Contribution à la connaissance des cours d'eau du Liban : la zonation biologique du Nahr Qab Ilias

Abstract

Les parties temporaire et permanente d'un cours d'eau du Liban central sont étudiées. Les données climatiques, hydrogéologiques, hydrographiques et biotiques du Nahr Qab Ilias mettent en relief la présence de trois zones étagées en fonction de l'altitude. Les Plécoptères dominent à l'amont et les Ephéméroptères à l'aval. Studies on Lebanese streams : the biological zonation of the Nahr Qab Illas. Intermittent and permanent parts of a chalky stream are studied. Climatical, hydrogeological, hydrographie and biological data are given. The stream is divided in three sectors. The Plecoptera are the main group of the zoocenosis in the upper part. The Ephemeroptera dominate in the lower part.

River Dan, headwater of the Jordan, an aquatic oasis of the Middle East

“…The conditions of stable flow may be considered as adverse to many species of Plecoptera: Presenting his data on the Lebanese Nahr Qab Ilias, Alouf (1983) comments on the fact that 5 of the 6 species of Plecoptera found there are restricted to the seasonally dry upper segment of the stream. Protonemura zernyi, the only species present in the permanently flowing part of the streams is also one of the three species of stoneflies that live in the Dan.…”

“…However Malicky reports a crenal-rhithral-potamal type of zonation (Illies, 1961) in the rivers flowing down from the high mountains of Cyprus. Alouf (1983) divides the 5 km long flow of Nahr Qab Ilias, a tributary of the Litani in Lebanon, into two zones: the upper, seasonally flowing part and the lower, permanent one. He considers them as sub-zones of the rhithral.…”