# Environmental Changes During the Late Glacial and Early Holocene Transition Revealed by Palaeolimnological Record from Southern Lithuania

## TL;DR

This study uses sediment analysis from Lithuania to reveal how climate changes affected the environment during the transition from the Late Glacial to the Early Holocene.

## Contribution

The study provides new insights into postglacial environmental dynamics in the southeastern Baltic region using multiple biotic proxies.

## Key findings

- Sedimentation began around 13,200–13,000 cal yr BP in a deep, oligotrophic palaeobasin.
- The Younger Dryas period was marked by high water transparency and oligo-mesotrophic conditions.
- A short-lived cooling event occurred around 9200–9000 cal yr BP during the Boreal period.

## Abstract

Currently, climate change has a significant impact on biodiversity. In order to accurately assess and predict the extent of these changes and the factors that caused them, as well as future trends, it is necessary to understand how these processes have unfolded over a longer period of time. This research focuses on the transition from the Late Glacial period to the Early Holocene, a period characterised by short-term and rapid climate changes similar to those occurring today. Three biotic proxies—Cladoceran, plant macrofossil and diatom analysis—are used in this study, which increases the reliability of the environmental reconstructions. Our results show that sedimentation started around 13,200–13,000 cal yr BP in a deep, oligotrophic palaeobasin. At about 13,000 cal yr BP, Allerød climatic warming influenced the shift to a shallow, ecologically diverse environment. During the Younger Dryas (12,850–11,650 cal yr BP), a rise in lake level and oligo-mesotrophic high water transparency conditions were fixed. At around 12,000 cal yr BP, climate warming and a drop in water levels were recorded. Intensive palaeobasin swamping processes began around 9700 cal yrs BP (Boreal).

This study presents integrated Cladoceran, plant macrofossil and diatom-based environmental reconstruction from the Čepkeliai Bog (Southern Lithuania), covering the Late Glacial–Early Holocene transition. The objective was to assess palaeoenvironmental changes with a focus on trophic state, acidification, and water-level fluctuations and to explore the applicability of these assemblages as temperature-sensitive indicators. The findings of our study revealed that sedimentation started at about 13,200–13,000 cal yr BP in a deep, oligotrophic and cold-water palaeobasin. Inferred palaeoenvironment changes correlate with the GI-1b event (Gertsenzee oscillation). A significant ecological shift to a shallow, warm, ecologically diverse environment occurredat about 13,000 cal yr BP and is consistent with the GI-1a (Allerød) period. The Younger Dryas (12,850–11,650 cal yr BP) is characterised by a rise in lake level and oligo-mesotrophic and high-water transparency conditions. At the end of the Younger Dryas (around 12,000 cal yr BP), climate warming and a drop in water levels were recorded. Intensive palaeobasin swamping processes began around 9700 years cal yr BP, during the Boreal period. A short-lived “9.2” cooling event was fixed at about 9200–9000 cal yr BP. The results obtained provide new insights into postglacial palaeoenvironmental dynamics in the southeastern Baltic region.