The Chironomidae of Grothusvatn, Sandoy, Faroe Islands: climatic and lake-phosphorus reconstructions, and the impact of human settlement

Chironomids were examined as part of a multiproxy palaeolimnological study of Grothusvatn, Sandoy, Faroe Islands. A total of 37 taxa was found in the top 1 m of the core. Chironomid-inferred total phosphorus and temperature reconstructions indicate that after landnam (the Norse settlement period) total phosphorus levels rose slightly, then peaked at a temperature minimum (interpreted as the 'Little Ice Age'). Total phosphorus levels subsequently fell to only slightly above pre-settlement levels at the sediment surface. Little indication of increased erosion in the catchment after landnam was found, and it is likely that the impacts of human settlement on Grothusvatn and its catchment were slight. We therefore propose that the temperature decrease caused the increase in the lake's productivity.