A unique relict lake is disappearing in Russia. Why is it threatened by common blue-green algae?


The relict lake on Kildin Island has unique flora and fauna. many species of animals living here are not found anywhere else. It is separated from the Barents Sea, and there is practically no water circulation in it. However, the lake may disappear, and in the near future.

A giant rock, which is located near the Barents Sea, Kildin Island is a fantastic mystery of nature. In this place, everything is remarkable, starting with the inhabitants, names, history of the development of mankind, geology, flora and the relict lake Mogilnoe.

The unique lake on Kildin Island was separated from the Barents Sea as a result of tectonic processes. It consists of several layers of water: the lower one is a dead zone with all the destructive hydrogen sulfide, the upper one is a natural source of fresh water.

The central part of the reservoir is filled with salt water and various marine inhabitants. The middle tier is inhabited by the rarest endemic fish — the Kildin cod, which is protected by the Red Book of Russia

Hydrochemical balance between salt and fresh layers

The inhabitants of the waters inhabit only the first 3 layers. Tansy and crustaceans are found in the upper layer. Jellyfish, crustaceans and cod live below. Purple bacteria settled in highly salted water, intensively releasing hydrogen sulfide to the lowest «dead» layer.

The marine «aquarium» is just over 16 meters deep. At the same time, the inhabitants never go beyond the boundaries of their layer and do not move to others.

Today, there is a deterioration in the state of the ecosystem of the relict sea in the Barents Sea. It is caused by increased overgrowth of blue-green algae (or cyanobacteria).


They grow most intensively in the salty water layer.

For the sea, the ingress of such harmful substances does not have negative consequences. However, a closed system remains in the relict lake. If foreign substances get into it, the composition of the water changes dramatically.

High content of cyanobacteria in surface waters

Unfortunately, it is hardly possible to save the lake. Due to human activities, blue-green algae bloom more and more and destroy the ecosystem of the reservoir. To stop this, it is necessary to completely ban construction near the lake, which the companies will definitely not want.