Status of ichthyofauna and analysis of reservoir water quality on a small river under human stress

Abstract

Large amounts of anthropogenic loading and change of the catchment region have led to the bad quality of the surface waters of the estuary. The ecological and hygienic state of the Basov Kut reservoir's surface waters are reported, as are the findings of accounting for dead fish caused by frosts at the mouth of the Ustye River from 2011-2017, which were monitored during the same time period. It has been determined that the Bas Basin should not be used for leisure activities. Lactose-positive Escherichia coli, the Staphylococcus aureus index, the Enterococcus microbe index, and Lamblia intestinalis cysts and eggs are yearly identified in this reservoir, making amateur fisheries a threat to the population as well. Vibrio cholerae non O1 (VcnO1) was discovered in 2017. Inconsistencies in hydrochemical markers were most noticeable in 2018: odor, 2 points; color, 3; BOD5, 6.5-7.5 mgO2/dm3; COD, 40-50 mgO2/dm3. The cholera-like vibrio (non O1) was found in samples examined for hygienic, microbiological, and parasitological criteria. Decline in water quality caused by a rise in eutrophication of the reservoir due to the presence of biogenic materials, especially nitrogen and phosphorus compounds. In 2018, the "flowering" of water started in the third decade of June and continued until the fourth decade of October. Because blue-green algae toxins may accumulate in fish tissues and induce toxicity if swallowed, this process is bad for humans as well as aquatic organisms. In addition, a significant fraction of the fish sampled lacked the necessary organoleptic qualities as defined by DSTU 2284: 2010. The largest harm to the populations of fish that inhabit the Estuary during the deaths was suffered in 2012. Scientists and regulatory organizations predicted a loss of 377,4 thousand people due to the collapse of the fishing industry. There have been considerable declines in populations of industrially useful fauna due to annual deaths. In 2017, there was a major depletion of fisheries resources, estimated at over 10,32,000.  This raises serious concerns for the viability of recreational fishing in these areas and the continuation of ichthyofaunal reproduction at the Ustya River's mouth.