The Effect of Salinity and Nutrient Load on the Ecosystems of Selected Lakes in the South of Siberia

Salinity largely determines the species diversity and structure of food web in lake ecosystems. Many studies have been focused on salinity tolerance various plankton species. There are fewer investigating modifications interactions under effect salinity. An appropriate system for such is closely located lakes different We took samples during summer stratification analyzed physicochemical biological characteristics 20 (salinity 0.1-35 g/l) southern Siberia order to provide general description this test a number hypotheses about web. The analysis revealed two key factors structuring ecosystems studied lakes. composition zooplankton was determined by salinity, with decrease transformation community from diverse up 3 dominance large daphnia (3-8 g/l), copepods (> 8 small cladocerans rotifers (20-30 Artemia 30 g/l). top predator (fish) eliminated at above 10 g/l. biomass did not depend but significantly increased an nutrient load. load also had significant concentration total phosphorus, turbidity transparency water, chlorophyll “a”. Thus, we recorded (bottom-up control) trophic levels parameters water transparency, while transformed chain top, leading disappearance fish change dominant zooplankton. At same time, affect levels. In detect top-down effects saline lakes, it necessary perform comparative seasonal dynamics