Gefährdete Armleuchteralgen in der Schweiz: Chara filiformis H. Hertzsch und Nitella tenuissima (Desv.) Kütz.

Endangered Charophytes in Switzerland: Chara filiformis H. Hertzsch und Nitella tenuissima (Desv.) Kütz. Charophytes are macrophytic green algae represented by 25 species in Switzerland, 21 of which are listed as endangered on the Red List of Charophytes of Switzerland. New sites of Chara filiformis H. Hertzsch and Nitella tenuissima (Desv.) Kütz., both highly endangered species, were discovered during field campaigns by the canton Zurich in Summer 2022–24. Chara filiformis is currently found in only five lakes in Switzerland. In Lake Zurich they were rediscovered at a site where the species was previously recorded approximately 100 years ago, but since then it has never been found again. Due to the re-oligotrophication in Lake Zurich, the species was able to re-establish itself in less competitive localities within the littoral zone. Nitella tenuissima is very rare in Switzerland and is currently known only from two sites. The species was recorded in small waterbodies within the wet meadows of the Husemersee and in the floodplain of the river Thurin the canton of Zurich. Cantonal action plans for resettlement of both Characeae have been developed.