Abiotic Factors Effect on the Distribution and Density of Species of the Families Unionidae, Pisididae, Euglesidae and Corbiculidae in High Mountains of the Kashkadarya Riverside Zone

As a result of the study, it has been identified that the water temperature in the Kashkadarya River is 18–24 °C, the water clarity is 0.51–0.62 m and the water flow rate is 0.72–0.84 m/sec. The species of bivalve mollusks Sinanodonta gibba, S. orbicularis, S. puerorum, Colletopterum cyreum sogdianum, Corbicula cor, C. fluminalis, C. purpurea, Corbiculina tibetensis, C. ferghanensis are widespread in the region. The abiotic factors discussed in the paper play an important role in the distribution of mollusks. There are 13 species of bivalve mollusks in the mountainous region, which is the head part of the river, 9 species in the middle part of the hill region of the river and 6 species in the lower desert region.