identification of benthic population structure in the abgarmeh saleh abad river, the ilam province

aquatic invertebrates are the major group of freshwater animals in aquatic ecosystems in terms of biology and food chain. this study was conducted to identify benthic communities in four stations of the abgarmeh river (saleh abad, the ilam province) during 2007-2008. in this study eighteen families of benthose such as naididae, tubificidae, lumbricidae, erpobdellidae, gammaridae, haliplidae, corixidae, gerridae, perlidae, ecdyonuridae and 12 genera of four class leeches, crustaceans, aquatic insects and oligochaeta were identified including diptera with 19.64% and leeches (hirudinea) with 4.04% having the highest and lowest frequencies during the study period, respectively. the highest frequency was recorded in december with 86 samples/cm2 and the lowest frequency with 42 samples/cm2 in april. diptera had the highest frequency in the first, second and third stations while odanata in the fourth station. 620 specimens were identified, belonged to seven orders, of them diptera with 26.61 had the highest frequency among the aquatic insects. in general, the diptera had the highest frequency and plecoptera and trichoptera the lowest abundance throughout the year in the abgarmeh river.