Effluence of Aquaculture on Bioabundance of Macroinvertebrates in Dohezar River in Tonekabon

The present study aims to explore، the Dohezar river biological diversity and abundance of Macro benthos using demographic indicators from October 2010- 0ctober 2011. Samples of macroinvertebrates were collected monthly from 7 stations designated as station 1 (upstream of the river course) to station 7 (downstream of the river course) for a period of 12 months. A combined total of 60 families and 18 orders and 7 class species of macroinvertebraits were encountered in the study. with the sampling of benthic fauna of some physic-chemical factors such as temperature، BOD5، DO، pH were also measured at the station in that the above factors does showed significant difference at the probable level of 5% (P<0. 05) Except DO that does not showed significant difference at the above-mentioned stations. The fauna data surveyed with using SHANON and EPT & EPT/Ch biological index. One-sided variance analysis test of index indicates existing a significant difference among the stations in probable level of 5 % (P<0. 05). According to EPT index، the highest mean belongs to station 3with 70. 66 score mean possibly due to minor contamination and the lowest score belongs to station 7 with 22 mean score which has the average level of organic contamination. The EPT/Ch index، the highest mean belongs to station 1with 1. 11 score mean possibly due to minor contamination and the lowest score belongs to station 7 with 0. 31 mean score which has the average level of organic contamination.. The SHANON index، the highest mean belongs to station 2with 2. 27 score mean possibly due to minor contamination and the lowest score belongs to station 7 with 1. 77 mean score which has the average level of organic contamination.