Impact of early prehistoric farming on chironomid communities in northwest Ireland

• Published in: Journal of paleolimnology 2017-03, Vol.57 (3), p.227-244
• Main Authors: Taylor, Karen J., Potito, Aaron P., Beilman, David W., Ghilardi, Beatrice, O’Connell, Michael
• Format: Article
• Language: English
• Subjects: Autecology; Bronze Age; Charcoal; Chironomidae; Climate Change; Diptera; Earth and Environmental Science; Earth Sciences; Environmental impact; Eutrophication; Farming; Freshwater; Freshwater & Marine Ecology; Freshwater lakes; Geochemistry; Geology; Grasslands; Insects; Lake sediments; Original Paper; Paleolimnology; Paleontology; Pastoralism; Pasture; Physical Geography; Pollen; Sedimentology
• ISSN: 0921-2728; 1573-0417
• DOI: 10.1007/s10933-017-9942-6

This study explored the utility and performance of chironomid (Diptera: Chironomidae) autecology in the investigation of prehistoric farming impacts on freshwater lake systems. Chironomid subfossils, lake sediment geochemistry (δ 13 C, δ 15 N and C:N), pollen and macroscopic charcoal analyses were used in a comparative limnological assessment of three archaeologically rich study sites in northwest Ireland. At all three study sites, pastoral farming and its associated nutrient inputs, as represented by non-arboreal pollen indicative of grassland/pasture (NAPp) and lake sediment geochemistry, are concomitant with increases in eutrophic chironomid taxa. Redundancy analysis (RDA) and partial RDAs established that δ 15 N and NAPp were controlling factors of chironomid community compositional change during the Neolithic (4000–2500 BC) and Bronze Age (2500–600 BC). Bronze Age farming had a considerably greater impact on the lake systems than Neolithic farming, as indicated by a higher proportion of eutrophic taxa and increases in δ 15 N, C:N and δ 13 C values, consistent with increased erosion and agricultural inputs. Findings emphasise the importance of identifying the natural, pre-impacted state of a lake system to determine the extent of agricultural impact accurately. The timing and magnitude of change show that Neolithic and Bronze Age farming exhibited a strong control over chironomid communities at all three sites.