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Response of Fish communities to environmental parameters in the rivers of the Kharasan Sub Basin in Chaharmahal and Bakhtiari Province
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Hasan Fazli *   , Behzad Rahnama , Hassan Nasrollazadeh Saravi , Eisa Hajiradkouchak , Gholamreza Daryanabard |
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Abstract: (4 Views) |
Understanding the influence of abiotic factors on fish community dynamics is crucial for effective aquatic ecosystem management. This study aimed to investigate the effects of physicochemical parameters on fish assemblages across the rivers of the Khersan sub-basin (Marbareh, Beshar, and Khersan rivers) in Chaharmahal and Bakhtiari Province, Iran. Multivariate and univariate data analyses were performed using PRIMER software. Community structure was evaluated using non-metric multidimensional scaling (nMDS) and distance-based linear modeling (DistLM). High correlations were observed between, such as phosphate and water temperature, silt–clay and sand, BOD5 and pH, BOD5 and NH3, and COD and dissolved oxygen. The ichthyofauna consisted of 15 species, with Cyprinidae being the most diverse. nMDS results indicated that fish assemblage structure was primarily driven by spatial heterogeneity and station-specific characteristics rather than seasonal variations, though some distinct clustering was observed in winter and spring. Species-specific distribution patterns were evident, with Garra rufa and Capoeta trutta showing restricted distributions, while Chondrostoma regium exhibited a broader ecological tolerance. PERMANOVA results indicated no statistically significant effect of season or station, suggesting relative temporal stability. DistLM identified dissolved oxygen, EC, TOM, substrate, temperature, nitrate, ammonium, ammonia, and water discharge as the primary environmental drivers. Overall, fish community structure in the Khersan sub-basin exhibited adequate diversity, with cyprinids being dominant. Community structure was also influenced by physicochemical parameters, substrate type, and water discharge, and was simultaneously affected by hydrological conditions, spatial factors, and trophic status. Seasonal changes exerted their influence indirectly, through habitat alteration. Additionally, the limited presence of the non-native rainbow trout highlights the need for habitat conservation in the region. These findings can serve as a baseline for future ecological assessments and conservation planning within this sub-basin.
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| Keywords: Fish, Community structure, Environmental variables, Multivariate analysis, Iran |
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Type of Study: Research |
Subject:
Special
Received: 2026/05/31 | Accepted: 2026/07/26 | Published: 2026/07/26
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