Biodiversity and distribution of selected freshwater mollusks and crayfish along a mineralization gradient in the Zarafshan River, Uzbekistan

KHUSNIDDIN BOYMURODOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
JONIBEK SAIDKULOV (Department of Foundational and Social Sciences, Jizzakh Sambhram University. Hamroqul Nosirov Street, 3. Jizzakh 130100, Uzbekistan)
SAYFULLA KHORAZOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
TOZAGUL JABBOROVA (Department of General Methodological Sciences, University of Economics and Pedagogy. Islom Karimov-13, Karshi 180119, Uzbekistan)
BOBUR SABOXIDDINOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
OMON MIRZAMURODOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
BAXTIYOR ALIYEV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
SULTON SUYAROV (Department of Ecology and Life Safety, Faculty of Geography and Ecology, Samarkand State University. University Boulevard 15, Samarkand 140100, Uzbekistan)
BEKZOD OTAKULOV (Department of Ecology and Life Safety, Faculty of Geography and Ecology, Samarkand State University. University Boulevard 15, Samarkand 140100, Uzbekistan)
AZAMAT EGAMKULOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
NADIR KHASANOV (Department of Biology, Navoi State University. Ibn Sina 45, Navoi 210100, Uzbekistan)
FARRUKH DJALILOV (Department of Biology, Samarkand State Pedagogical Institute. Spitamen Shokh Street 166, Samarkand 140100, Uzbekistan)
SUKHROB BOYMURODOV (Department of Zoology, National University of Uzbekistan named after Mirzo Ulugbek. 4 University Street, Tashkent 100174, Uzbekistan)
MATNAZAR RAXIMOV (Department of Zoology, National University of Uzbekistan named after Mirzo Ulugbek. 4 University Street, Tashkent 100174, Uzbekistan)
ZUVAIDULLO IZZATULLAEV (Department of Ecology and Life Safety, Faculty of Geography and Ecology, Samarkand State University. University Boulevard 15, Samarkand 140100, Uzbekistan)
KHUDAINAZAR YUNUSOV (Department of Biology, Ecology and Medicinal Plants, Samarkand State University of Veterinary Medicine, Livestock and Biotechnologies. Mirzo Ulugbek 77, Samarkand 140100, Uzbekistan)
ZAFARJON MUSTAFOYEV (Department of Human Anatomy, Samarkand State Medical University. Samarkand 140100, Uzbekistan)

Biodiversitas Journal of Biological Diversity
Vol. 27 No. 4 (2026)

Abstract. Boymurodov K, Yunusov K, Izzatullaev Z, Raximov M, Boymurodov S, Djalilov F, Khasanov N, Egamkulov A, Otakulov B, Suyarov S, Aliyev B, Mirzamurodov O, Saboxiddinov B, Jabborova T, Khorazov S, Saidkulov J, Mustafoyev Z. 2026. Biodiversity and distribution of selected freshwater mollusks and crayfish along a mineralization gradient in the Zarafshan River, Uzbekistan. Biodiversitas 27 (4): d270425. https://doi.org/10.13057/biodiv/d270425. The Zarafshan River basin is characterized by a distinct hydro-chemical gradient shaped by intense urbanization and industrial activity, which significantly impacts its biological integrity. This study evaluates the taxonomic diversity and distribution of four key freshwater macroinvertebrate families (Unionidae, Corbiculidae, Lymnaeidae, and Astacidae) along a documented mineralization gradient in the Zarafshan River basin. Field surveys were conducted from 2023 to 2025 at 12 sampling stations representing varying anthropogenic pressures. Taxonomic composition was analyzed alongside hydro-chemical parameters, including Total Dissolved Solids (TDS) and nutrient levels. A total of 11 species, belonging to 3 classes, 4 orders, 4 families, and 7 genera, were identified. Data analysis revealed a marked decline in both species’ richness and individual density as water mineralization increased from 300 mg/L (Site Z1) to 1600 mg/L (Site Z4). Ecological classification identified the predominance of phytophilic (5 species, 45.4%) and peloreophilic (3 species, 27.3%) groups. Faunistic similarity analysis, using Jaccard and Ochiai indices, showed the highest similarity between stations K1 and A2 (Ochiai 0.95), while the lowest similarity was recorded between the most impacted stations Z4 and K4 (Jaccard 0.45). The observed spatial shifts in community structure suggest that elevated mineralization and organic loading are primary drivers of macroinvertebrate distribution in the basin. These findings characterize the environmental tolerances of the target taxa, providing foundational data for developing future bioindication frameworks in the Zarafshan River ecosystem.