FLUCTUATION OF TOTAL NUMBER OF FISH LARVAE AND THEIR MASS TYPES DEPENDING ON ENVIRONMENTAL FACTORS IN THE MESHA BAY OF THE KUIBYSHEV RESERVOIR IN 2012-2018
The article analyzes fluctuations of the number of fish larvae in the littoral of the Mesha Bay of the Kuibyshev Reservoir in the spring period of 2012-2018 in relation to the level and temperature regimes. The assessment of their species diversity has been given. In these years there were found 7-13 larvae species in catches. The minimal number of larvae species in the catches were registered in 2013, the maximum number - in 2018. The total number of fish larvae varied in these years 57.4-807.0 sp/effort. In terms of 1m3 it made 807.0-5659.1specimens. For all the years of research roach larvae were the dominant species in the catches, ranging from 42.7% to 80.7% of the total catch. The average number of roach larvae was 105.8 sp/effort. The second place in the catches belonged to bream larvae whose average number made 43.4sp/effort (their average part in catches is 29.3%). The third place in the catches in different years belonged to ide larvae, silver bream, bleak and silver crucian. Among them silver bream larvae had the greatest number - 7.5 sp/effort. Larvae of Ide, bleak and silver crucian on average ranged 3.2-3.8 sp/effort. The largest magnitude of the number fluctuation was found in silver bream and bleak. Their variation coefficient ranged within 115.9-117.1%. Bream had a relatively steady replenishment of the larvae (Cv = 37.9%). There is a positive correlation between the abundance (sp.) of roach and bream larvae, but between the abundance indicators (%) the correlation is negative, i.e. the higher the percentage of roach dominance, the smaller the proportion of bream in the catches. Within 2012-2018 Shannon index of species diversity in fish larvae ranged from 0.96 to 2.09 bits. There is a negative correlation between Shannon index and indices of abundance of roach and bream larvae