Studies of the Kuibyshev reservoir

 

Ichthyological material was collected in the Meshinsky Bay and the adjacent waters of the Volga-Kama reach of the Kuibyshev Reservoir.

 

Quantitative samples of young fish were collected in coastal areas (depths of 0.5 - 1.7 m) using a fry drag, 2 m high, 6 m long, at standard monitoring stations in the study area in the main biotopes of the coastal part of the reservoir. Samples were fixed on site with 10% formalin.

 

The level regime in the Kuibyshev Reservoir in the summer fluctuated from 52.84 to 52.88 mBS. In the study area, the water temperature on the surface varied from 24.2 to 27.3˚C. The water temperature at depth was lower than on the surface throughout the observation period and varied from 23.4 to 26.8˚C. The temperature dynamics at depth corresponded to the dynamics of this indicator on the surface. The oxygen content varied significantly in different observation periods and at different depths. Thus, at the hydrological post, this indicator on the surface was (5.1-9.3 mg/l), and at depth (3.1-8.8 mg/l). The oxygen content in the bottom layers of water was lower than on the surface. A lower oxygen content was noted in the morning compared to daytime and evening observations. In the catches of young fish in the lower part of the bay, bleak, roach and perch prevailed, in the upper reaches of the bay, where more limnic conditions are observed, young silver carp and carp already prevailed in the catches, which confirms spring observations about the effective spawning of these species in the current year.

 

Studies were also conducted on the state of overgrowth of shallow waters, spawning grounds and fattening of commercial fish species using the example of Meshinsky Bay of the Kuibyshev Reservoir. For this purpose, the density, projective cover, and the establishment of dominant species of macrophyte thickets were determined. To assess the food supply for fish in overgrown shallow waters, samples of phyto-, zooplankton and zoobenthos were collected, fish were caught in mown areas in the vegetation using fixed nets and traps, and abiotic environmental parameters were recorded at the boundary and inside the plant communities: depth, transparency, temperature, oxygen content, type of soil.

 

At each point, environmental parameters were recorded at 2 stations: at the boundary of the vegetation and in the thickets, where the vegetation was mown (2 mown per station) using a frame with an internal area of 0.25 m2. Fouling organisms and miners were collected from the stems of one of the mown cuts at each station.

 

It was revealed that the habitat-forming species of shallow waters are Phragmites australis (Cav.) Trin. ex Steud and Typha angustifolia L. It can be stated that at the points under consideration the density of associations is higher for the southern reed, and the biomass is higher for the narrow-leaved cattail.

 

VNIRO Press Service