A multi-proxy study of lake-development in response to catchment changes during the Holocene at Lochnagar, north-east Scotland

This paper describes a multi-core lake sediment study using pollen, diatoms, and chironomids, together with magnetics and sediment biogeochemistry, as biotic and abiotic proxies to infer lake development in response to environmental change during the Holocene at Lochnagar in the eastern Highlands of Scotland. Diatoms are used to infer pH, chironomids to infer temperature, with pollen and plant megafossils acting as an independent proxy to validate these records and to provide insights into changes in catchment vegetation and soils. Lipid biomarkers are explored for their potential to provide additional information on lake productivity. The results indicate highly distinctive fluctuations in the loss-on-ignition (LOI) record, which are in phase with changes in some biotic (chironomid head-capsule concentration) and abiotic (coarse silt particle size fraction, and lipid and chlorine fractions) variables. Catchment-driven changes due to the development and degredation of soils, and the natural succession and human intervention on terrestrial catchment vegetation have the strongest influence on the diatom and chironomid assemblages. These catchment processes resulted in the natural acidification of the lake water. Post-industrial acidification of the lake was also influential on the lake biota. Climate-driven temperature change appears to have had only a weak influence on the biota with declines in cold stenothermic chironomid taxa in response to Early Holocene warming and declines in thermophilic chironomids in response to cooling at about 2600 cal. yr BP.