Sidi M’Hamed Benali lake (Algeria) is a reservoir used for recreational and fishing purposes that also harbors a rich fauna an flora. These are affected by use of pesticides in view of the increasing anthropogenic activities. In this study, levels of contaminants, polychlorinated biphenyls (PCBs), polybromo-diphényléthers (PBDEs), dichlorodiphenyltrichloroethanes (DDTs), and Lin-dane were measured using gas chromatography with electron capture detec-tion and gas chromatography mass spectrometry in four fish species (Cyprinus carpio, Barbus barbus, Hypophthalmichthys molitrix, Rutilus rutilus) of Sidi M'Hamed Benali lake. The results showed that PCBs, PBDEs and the insecticide Lindane contaminated the studied species but at concentrations, much lower that the guiding values. On the contrary, high levels of pp’DDE (p,p’dichlorodiphényldichloroéthylène) was recorded in all samples with values higher than the Maximum residue limit of 300 ng/g lipid weight (LW.) set by FAO with values as high as 3.87 x 103 ng/g LW (total DDTs) which indi-cated potential hazard not only to human consumers of the lake fishs but also a potential hazard expected to animals that prey on these fishes. 14 ng/g fresh weight (FW.) Canadian limit is also significantly lower than the values of fish from the studied lake (42-46 ng/g FW.). In light of these results, we conclude that this lake is exposed to organic pollution of anthropogenic origin and we encourage caution regarding the consumption of fish in this reservoir. It is time to make serious efforts to mitigate the lake pollution in order to protect aquatic wildlife for sustainable development.

This study was carried out to investigate the degree, the nature and the origin of pollution in Sidi M'hamed Benali Lake using the physicochemical parameters, saprobic index and cladocerans. For this purpose, water and zooplankton sampling was collected from six sites in lake during five seasons. The average seasonal values of physicochemical parameters showed that the lake undergoes a slight anthropogenic and natural pollution in the dry and wet periods. Presence of certain toxic substances (CN -, Cr, Ni) require us to be more careful in irrigation, bathe and the consumption of fishes of that reservoir. Overall, oligo-mesosaprobic to beta-mesosaprobic rotifers have been prevailing in all five seasons indicating that the water was slightly or moderate polluted. The presence of Bosmina longirostris, Daphnia longispina, Daphnia cuculata, Daphnia ambiga and Sididae diaphonosoma brachyrum indicate bacterial contamination with the intense development of the phytoplankton in the lake, especially in springs and summer. Pearson correlation analysis revealed significant correlation between all of the physicochemical parameters. However, it revealed no significant correlation between zooplanktons occurrence and the majority environmental variables values. In present investigation, the Lake water is relatively little exposed to pollution and does not undergo strong organic pollution.