Shabla Tuzla is a natural brackish lagoon with an open water area of 24.4 ha. The reservoir is separated from the sea by about 80 m wide sandy hair, and here are the highest dunes on the northern Bulgarian Black Sea coast. It is a salt lake, formed mainly by the infiltration of salty seawater under the sand dunes. Its average depth is 0.6 m, its average salinity is 0.004.
Shabla Tuzla is an extremely important site in terms of nature protection. The wetland is part of the Shabla Lake Complex, included in the list of BirdLife International – Ornithologically important places / OVM / in Europe and Corine site according to the European program CORINE Biotopes with code F00008700. Lake “Shabla Tuzla” together with the protected area “Shabla Lake”, the adjacent agricultural lands and marine waters is an object of the European ecological network NATURA 2000 under the names “Shabla Lake Complex” / under Directive 79/409 / EEC for the protection of wild birds / and Lake Shabla – Ezerets ”/ under Directive 92/43 / ЕЕС for protection of natural habitats and wild flora and fauna/.
The origin and ecological characteristics of Tuzla show that this small lake is a unique coastal ecosystem with extremely rich flora and fauna. Located on one of the two primary waterways in Europe, Tuzla and its adjacent territories provide refuge to 198 species of birds / about 50% of the avifauna of Bulgaria /, recorded in all seasons.
41 species have been identified as nesting. Of these, the most important are the white-eyed grebe, the white-tailed deer, the brown-headed grebe, the stilt walker, the saber-beak, the sea rattlesnake, the evening kestrel, the Indian snipe, and the lark.
This is one of the most important reservoirs on the northern Bulgarian Black Sea coast, where large flocks of rainbirds stop for rest during their migration – a total of 28 species, forming clusters of hundreds of individuals. 16 species of seagulls and terns migrate through the territory of Tuzla, sometimes reaching several thousand specimens. 7 species of herons use the reservoir for rest, and the migration channels of 27 species of songbirds pass through the site annually. Representatives of the globally endangered small cormorant can also be observed in the complex.
For goose-like birds Shabla Tuzla is of major importance both during the migration period and during the winter. 25 species of waterfowl are marked on the territory of Tuzla, and especially important are the representatives of 3 globally endangered species – the thorny-tailed grebe – up to 3 specimens, the white-eyed grebe – up to 88 specimens, the red-breasted goose – up to 7,300 specimens. For the white-eyed diver, Tuzla is the reservoir with the highest concentrations on the northern Black Sea coast during migrations.
During the winter months, the mute swan forms clusters of up to 300 specimens, which makes the Tuzla one of the most important wintering grounds of this species in Bulgaria.
Despite its small size, Shabla Tuzla annually receives concentrations of over 20,000 waterfowl during the spring, autumn and winter months. The numbers of the mute swan, the great white-fronted goose and the red-breasted goose cover the threshold concentrations of the Ramsar Convention.
In addition to birds, this small wetland area has a prominent role to play in the conservation of other valuable fauna, such as the Syrian garlic and the otter. The significance of the site in conservation significance is complemented by some specific plant communities and the identified 13 species of rare and endangered plants included in the Red Book of Bulgaria.
Both the sea and fresh groundwater from the Sarmatian limestones participate in the water balance of the Shabla salt lake, the level of which comes to the surface here. For thousands of years, aquatic flora and fauna have contributed to the formation of healing mud with unique qualities. The great erosion susceptibility of the west coast provides the mud with the necessary amounts of fine-grained clay material. The reserves of healing mud amount to about 200,000 tons.