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Evaluation of the biodiversity structure in the Sirvan River tributaries based on ecological indicators
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Behzad Rahnama *   , Eisa Hajiradkouchak , Hasan Fazli , Narges Alishah , Matin Shakoori , Rahimeh Rahmati |
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Abstract: (6 Views) |
The current study aimed to explore the diversity, abundance, and community structure of fish species over a one-year period, examining seasonal variations across six distinct stations along the Sirvan River. This research assesses spatial and seasonal fluctuations in biological indices such as Shannon, Simpson, Margalef, and evenness. Employing statistical and multivariate analyses, including ANOVA and clustering, enhances the understanding of ecological differences across various seasons and locations. The seasonal analysis of fish species abundance throughout the year indicated that their diversity and population density are significantly affected by seasonal variations.The findings revealed that the composition and structure of the fish community in the Sirvan River are considerably influenced by both temporal (seasonal) and spatial (station-based) factors. Increased biodiversity noted during warmer seasons (spring and summer) and in downstream stations with improved physicochemical conditions-such as stations 5 and 6-suggests a positive relationship between favorable environmental factors (e.g., elevated temperature, adequate dissolved oxygen levels, gentle flow, and suitable substrate coverage) and enhanced species diversity.Among the fish species identified, three-Carrasius auratus, Rhinogobius similis, and Carrasius gibelio-are recognized as exotic to the region. Overall, the observed trends in the Sirvan River illustrate the interaction of environmental factors, human activities, and the ecological characteristics of fish species. The results highlight that biodiversity is not merely a function of species count, but also depends on even distribution, functional composition, substrate conditions, and environmental threats. Consequently, ecosystem-based strategies should be implemented in water resource management to conserve and restore riverine biodiversity.
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| Keywords: Biological indices, ecological approach, fish ecosystem, Sirvan River. |
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Type of Study: Research |
Subject:
Special
Received: 2025/08/3 | Accepted: 2025/11/9 | Published: 2025/12/8
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