Impact de l'anthropisation du lac sud de Tunis (Tunisie) sur la structure automnale des peuplementsde nematodes libres

Abstract

The answer of the free nematode populations to the physico - chemical state of “ lake ” south Tunis has been studied in autumn 96 from 10 sampling sites. Their very weak specific diversity (Hermi, 2001) and the non selective détritivorous proliferation (1B) bound to the strong contents in recorded organic matter (Hermi, 2001) revealed the sensitivity of nematodes to the eutrophication and nutritionnal pollution. According to several interrelationships calculations, the waters saturation in oxygen, their contents in abeyance matter and in nitrogen as well as the sediments granulometry and their contents in certain heavy metals, appeared the most lagoonar determining parameters. Otherwise, the answer of nematofaunistic communities living in South lake was very dependent of the state of deterioration of the sampling site. Thus, the weakest and trophic diversities were observed s in the most enclose western sector, there where predominated Theristus flevensis, a species able to tolerate strong contents in organic matter. On the other hand, the station relatively less eutrophic of the Radès Channel were revealed the more varied as well according to trophic index that according to the number of nematode species inventoried.