The Kosinskie Lakes are the only natural reservoirs of glacial origin on the territory of Moscow that are part of the natural and historical Kosinski park. Moreover, they are a natural landmark. Therefore, they need to be studied thoroughly and attentively. The ecological situation of the area is quite controversial. The lake drainage area suffers a great anthropogenic load. According to the calculation results of the Mayer index in 2018, the situation has worsened compared to 2017. There is a decrease in biodiversity of hydrobionts of the Kosinskie Lakes, as well as a decrease in the number of types of indicators used in the calculation of the Mayer index. The Lakes Beloe, Svyatoe and Chernoe refer to polysaprobic water bodies. The massive development of saprotrophic organisms is most likely caused by sharply increased eutrophication of the Kosinskie Lakes as they now locate on the territory of Moscow. Besides, the area nearby the Kosinskie Lakes is extensively used for mass

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