Доклади на Българската академия на науките Comptes rendus de l’Acad´ emie bulgare des Sciences Tome 66, No 3, 2013 BIOLOGIE Botanique PALAEOECOLOGY AND GEOARCHAEOLOGY OF VARNA LAKE, NORTHEASTERN BULGARIA Mariana Filipova-Marinova, Danail Pavlov * , Stoyan Vergiev, Vladimir Slavchev ** , Liviu Giosan *** (Submitted by Academician V. Golemansky on October 30, 2012 ) Abstract Palaeoenvironmental data from the high-resolution spore-pollen analysis of laminated sediments from newly-taken Core 3 – Varna Lake were combined with analyses of dinoflagellate cysts, acritarchs and other non-pollen palynomorphs (NPP), including fossil algal and fungal remains. The location of the core is close to submerged prehistorical sites and permits the palaeoenvironmental cor- relations of obtained results with available archaeological and geochronological data. The established Age Model shows that the accumulation of lake sed- iments started after 7870 cal. BP and is connected with a rise of the Black Sea level. One-hundred-ninety-cm-long molluskan shell hash layer of Mytilus galloprovincialis covers the interval from 7776 to 6183 cal. BP. The mixed oak and hornbeam forests dominated the vegetation cover during the Atlantic, Sub- boreal and Subatlantic chronozones of the Holocene. An important change in the forest composition occurred at ca 5598 cal. BP, when Carpinus betulus increased its spreading due to climatic changes. The high-resolution recon- struction of palaeovegetation also reveals the extent of anthropogenic influence in Varna Lake area. Two periods of significant presence of pollen from culti- vated cereals, weeds and ruderals were identified. According to the available AMS-radiocarbon data, these periods are attributed to the Late Eneolithic and Early Bronze Age. The anthropogenic impact on the natural vegetation has been identified by deforestation and agricultural practice. The Transitional pe- riod without human activities between these two periods lasted ca 319 years The financial support of the bilateral project “Comparative PaleoEcology and GeoArchaeol- ogy of Varna Lake (Bulgaria) and Mamaia Lake (Romania) – E.G.A.L.” funded by the Bulgarian National Science Fund and the Romanian National Authority for Scientific Research is greatly acknowledged. 377