Production indicators and elements of the energy balance of the relict mysida Mysis relicta (Loven) population on Lake Yuzhny Volos

Field studies and a retrospective analysis of distribution and life cycle features of the glacial relict Mysis relicta (Loven) on Lake Yuzhny Volos on the southern border of distribution of the species on the European continent were carried out. The size-age structure, number and density of the mysida population did not change over a half-century period on Lake Yuzhny Volos. Life cycle features, which consist in the existence of parallel lines of alternating one-year and two-year generations, remain stable. The mysida production characteristics were determined. It is shown that the somatic production of two-year generation females at the level of the individual and the population is two times higher than that of one-year generation females. During the gestation of juveniles, the female consumes the body weight energy equivalent, which is equal to 2.13 cal·individual–1 for a one-year generation and 7.32 cal·individual–1 for a twoyear generation, 9.5·108 and 25.5·108 cal for all individuals of one-year and two-year generations. Egg production for life in the mysida population was 29.5·108 cal, which is comparable to the total somatic production. The exuvial production of mysids at the level of the individual and the population turned out to be ten times higher than the somatic one. The energy spent for respiration is 900 times higher than the somatic production values for one-year generation females and 1200 times for twoyear generation females. The coefficient K2 values appeared to be close for the both generations (0.032–0.034) and are represented by very low values compared to the freshwater macrozoobenthos of temperate latitudes.