| الوصف: |
The Durankulak Lake is the northernmost Bulgarian Black Sea lagoon. The hydrological regime of the lake is, for the most part, the inflow of water in karst underground cracks. Over the years, the rare cases of digging a sea-lake canal have been a significant cause of the oligohaline estuarine wetlands nature of the water body. The publication aims to present current research on the structure of the lake bottom, the heart of the substrate and changes over the years, using data from a multi-beam echo sounder and side-scan sonar, as well as new data for ichthyological fauna. In the period 2020-2021, the lake was monitored, including key physicochemical indicators, which indicate an increase in the period of eutrophication due to changes in climatic conditions and the impact of anthropogenic pressure. The average salinity of lake waters is approximately 2 ppm salinity, with a maximum at the end of summer - 4 ppm salinity and a minimum in spring - 1 ppm salinity. The average data of the other physicochemical indicators are the following: T�C-13.5, pH-8.48, O2 ml/ - 7.52 for the period 2019 - 2021. The hydrological and hydromorphological features of Durankulak Lake are crucial for the composition of its fish fauna, which is mainly composed of freshwater and brackish forms. The fish that inhabit the year-round Durankulak Lake belong to several faunal complexes. In the first place is the complex of primary freshwater, which is represented by nine species belonging to the families Cyprinidae (6 species), Siluridae (1 species), Gasterosteidae (1 species) and Gobiidae (4 species). The group of Mediterranean immigrants, represented by only one species of the family Syngnathidae, is the least represented. |
