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En 2008, 33 espèces de Cladocères, Copépodes et Rotifères ont été observées dans le lac Sidi M'hamed Benali (contre 12 seulement en 1992).Les Copépodes dominent en mars, avril, juillet, août et septembre, avec respectivement des dominances (Do) égales à : 56,6 %, 55,0 %, 55,0 %, 46,4 % et 90,0 %. Les Cladocères dominent en février (Do = 37,2 %), mai (Do = 47,4 %) et décembre (Do = 48,6 %). Les Rotifères sont extrêmement abondants et présentent une large dominance en janvier (Do = 95,3 %). La population zooplanctonique est très faible en juillet et en août. Au cours de l'année le peuplement varie en fonction de la température, des conditions hydrologiques, de l'abondance de la nourriture et de la prédation par les poissons.
In 2008, 33 species of Cladocers, Copepods and Rotifers have been observed in Sidi M’hamed Benali Lake (against only 12 species in 1992). The Copepods dominate in March, April, July, August and September, respectively with dominance (Do) equal to 56.6 %, 55.0 %, 55.0 %, 46.4 % and 90.0 %. Cladocers dominated in February (Do = 37.2 %), May (Do = 47.4 %) and December (Do = 48.6 %). The rotifers are extremely abundant and have a wide dominance in January (Do = 95.3%). The zooplankton population is very low in July and August. During the year, the population varies with temperature, water conditions, abundance of food and predation by fishes

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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.

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The objective of this work is firstly an ecobiological study, which aims to determine whether salinity is favorable for a good reproduction rate of cysts in the Artemia salina L., a species known for its use in aquaculture. Secondly, a short-term test of ammonium sulfate toxicity on its vitality is carried out as its environment is permanently subjected to sulphate-laden waste. The work consists of subjecting the species to different salinities in order to produce a good yield in cysts, which once recovered, hatching and breeding is maintained until individuals reach the adult stage. A toxicological study using toxicity test (CL50) is then conducted to study the resistance of these adults with various concentrations of ammonium sulphate. The results obtained from the ecobiological study show a mean similar to the natural environment (p > 0.05) with a favorable concentration for the reproduction of the species at a salinity of about 75 g dm -3 . The toxicity test indicates a CL50 equal to 75 mg dm -3 after 24 hours. It is obvious that Artemia salina L. can be cultivated by controlling its reproduction by varying the salinity rate for its use during different seasons of the year, thus ammonium sulphate from waste is considered as a limiting factor.