The present work aimed to study the distribution of Cladocera and Rotifera populations in two reservoirs in western Algeria (Sidi Mhamed Benali Lake and Sarno Dam), taking into account two physical parameters: water temperature and pH in the Mediterranean climate. The abundance of zooplankton groups, specifically Cladocerans and Rotifers, exhibited an evolution closely paralleling the environmental characteristics of the ecosystem. Both populations were monthly sampled from January to July 2017 using a plankton net of 64μm mesh size. In total, 35 taxa were recorded, of which 18 species belong to the Cladocera and 17 others are members of the Rotifera. The results of this comparative study showed, on the one hand, heterogeneity in the specific richness of Cladocera and Rotifera on a spatiotemporal scale and a relationship with the physical quality of the water in the two environments on the other hand. Furthermore, Sidi Mhamed Benali Lake appeared to be more diverse and the richest in Cladocera. Overall, the highest taxon richness and abundance were recorded during the rainy season from January to April (35 species) compared with 22 taxa in the dry season. These results were confirmed and clearly demonstrated by the results of the principal component analysis (PCA).