REPUBLIQUE ALGERIENNE DEMOCRATIQUE ET POPULAIRE MINISTERE DE L’ENSEIGNEMENT SUPERIEUR ET DE LA RECHERCHE SCIENTIFIQUE

This work aims to characterize the physical-chemic water and cyanobacterial community of Ain El Dalia dams located in Souk Ahras. For this we carried out the analyses of some physicochemical parameters (temperature, pH, dissolved oxygen, conductivity, nitrates, nitrites, ammonia nitrogen, orthophosphate, suspended matter and chlorophyll a) and identification of cyanobacteria collected. The results of physico-chemical analyses show the existence of seasonal fluctuations, the values are recorded in accordance with accepted standards. The morphological and anatomical characteristic observations of cyanobacteria collected allowed us to identify 12 genera (Microcystis, Gomphosphaeria, Synechocystis, Merismopedia, Lyngbya, Oscillataria, Phormidium, Anabaena, Pseudoanabaena, Aphanizomenon, Nodularia, and Spirulina), most of which are potentially toxic. Among these toxic genera Oscillatoria is omnipresent, Lyngbya and Phormidium are constant, Microcystis, Synechocystis and Pseudoanabaena are regular. The monthly evolution of the Cyanobacteria density show that the highest values are recorded during December, October (autumn), February, March (winter), and June (spring) However, the low values are observed during November and April months. The spatiotemporal variation of cyanobacteria densities revealed the presence of Oscillatoria, Lyngbya, Phormidium and Pseudanabaena in treated water (30 ind/l) in December and June in the site 2, cyanobacteria are strongly represented in November (40 ind /l) in February (55 ind/l) and in June (70 ind / l). In the site 3 levels over 35 Ind / l are noted in January, March, April and May. It is however the site 4 that are rated 4 pics 85 ind /l, 60 ind / l, 50 ind / l and 40ind/l respectively in October, December, March and June. The calculation of genus densities reveals the dominance of Oscillatoria and Lyngbya followed by Pseudoanabaena. Some genus prefer the autumn and spring season (Oscillatoria, Pseudanabaena and Synechocystis), other (Microcystis and Phormidium) the spring or (Lyngbya) the winter season. Ain El Dalia dams should be more closely monitored in order to better protect of users health.