Study on the structure of benthic macroinvertebrates in the Azad river affected by rainbow trout (Oncorhynchus mykiss Walbaum, 1972) fish farm effluent

Document Type : scientific research article

Authors

1 Fisheries department, Faculty of Natural Resources of University of Kurdistan, Sanandaj, Iran.

2 Master's degree in Fisheries department, Faculty of Natural Resources of University of Kurdistan, Sanandaj, Iran.

Abstract

Discharge of fish farm untreated effluent can be one of the point source pollution and effective in changing the structure of the benthic macroinvertebrates of rivers. Therefore, the benthic macroinvertebrates of the Azad river were sampled to determine its population structure during 3 sampling periods in spring (low density farming), summer (high density), and autumn (medium density) 2023 at 3 stations including 1) upstream or control station, 2) farm effluent outlet, and 3) from distance of 650 meters after the fish farm. In present study, 22 taxa belonging to 9 orders and 6 phyla were identified overall. The Baetidae and Gammaridae had the highest abundance with %41.19 and %22.06 respectively and some taxa such as Chironomidae, Tubificidae, Simuliidae, and Naididae were in the next ranks. determining the abundance of benthic macroinvertebrates showed that the difference was significant only among different seasons, so that the highest abundance was obtained in summer and autumn (p<0.05), among which Baetidae in autumn, Gammaridae in summer and Chironomidae in spring had the highest percentage of abundance. Although spatial changes were not significant, but the trend from station 1 to station 3 was increasing. In general, the results of the present study showed that the footprint of the effects of fish farm effluent on the distribution and structure of benthic communities was relatively clear, since its abundance increased significantly in summer and at downstream stations with the highest aquaculture effects simultaneously.

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Journal of Utilization and Cultivation of Aquatics
Volume 15, Issue 1
April 2026
Pages 211-226

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