The relationship between water and air temperature in chironomid-based paleoclimate reconstructions: Records from boreal and subarctic Finland

Abstract

Fossil remains of larval chironomids are one of the most useful paleolimnological proxies to reconstruct Holocene paleoclimate. We investigate the within-lake distribution of chironomids in relation to water temperature and test the usability of intralake calibration in chironomid-based temperature reconstructions. We compare our findings against the traditional multilake calibration technique in Holocene sediment cores from Finland. The results show that intralake water temperature optima of common taxa correspond closely with mean July air temperature optima in a regional multilake dataset, with exception of a few vegetation-associated taxa. A calibration model based on intralake water temperatures shows performance statistics that correspond to the general performance statistics level of multilake calibration models. However, the intralake model has somewhat increased prediction error. Despite the fact that the intralake model is sensitive to poor modern analogues, it shows correlation with the results using the multilake calibration approach in the Holocene reconstructions. Our results confirm that the within-lake distribution of chironomids along a water depth gradient is closely linked with water temperature gradient. This provides evidence for the close relationship between chironomids and temperature in general and suggests that, in addition to the regional scale, water temperature is a key variable in determining chironomid distribution at the site-specific scale. However, long-term changes in intralake gradients in other depth-related factors, such as hypolimnetic oxygen conditions, extent of photic zone and habitat distribution, may hamper the quantitative accuracy of chironomid-based temperature reconstructions, though the results also suggest that these changes are likely to have little general impact on the trends of chironomid-based air temperature reconstructions.

Response of Lacustrine Biota to Late Holocene Climate and Environmental Conditions in Northernmost Ungava (Canada)

“…É. SAULNIER-TALBOT et al NIER-TALBOT et al Overall, we found evidence for reliable chironomidbased inferences of temperature trends for the region, especially from the two headwater lakes. �hese findings are consistent with the well-established relationships between chironomids and both air and water temperature at high latitudes (Brodersen and Lindegaard, 1999;Luoto et al, 2014). Indeed, many studies have illustrated the accuracy of using chironomids for quantitatively reconstructing air temperature.…”

A 2000-year record of lake ontogeny and climate variability from the north-eastern European Russian Arctic

“…A major factor influencing chironomid communities is lake-level changes (Engels and Cwynar, 2011) that could potentially compromise the reliability of the reconstruction. However, a study on boreal lakes has shown that since the inlake water depth gradient is usually directly linked with the water temperature profile, it has the same control on chironomid distribution as the air temperature gradient at large spatial gradients (Luoto et al, 2014). In addition to hydrological conditions, dissolved organic carbon (DOC) and lake humic state have significant influence on chironomid communities (Larocque et al, 2006; Luoto, 2013).…”

Disentangling the Evidence of Milankovitch Forcing From Tree-Ring and Sedimentary Records

“…In the study region, discrepancies between the pollen and other sedimentary proxy records have recently been related to inaccuracies in the models transforming the pollen data into temperature estimates, to climatic disequilibrium of vegetation migration patterns, and to site-specific factors (Luoto et al, 2014b;Shala et al, 2017). Chironomid-based records, however, may be affected by limnic factors (Luoto et al, 2014a).…”