Changes in the composition of the spring zooplankton of Lake Baikal

Аннотация

Since the 60s of the past century, researchers from Limnological Institute SB RAS have been regularly sampling zooplankton in a network of stationary stations along the Baikal water areas. In 2009-2018, the samples were collected in late May or early June immediately after the melting of ice during the complex expedition. The total biomass and abundance of zooplankton did not go beyond the interannual fluctuations observed in the 60-90s of the past century. A high abundance of spring rotifers in the Middle and Southern basins was also observed in 2015-2018. In the northern basin, the maximum rotifers indicator for the entire period of 30% of the plankton abundance was recorded only in 2016. The amount and composition of organisms in the surface layer depend on many factors. In our opinion, the depth and temperature characteristics of the water layer play an important role. The change in the heating and mixing of water could have led to observed shifts in the surface plankton composition.