Chironomid-based Holocene summer temperature variability in Lake Prokoško, Vranica Mountains, Bosnia and Hercegovina (western-Balkan region)

Despite increasing regional studies, quantitative reconstructions of Holocene climate remain limited in the western Balkans. This study provides the first chironomid-based summer air temperature reconstruction from Bosnia and Herzegovina, based on a sediment core from Lake Prokoško (1670 m a.s.l., Vranica Mountains) spanning ∼11,700 cal yr BP to the present. In total, 53 chironomid taxa were identified, with assemblage changes reflecting major ecological and climatic shifts. Cold-adapted Late Glacial taxa persisted until ∼11,500 cal yr BP, after which warmer and more stable conditions promoted oligotrophic to mesotrophic assemblages and the rise of Cladotanytarsus mancus -type, accompanied by July air temperatures reaching ∼13.2 °C (based on Swiss-Norwegian training set results). Later drop in temperatures ∼8000 cal yr BP to 11.2 °C could be connected to the 8.2 ka climatic oscillation. The Middle Holocene transition (∼6000–5500 cal yr BP) shows cooling to 11.8 °C, reduced taxonomic richness, and enhanced sediment input. The reconstructed July air temperatures from this interval may have been partly influenced by human impact. From ∼5000 cal yr BP, mesotrophic conditions and higher diversity prevailed, with temperatures fluctuating between ∼12.0 and 13.3 °C. Late Holocene oscillations include an increase to 13.4 °C at ∼3500 cal yr BP and a decrease to 12.0 °C at ∼2480 cal yr BP, followed by warming during the Roman Warm Period (∼13.3 °C, ∼2000 cal yr BP). The past millennium shows strong anthropogenic influence, with increased representation of meso-to eutrophic taxa, macrophyte expansion, and reduced oxygenation of the profundal zone. Comparisons with other European mountain lakes indicate broadly coherent Holocene climate trends, providing this record as a key reference for the western Balkans.