In the Nadym district of the Yamalo-Nenets Autonomous Okrug, there are so-called "blue lakes". Located in the north-taiga, they are interesting not only for their unusual bright blue color, but also for their peculiar cone hollow with a depth of up to 12 m, the chemical composition of ultra-fresh waters, and the almost complete absence of fish. The flora and fauna of anomalous lakes have not been studied yet, and geological research data is very limited.
Assessing the status of bodies of water is often connected to the analysis of zooplankton -- small animals drifting with the water flow. Such creatures are invisible to the eye, but annually they pass through themselves a volume of water approximately equal to the volume of the World Ocean, furthermore, many aquatic animals feed on them. Thus, it is not surprising that changes occurring with zooplankton are reflected in the state of the entire water reservoir.
Scientists from Tyumen State University studied the variety of species, the abundance, and biomass of zooplankton of the two blue lakes. To do so, they collected animals by filtering water through a special sieve, then they determined the main chemical characteristics, including the content of heavy metals (iron, copper, nickel, and others), analyzed the abundance and the diversity of species of zooplankton. The species composition was represented by 14 different species of organisms, while the similarity index was only 38%. Discovered species are typical for most bodies of water in Western Siberia -- these are cladocerans and copepods, rotifers. The most numerous and constantly appearing species is the crustacean Sida crystalline. Another species, copepod ?nthocyclops vernalis, is considered quite rare in lakes of such type. Notably, the concentration of some heavy metals exceeded the sanitary and hygienic standards, although this feature is characteristic to many bodies of water in the region and is associated with the abundance of swamps and processes in the soil.
"The zooplankton of the examined lakes is very similar to the zooplankton of other reservoirs in the Yamalo-Nenets Autonomous Okrug. Since water invertebrates are good indicators of water quality, the obtained data can be further used for the integrated environmental monitoring of the region's aquatic ecosystems", - comments Andrey Soromotin, doctor of biological sciences, professor, director of the Institute of Ecology and Rational Use of Natural Resources of Tyumen State University, honored ecologist of the Russian Federation, a Fellow Member of the Russian Academy of Natural Sciences