Influence of hydrochemical indicators on the age and density of bivalve molluscs, spread in the lower reaches of the Zarafshan river

. Hydrochemical parameters of water in ecosystems of Gijdivan district of Bukhara region: O2 content 4,9 ± 0,5 mg / l, Cl2 312 ± 14 mg / l, mineralization - 992-1402 mg / l and oil products about 0,6-0,8 mg / l, it turned out that the amount of these elements in the water exceeds the permissible norm. The following conclusions were made on the basis of the study of the status of the species listed in the “Red Book” in aquatic ecosystems of the lower reaches of the Zarafshan river. We found that the population of the species Colletopterum and Corbicula in the village of Sultanabad in the Navoi region is a growing population, while the population of the species Colletopterum and Corbicula in the Gijduvan region of the Bukhara region is decreasing.


Types of molluscs
The territory of Sultanabad village, Navoi region (age and density m2) О2 (oxygen) (m/g)

Oil products
(mg/l) In the aquatic ecosystems of the territory of Sultanabad village, Navoi region, the hydrochemical parameters of water, amount of O2, Cl2, mineralization and the amount of oil products in the water are approximately at the average permissible level, it was noted that in these aquatic ecosystems the distribution, density, nutrition, growth and variability of shells of bivalve mollusks are not adversely affected. It was observed that in the population the density of 2-3 years-olds is 6-7, the density is lower in 8-9-year-olds. The high density of youth indicates that this population has the potential for recovery in the future. This is due to the fact that young mollusks reproduce and recover rapidly in the population.

8-9 years
The influence of human economic activity on the lower reaches of the Zarafshan river dates back to ancient times. This effect is observed in the hydrological regime of the river, which changes the quantity and quality of water resources. At present, part of the river in the Bukhara region is fed mainly by return water from cultural fields, industrial wastewater and groundwater. Rapid development of agriculture and industry in the Samarkand, Bukhara and Navoi regions since the 1960 s has led to a complete depletion of surface and groundwater resources in the region, their pollution with industrial waste and sewage.
As the level of salinity of river water increases, the amount of toxic ions (magnesium, sodium, potassium, sulfates and chlorides) in them also changes depending on the length and time of the river, as well as the water content of the year. As a result, the water quality of many rivers, including the Zarafshan, changes not only in the lower reaches, but also in the middle reaches.
Hydrochemical parameters of water in ecosystems of Gijdivan district of Bukhara region: O2 content 4,9 ± 0,5 mg / l, Cl2 312 ± 14 mg / l, mineralization -992-1402 mg / l and oil products about 0,6-0,8 mg / l, it turned out that the amount of these elements in the water exceeds the permissible norm.
The following conclusions were made on the basis of the study of the status of the species listed in the "Red Book" in aquatic ecosystems of the lower reaches of the Zarafshan river. We found that the population of the species Colletopterum and Corbicula in the village of Sultanabad in the Navoi region is a growing population, while the population of the species Colletopterum and Corbicula in the Gijduvan region of the Bukhara region is decreasing.