Effect of Rainbow Trout culture sewage on macro benthose communities of Marbor River, Isfahan province, during low water seasons

The aim of this study was to determinate the effect of trout farm sewage on fecundity and diversity of macro invertebrate benthoses with some biological indices. This study was done on the Marber River in Semirom city، the southwest area of Isfahan province. Sampling was took place in five stations on summer of 2012، monthly using a Surber sampler (30. 5cm×30. 5 cm). Sampling in each station was done in three points (edges and middle of the river). Captured samples were fixed in 4% formalin and were taken to the laboratory. In laboratory animals were collected with a sieve of 500 microns in diameter springs to assort and identify to the least level possible (families and genera). In this study، several biological parameters such as: Abundance، Biomass، Similarity، Shannon-Wiener، EPT/ Chironomidae، Margalef richness، Hylsnhvf، BMWP index and ASPT index was used. Eventually 20 families، with 10 orders، 7 classes and 5 phyla were identified.