A palaeolimnological investigation at Crazy Well Pool, Dartmoor

This report presents the results from a short sediment core taken at Crazy Well Pool, Dartmoor. In addition to physical sediment analysis (loss on ignition and dry weights), siliceous microfossils (diatoms) have been used in an attempt to reconstruct lake pH changes and other water quality parameters. The core has also been dated using a technique based on the concentration of spheroidal carbonaceous particles (SCPs). The core showed a reliable chronology spanning in excess of 150 years and the diatoms were well persevered. A total of 65 species of diatom were recorded. A notable switch from benthic taxa at the base of the core to more planktonic species towards the core top was observed. Diatom pH reconstructions inferred that the lake has become slightly less acid over a post-industrial timescale, which is contrary to many other studies of UK lakes on base-poor geology. These results suggest that changes in catchment management have resulted in pH increases in the lake, despite evidence of acid deposition at the site. Information on diatom habitat requirements also suggests that lake levels have been lower in the past.