Chironomid-based inference models for estimating mean July air temperature and water depth from lakes in Yakutia, northeastern Russia

Abstract

We investigated the subfossil chironomid fauna of 150 lakes situated in Yakutia, northeastern Russia. The objective of this study was to assess the relationship between chironomid assemblage composition and the environment and to develop chironomid inference models for quantifying past regional climate and environmental changes in this poorly investigated area of northern Russia. The environmental data and sediment samples for chironomid analysis were collected in 5 consecutive years, [2003][2004][2005][2006][2007], from several regions of Yakutia. The lakes spanned wide latitudinal and longitudinal ranges and were distributed through several environmental zones (arctic tundra, typical tundra, steppetundra, boreal coniferous forest), but all were situated within the zone of continuous permafrost. Mean July temperature (T July ) varied from 3.4°C in the Laptev Sea region to 18.8°C in central Yakutia near Yakutsk. Water depth (WD) varied from 0.1 to 17.1 m. T July and WD were identified as the strongest predictor variables explaining the chironomid communitiy composition and distribution of the taxa in our data set. Quantitative transfer functions were developed using two unimodal regression calibration techniques: simple weighted averaging (WA) and weighted averaging partial least squares (WA-PLS). The two-component T July WA-PLS model had the best performance. It produced a strong coefficient of determination (r 2 boot = 0.87), root mean square error of prediction (RMSEP = 1.93), and max bias (max bias boot = 2.17). For WD, the one-component WA-PLS model had the best performance (r 2 boot = 0.62, RMSEP = 0.35, max bias boot = 0.47).

Holocene climate conditions in central Yakutia (Eastern Siberia) inferred from sediment composition and fossil chironomids of Lake Temje

“…Micropsectra insignilobus-type and Pseudochironomus appear for the first time, with abundances above 5%, in this zone only. The cold stenotherm M. insignilobus-type appears in the middle of the zone, and Pseudochironomus, an indicator of relatively warm conditions, low total phosphorus and high Secchi depth (Brooks et al, 2007;Nazarova et al, 2011) is recorded in the top four analysed horizons of the zone. The concentration of chironomids HC varies widely throughout this zone.…”

“…The specific aim is to provide reconstructions of mean July air temperature (T July ) and water depth (WD) during the last 10,000 years, using the newly developed chironomid-inferred mean July temperature and water depth model published by Nazarova et al (2011). In addition, the depositional boundary conditions of the lake development are revealed by sedimentological data.…”

Oxygen isotope composition of diatoms as Late Holocene climate proxy at Two-Yurts Lake, Central Kamchatka, Russia

“…4 and 6). The used transfer function was inferred from modern chironomid training data sets from lakes of eastern Siberia (Nazarova et al 2008(Nazarova et al , 2011. The chironomid-based T air July exhibit a threefold pattern of change with colder intervals (~12-13°C) before about 3.9 kyr BP and after about 1.2 kyr BP.…”

Modern and Fossil Diatom Assemblages from Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Siberia)

“…The study material included water samples and the samples of superficial benthic sediments consisting of silty or sandy matter with some detritus. We measured water temperature, pH, and conductivity (Wetterich еt al., 2009 a;Nazarova et al, 2011). The chemical composition of water was hydrocarbonate-chloride (Wetterich et al, 2008) with a low mineralization rate (Alekin, 1970) and low hardness.…”