Classification, assessment and trophic reconstruction of Danish lakes using chironomids

Abstract

1. Surface‐sediment assemblages of subfossil chironomid head capsules from fifty‐four primarily shallow and nutrient‐rich Danish lakes were analysed using multivariate numerical techniques. The species data, comprising forty‐one chironomid taxa, were compared to environmental monitoring data in order to establish a relationship between chironomid faunal composition and lake trophic state. 2. The subfossil assemblages were compared to the chironomid bathymetric distributions along transects from four lakes. Correspondence analysis and similarity coefficients showed that the subfossil assemblages, sampled in the lake centre, reflect the chironomid communities in the littoral at a depth of 2–7 m. 3. Two‐way indicator species analysis (TWINSPAN) was used to classify the Danish lakes into five groups defined by trophic state, lake depth and pH. Eighteen chironomid taxa showed significant differences in abundance among the five groups. Canonical correspondence analysis (CCA) showed the chlorophyll a concentration ([Chl a]) and Secchi depth to be the variables best correlated to the faunal data, and fourteen taxa were significantly correlated to [Chl a]. 4. The strong correlation between chironomid data and the ln‐transformed ([Chl a]) was used to create a weighted averaging (WA) model to infer lake trophic state. Several models were tested by cross validation (leave‐one‐out jack‐knifing), and a simple WA model using inverse de‐shrinking had a RMSEPjack of 0.65 (ln units) and a r2jack of 0.67. 5. The results can be used in the assessment and reconstruction of lake trophic state for long‐term monitoring and palaeoecological investigations of shallow, temperate lakes in the mesotrophic to hypertrophic nutrient range.

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

“…The subfossil assemblages in Lake De Waay are most similar to the living invertebrate community in the littoral zone, between 0.8 and 3.2 m water depth. Similar results were found by Brodersen and Lindegaard (1999) who observed that the subfossil assemblages sampled in the lake centre reflected the chironomid communities in the littoral at a depth of 2-7 m in four Danish lakes.…”

“…Evidence for transport of chironomid remains to deeper sections of lakes was observed in shallow and continually mixing lakes (Iovino 1975;Hofmann 1986;Eggermont et al 2007;Holmes et al 2009) as well as in deeper, stratifying lakes (Wiederholm 1979;Schmäh 1993;Brodersen and Lindegaard 1999;Heiri 2004). In a survey of African crater lakes, more invertebrate taxa were recovered as subfossil remains from surface sediments than by collecting living invertebrates (Rumes et al 2005;Rumes 2010), which may also be the result of the limited spatial and temporal sampling of living invertebrates.…”

“…Temporal and spatial variation in the living assemblages may result from specific habitat preferences (Frey 1988;Hofmann 1988;Moog 2002). Later, diagenetic processes and transport may affect certain taxa more strongly than others (Walker et al 1984;Frey 1988;Brodersen and Lindegaard 1999;Eggermont et al 2007). For chironomids, it has been shown that different subfossil assemblages can be found in different locations within a lake basin (Schmäh 1993;Heiri 2004;Eggermont et al 2007;Kurek and Cwynar 2009a, b).…”

Fossil chironomid δ13C as a proxy for past methanogenic contribution to benthic food webs in lakes?

“…Consequently, fossil chironomid assemblages can be used to reconstruct the past chironomid fauna of lakes and infer past changes in physical and chemical variables from lake sediments. Examples of chironomid-based environmental inferences include the reconstruction of air or water temperature (Walker and Cwynar 2006;Brooks 2006;Heiri et al 2007), total phosphorus (Brooks et al 2001;Langdon et al 2006), chlorophyll a (Brodersen and Lindegaard 1999), oxygen availability (Quinlan et al 1998), and lake depth (Korhola et al 2000). Recently, the potential of fossil chironomids for isotope studies has been demonstrated with regard to 14 C dating (Jones et al 1993;Fallu et al 2004) and to d 18 O as a palaeotemperature proxy (Wooller et al 2004.…”

Holocene subfossil chironomid stratigraphy (Diptera: Chironomidae) in the sediment of Plešné Lake (the Bohemian Forest, Czech Republic): Palaeoenvironmental implications

“…As a result of their short generation times and the dispersal capacity of the winged adults, chironomids respond rapidly to changes in a wide variety of environmental variables (Walker, 2001). Transfer functions have been developed for a range of environmental parameters including salinity (Heinrichs et al, 2001), dissolved oxygen (Quinlan & Smol, 2002) and nutrients (Brodersen & Lindegaard, 1999;; however, over large climatic gradients, air temperature is often the best explanatory variable for chironomid distribution Walker et al, 1997;Brooks & Birks, 2000). Chironomid larvae possess chitinized head capsules that are resistant to decomposition.…”