Limnological study of mesotrophic lake taham in zanjan province

The Taham dam reservoir is a mountainous lake with 317 ha near to Zanjan. This study have been focused on biotic and abiotic factors of this lake. The results showed the less abundance of phytoplankton with 2×106 l-1 where abundant of zooplankton was 266 l-1. Bacillariophyta and Chlorophyta belong to phytoplankton and Rotatoria belong to zooplankton were dominated among identified plankton phyla. There were identified 45 and 32 genera of phytoplankton and zooplankton respectively. There were identified 5 groups of benthos that Tubificidae, Hirudina had the most frequency. The ichtiology survey showed presence of 6 species in the lake that Alburnoides bipunctatus, Capoeta capoeta,, Leuciscus cephalus were the most abundance in the materials. L. cephalus was observed with the maximum size of 870 gr. The hydro chemical results indicated low phosphorus values while total nitrogen was varied from 0.3 to 0.6 mg l-1. Chl-a was varied from 7.9 to 25.9 µg l-1. The oxygen amount was 4.5 to 8.4 even in 65 meter depths. The Carlson trophic model showed that the Taham lake is at early stage of mesotrophy while other lakes and wetland in north of Iran were progressed in mesotrophic level. In this paper the biotic and abiotic parameters have been compared with some water bodies in north of Iran.