The Sava Lake – charophyte gem in the heart of Belgrade

The Sava Lake, originating from a branch of the Sava river, is situated next to the island Ada Ciganlija on the right bank of the Sava river in Belgrade (Serbia). It is an urban recreational lake under strong anthropogenic influence, especially during the summer days. Investigations of aquatic vegetation were conducted several times during the last decades and the latest systematic survey was conducted in summer 2017 as a part of STARWALK project. Since then, sampling was continued sporadically, revealing a great diversity of charophyte algae. Overall,we discovered eight charophyte species in the lake, which is a remarkable number even for unimpacted natural lakes. The species found belong to four out of six genera of living charophytes. The genus Chara is represented with three species, C. globularis, C. contraria and C. virgata, the genus Nitella also with three, Nitella mucronata, N. gracilis, N. flexilis, and genera Tolypella and Nitellopsis with one species, respectively, T. intricata and N. obtusa. Moreover, almost all discovered species are red listed in Serbia and the Balkans, according to IUCN criteria. Six of them are strictly protected according to national legislation. The finding of Nitella flexilis was the first finding of this species for Serbia