عنوان مقاله [English]
The Lavandavil river of Astara is from independant rivers of Astara-Talesh sub-basin that runs in south west and west of Astara city and joins the Caspisn sea in Lavandavil city. Identification of macrobenthic funa of Lavandavil river, determination of benthic biomass in every square meter in each station,determination of biotic index in every station, determination of average temperature in every month and during a year and finally assessing the natural productivity potential of this river are the goals of this study. For this purpose, in 18 km long of this river 6 stations were determined (every 3 km one station). Sampling was carried out using a 50×50 surber sampler and stone washing monthly. This operation was being done for 1 year (July 2007 to June 2008). In this study, some genera of three phylum of invertebrate (Annelidae, Arthropoda & Mollusca) were identified. From Annelidae two classes (Oligochaeta & Hirudinea) were identified. From Arthropoda and Mollusca two classes (Crustacea and Insecta) and one class (Gasteropoda) were identified respectively. Density and diversity of different genera of macrobenthics in sampling stations was rather high but in the last station (6th) the diversity of species decreased and the density increased significantly. Also, seasonal density and biomass average in spring and summer were significantly higher than in autumn and winter. According to biotic index measurement, the annual abundance of macrobenthics was 23.78, the productivity potential of this river was 265.22 kg/ha/year and the annual average weigth of total biomass in all the stations was 3.86 gr/m2. This study showed that the biotic status of this river is 1.80 that according to quality classification of waters, this river belongs to class II.