), Ank Djemel (35°46'N-6°52'E), El-Tarf (35°42'N-7°08'E), and Guellif (35°47'N-7°E). Their salinity is around 10 g L-1. Individuals of P. spinosa were sampled in May 2005, using a plankton net of 125-mm mesh size. They were fixed in 4% formaldehyde.

For each population, 20 males and 20 females were measured using a micrometer fixed on a microscope. One numeric (setae number) and 12 metric parameters were considered according to the method of Amat (1980 modified).

The data for the three populations were compared by one-way ANOVA test. A least significant differences test (LSD) was applied in cases where differences existed among populations.

The length at first sexual maturity was determined when 50% of females presented signs of reproduction. Ovisacs were dissected, and the cysts were counted to determine fecundity. Their mean diameter was measured.

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