Origin and Late Holocene evolution of Lake Morské oko in a climatic and environmental context in the Eastern Carpathians

Abstract

Palaeoecological reconstructions in the Carpathians have primarily focused on the western and south-eastern mountain ranges, leaving a significant gap in our understanding of the central region along the Slovak-Ukrainian borders. This study investigated Lake Morské oko (Vihorlat Mts., Eastern Slovakia), whose origin has been debated. Using a multiproxy approach that combines hydro-acoustic surveys, sedimentological analysis, biomarker-based organic geochemistry, and pollen analysis, we confirm that the lake formed when a landslide from the eastern slopes of Motrogon and Jedlinka hills dammed the Okna valley shortly before 2780 cal a BP, coinciding with a documented wet period across Europe. Our record reveals a remarkably stable lake system that evolved from being dominated by terrestrial organic input to enhanced in-lake production after 1850 cal a BP. Our quantitative temperature and humidity reconstructions, the first in the region, capture major climatic episodes, including the end of the “2.8 ka event”, Roman Warm Period, and Mediaeval Climate Anomaly, during which there was likely increased lake water thermal stratification or reduced connectivity with the catchment. The Little Ice Age period is marked by temperature fluctuations corresponding to the Maunder and Dalton minima. Human influence becomes evident from 1100 and 700 cal a BP through increased Cerealia-type pollen and atmospheric lead deposition from regional mining activities. This study provides a continuous, well-dated Late Holocene palaeoenvironmental record spanning nearly 3000 years from this region of the Carpathians, bridging a crucial gap between western and eastern records while definitively confirming the lake's origin from a landslide.