Late Quaternary palaeoenvironmental change in the northeastern Mediterranean: a diatom-based reconstruction from lacustrine sediments

Seymour-Jones, Robyn Francesca

Abstract

Much of our understanding of Quaternary palaeoenvironmental change has been generated from long, continuous marine sediment and ice core sequences. These records span multiple glacial–interglacial cycles, providing an essential long-term perspective on natural climate variability that sets the context for recent anthropogenic climate change. However, to develop resilience to future climatic changes, it is crucial to understand the manifestation of global climatic change over terrestrial regions and the environmental response to such changes. This is especially critical in hydrologically sensitive, semi-arid regions such as the northeastern Mediterranean, where anthropogenic climate change is already having a detrimental impact on water security. This region is remarkable for its high density of ancient lakes, and long sediment cores of good stratigraphic continuity have been recovered from Lake Ioannina (Greece) and Lake Ohrid (North Macedonia/Albania). These have been used to produce reconstructions of environmental change spanning multiple glacial–interglacial cycles.
This thesis generates new diatom assemblage records from these two lakes to fill the gap in our knowledge about MIS 7–9, an interval of particular interest given the relatively weak glacial–interglacial changes at this time. These lakes are only c. 150 km apart, so are subject to the same climatic forcing, but shallow, eutrophic Lake Ioannina experiences significant lake-level fluctuations, while deep, oligotrophic Lake Ohrid is renowned for its long-term stability. By comparing the diatom assemblages of these two lakes and their differing response to the same climatic forcing, changes in hydroclimate and temperature can be better disentangled. Meanwhile, existing palynological and geochemical data enable the separation of the palaeoclimate signal from other drivers of limnological change.
The results reveal a diatom response at Lake Ioannina that is driven by variations in lake level and mixing regime and is remarkably subtle, with the persistence of a relatively deep lake throughout most of MIS 7–9. In contrast, the response at Lake Ohrid during MIS 7 reflects temperature changes, which become more variable on the approach towards the penultimate glacial inception.

Citation

Seymour-Jones, R. F. Late Quaternary palaeoenvironmental change in the northeastern Mediterranean: a diatom-based reconstruction from lacustrine sediments. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4749956

• Thesis Type: Thesis
• Deposit Date: Jul 31, 2024
• Publicly Available Date: Jul 31, 2024
• Keywords: Physical geography
• Public URL: https://hull-repository.worktribe.com/output/4749956
• Additional Information: Department of Geography, Geology and Environment; University of Hull
• Award Date: Jan 1, 2022