Microscopic algae blooms coloured the waters of the sea and Varna Lake

The sea water in the area of Aparuhovo beach in Bulgaria's Black Sea coastal city of Varna turned red-brown.

The same hue has also appeared in the waters of Varna Lake.

Local residents alerted the authorities via the emergency number 112, and the signal was forwarded to all relevant institutions.

“We haven’t seen such an occurrence at this time of year,” worried fishermen told BNT's morning programme "The Day Begins" on March 11.

All institutions responsible, either directly or indirectly, for water cleanliness have taken samples.

Among them are the staff of the Institute of Oceanology. They already have initial data from the samples they have taken.

Specialists identified the presence of two types of microscopic algae, which are responsible for the characteristic reddish colouring of the sea water in the examined areas.

Algal blooms are common at this time of year due to the enrichment of the water with nitrogen, phosphorus, and other nutrients, as well as local anthropogenic pressure from Varna Lake.

“Two samples were taken – one from the canal waters and the other from the sea waters at the beach,” commented Yavor Dimitrov, Director of the Black Sea Basin Directorate.