Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : ECOLOGICAL AND BIOLOGICAL STUDIES ON ALGAL COMMUNITIES OF SOME REGIONS OF WADI EL-RAYAN,EGYPT

Auteur : HASSAN, SHERIF HASSAN MOHAMED.

Etablissement de soutenance : Beni-Suef University

Grade : Doctor of Philosophy (PhD) in Microbiology 2005

Résumé partiel
Egypt is one of the developing countries which is exposed and affected by different environmental pollutants. The ecological effects of these pollutants on the natural ecosystems especially the algal communities need to be monitored continuously. Wadi El-Rayan is one of the most popular protected areas in Egypt, and considered as par excellence the most arid among the desert regions of the world. Human impacts were the main threat to this natural area and the efficient control over these activities in is one of the main topics for the [Egyptian government. This takes place through some strategies and [approaches to protect and expand the available natural resources base : jaiming to increase productivity, reduce migration and improve the living condition in this area. One of the main points to achieve the previous approach is surveying the living organisms that could tolerate the anthropogenic activities. • In this investigation, three locations along the second lake shore of I Wadi El-Rayan were chosen, each location including three different I habitats designated as water and wet and dry soil, and classified to 36 stands. • These stands were monitored seasonally to record the variation in [ their physicochemical characters and each stand was studied qualitatively and quantitatively for its algal community’s content during the different seasons.  » The physicochemical characters of the soil samples revealed that, pH was slightly alkaline and ranged between 7.6-8.1 and 7.3-8.3 of wet t and dry soil types, respectively. While it recorded 8.22-8.77 in the water samples during the different seasons. The maximum moisture content of the wet soil samples was recorded during autumn and winter seasons (25.3 and 22.3%, respectively), while it was very low and more or less similar among the other seasons. Both wet and dry soil types were poor in the organic carbon content during all seasons. Seven heavy metals (Cu, Co, Mn, Ni, Zn, Fe and Pb) were monitored seasonally in the soil samples. The wet soil samples recorded high cobalt content during summer, in contrast it was not detectable during the winter season. Copper recorded its maximum value during autumn. The dry soil type recorded its highest content of cobalt during winter and autumn, whereas lead recorded maximum limits in spring and summer. 1 Eight algal species were identified in the wet and dry soil habitats ; I those were belonging to Cyanophyta (six species) and Chlorophyta :(two species). Cyanophyta was detected in high percentage than Chlorophyta to reach 96% during all seasons in the wet soil habitat. A total of 69 species belonging to four algal phyla (35 Bacillariophyta, 19 Cyanophyta, 13 Chlorophyta and only two belonging to Euglenophyta) were identified in the water habitat Bacillariophyta were dominant during winter and spring, Cyanophyta dominated during summer season and Chloropyhta reached its highest species number during spring and summer seaso

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