The Srebarna Lake was designated as a Monument of World Cultural and Natural Heritage (1983), UNESCO biosphere reserve (1977), Ramsar site (1975) and Important Bird Area (1990) because of its extremely rich ornithofauna and mainly because of the breeding of globally threatened species Dalmatian Pelican (Pelecanus crispus), Pygmy Cormorant (Phalacrocorax pygmeus) and Ferruginous Duck (Aythya nyroca). During the last years the lake ecosystem underwent significant changes towards strong eutrophication and anthropogenically speeded-up succession. The main reasons were the interrupted connection with the Danube River (because of a dyke built in 1948) together with the pumping-out of the underground waters, as well as the agricultural changes and activities in the watershed basin. The restoration activities carried out in 1993-1994 and especially the canal which connected the lake with the Danube lead to the beginning of lake recovery. All these events influenced the biodiversity of the reserve.

The dominant plant association is that of the Reed (Phragmites australis), which occupies about two-thirds (400 ha) of the Reserve's total surface area. Gray Willow (Salix cinerea) and Purple Willow (Salix purpurea) bushes grow in some places. The second widest spread plant species after the Reed is the Lesser Reedmace (Typha angustifolia), and it is more abundant than the Great Reedmace (Typha latifolia). Of all 139 vascular plant species hosted by the Reserve, 11 are rare or endangered. Some 19 fish species occurred in the lake until 1948. There are 21 reptile and amphibian species, and 41 mammal species. The avifauna numbered a total of 230 bird species. The nesting colony of Dalmatian Pelican (Pelecanus crispus) is the pearl of the Reserve.