Sprecher
Beschreibung
Lake Sevan represents one of the most important freshwater ecosystems in the Caucasus region and serves as a unique center of biodiversity. Paleoenvironmental and palaeobotanical investigations from the Tsovinar-1 peat section reveal that Middle to Late Holocene lake-level fluctuations strongly influenced terrestrial and aquatic biodiversity in the region. Analyses of pollen, macro- and micro-plant remains, and fossil algae demonstrate that humid periods supported the development of forest vegetation, aquatic ecosystems, and extensive wetlands, whereas drier phases promoted the expansion of steppe communities and reduced aquatic habitats.
Pollen and carpological records document a diverse aquatic flora, including Nymphaea alba, Menyanthes trifoliata, Ceratophyllum, Potamogeton, and Myriophyllum, indicating a richer freshwater biodiversity than exists in the Sevan basin today. Fossil seeds of Menyanthes trifoliata and fruits of Ceratophyllum demersum var. platyacanthum, together with pollen of the relict tree Zelkova carpinifolia, confirm the former presence of these taxa in the region. However, these species are absent from the modern flora of the Lake Sevan basin, demonstrating substantial changes in biodiversity and ecosystem composition during the last 6000 years as a consequence of long-term climatic and environmental transformations.
The study also highlights the importance of fossil algae and cyanobacteria as bioindicators of ecological change. Taxa such as Pediastrum, Botryococcus, and Gloeotrichia reflect variations in lake level, trophic conditions, and water quality, providing valuable insights into long-term ecosystem evolution and emphasizing the importance of biodiversity conservation under ongoing climatic and anthropogenic pressures.
This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – 558487406.