Subfossil chironomid assemblages in deep, stratified European lakes: relationships with temperature, trophic state and oxygen

Abstract

1. The distributions of subfossil remains of chironomid larvae in 28 large, deep and stratified lakes in Europe were examined in surface sediments along a latitudinal transect ranging from northern Sweden to southern Italy. 2. Canonical correspondence analysis (CCA) showed that summer surface water and July air temperature, as well as total phosphorus (TP) concentrations, hypolimnetic oxygen availability and conductivity were statistically significant (P < 0.05) explanatory variables explaining between 11 and 14% of the variance in the chironomid data. 3. Owing to the spatial scale covered by our study, many environmental variables were covarying. Temperature, TP concentration and oxygen availability were positively or negatively correlated with the first axis of a detrended correspondence analysis (DCA) of chironomid assemblages, suggesting that climatic and trophic conditions influenced profundal chironomid assemblages either in a direct (food and oxygen) or in an indirect (temperature) way. Parameters related to local environmental conditions, lake morphology and bedrock geology, such as organic matter content of the sediment, maximum lake depth, Secchi depth and pH, were not significant in explaining the distribution of chironomid assemblages in our study lakes. 4. The strong relationship between chironomid assemblages and summer temperature may be related to the covariation of temperature with parameters, such as nutrient and oxygen availability, known to affect chironomid assemblages in deep, stratified lakes. However, summer temperature explained a statistically significant proportion of the variance in the chironomid assemblages even when effects of oxygen availability and TP concentrations were partialled out. This suggests that summer temperature has an effect on chironomid assemblages in deep lakes, which is not related to its covariation with trophic state. 5. The potential of fossil chironomid analysis for quantitatively reconstructing past nutrient conditions in deep, stratified lakes was examined by calculating the Benthic Quality Index (BQI) based on subfossil chironomids and by comparing BQI values with observed TP concentrations. BQI was linearly related to log-transformed TP. Applying this relationship to fossil chironomid assemblages from Lake Päijänne (Finland) produced a TP reconstruction in agreement with measured TP during the period 1970-1990, demonstrating that this approach can provide quantitative estimates of past nutrient concentrations in deep, stratified lakes.

How representative are subfossil assemblages of Chironomidae and common benthic invertebrates for the living fauna of Lake De Waay, the Netherlands?

“…Of these groups, the chironomids are one of the most abundant benthic macroinvertebrate groups in aquatic ecosystems (Pinder 1995) and have increasingly attracted attention in palaeolimnology over the past two decades. Their larval head capsules often occur in high abundances in sediments and have been used to reconstruct a range of environmental variables such as temperature Ilyashuk et al 2009), lake trophic status (Lotter et al 1998;Langdon et al 2006), water depth (Korhola et al 2000;Kurek and Cwynar 2009a), and oxygen availability (Quinlan and Smol 2001a;Heiri and Lotter 2003;Verbruggen et al 2010).…”

Strengths and Weaknesses of Quantitative Climate Reconstructions Based on Late-Quaternary Biological Proxies

“…For example, it is very likely that the strong relationship observed between chironomid assemblages and summer temperature is mediated and reinforced to a significant extent by climate effects on water chemistry parameters (e.g. nutrient and oxygen concentrations) (Brodersen & Quinlan 2006;Velle et al 2010;Verbruggen et al 2010). If, in modern training sets, these water chemistry parameters are affected in parts of the gradient by processes unrelated to climate, such as human activity or acidification, it is possible that WA-PLS will correct for any resulting offset in inferred values within a developed chironomid-based calibration function for temperature.…”

An extended Benthic Quality Index for assessment of lake profundal macroinvertebrates: addition of indicator taxa by multivariate ordination and weighted averaging

“…The BQI is well suited for such assessment because it can be interpreted as measuring the community characteristics, 'ratio of disturbancesensitive taxa to insensitive taxa' and 'taxonomic composition,' included in the normative definitions of ecological status by the WFD (Jyväsjärvi et al 2010). The strong response of BQI to increasing and decreasing human disturbance has been well documented in contemporary (Rask et al 2011, Jyväsjärvi et al 2012) and palaeolimnological (Ilyashuk et al 2003, Meriläinen et al 2003, Hynynen et al 2004, Verbruggen et al 2011) studies. Another advantage of BQI for modern reference-condition-based assessments (Bailey et al 2004, Stoddard et al 2006) is that its sitespecific reference value can be predicted reliably from environmental variables (Jyväsjärvi et al 2010).…”

“…The chironomid BQI has been widely adopted in Europe as a profundal habitat-monitoring tool (Gerstmeier 1989, Kansanen et al 1990, Johnson 1998, Hämäläinen et al 2003, Raunio et al 2007, Verbruggen et al 2011. BQI also has been used provisionally as a metric in Swedish ( Johnson and Goedkoop 2007) and Finnish (Rask et al 2011, Jyväsjärvi et al 2012) bioassessments of lakes mandated by the Water Framework Directive of the European Union (European Commission 2000).…”