Chironomid stratigraphy in the shallow and eutrophic Lake Søbygaard, Denmark: chironomid–macrophyte co‐occurrence

Abstract

1. A sediment core from the shallow, hypertrophic Lake Søbygaard (mean depth ∼1 m; [TP] 310 μg P L−1) was analysed for subfossil remains to reconstruct chironomid community changes in relation to the succession and disappearance of aquatic macrophytes. 2. Species composition in the 1.10 m core indicates a succession from a ‘naturally’ eutrophic state to a hypertrophic state during recent centuries. Radiometric dating (210Pb) of the uppermost 20 cm of the sediment core (∼1932–93) indicates that sediment accumulation rate had doubled in recent decades. 3. Changes in chironomid assemblages were in close agreement with changes in both diatoms and macrophyte remains in the same core. Distinct changes in chironomid communities reflect the eutrophication process and macrophyte succession through Chara, Ceratophyllum and Potamogeton dominance to the present state, with complete loss of submerged vegetation and dominance by phytoplankton. 4. The co‐occurrence and relationship between aquatic macrophyte diversity and recent subfossil chironomid assemblages were assessed from an additional 25 Danish lakes. There was good agreement between the macrophyte and chironomid‐based lake groupings. Overall, a significant difference (P<0.001) was found in chironomid assemblages among lakes in different macrophyte classes. In a pair‐wise comparison, the poorly buffered mesotrophic lakes and the alkaline eutrophic lakes had significantly different chironomid assemblages. 5. Chironomid taxa commonly reported to be associated with macrophytes (Cricotopus, Endochironomus and Glyptotendipes) were shown also to be indicators of highly productive lakes lacking abundant submerged vegetation.

Refining the palaeoecology of lacustrine testate amoebae: insights from a plant macrofossil record from a eutrophic Scottish lake

“…5b) which suggests a strong secondary control on the assemblage that co-varies with eutrophication. In a palaeo-study of chironomid-macrophyte relationships from shallow, eutrophic Lake Søbygaard, Denmark (Brodersen et al 2001), changing macrophyte assemblage structure was identified as a key likely driver of chironomid community changes. Given the range of lake microhabitats occupied by testate amoebae (Lansac-Tôha et al 2014) and the synchronous response of both groups demonstrated here, it seems likely that similar relationships may also exist between testate amoebae and aquatic macrophytes.…”

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

“…Conversely, of the eight taxa of Orthocladiinae found as subfossils, only Nanocladius and three taxa in the genus Cricotopus were found as living larvae (Table 2). However, the number of living invertebrates found at each sampling station was high (49-1,173, with the exception of 23 specimens at 4.5 m water depth), and the number of identified chironomid head capsules (36-72) from subfossil Several genera that were encountered only in subfossil assemblages such as Corynoneura, Dicrotendipes, Endochironomus, and Metriocnemus are often associated with macrophytes (Pinder and Reiss 1983;Brodin 1986;Brodersen et al 2001;Merritt et al 2008;Moller Pillot 2009). Other groups, such as Bryozoa, are associated with woody substrates or aquatic macrophytes (Wood and Okamura 2005) and Xenochironomus xenolabis is known to be a parasite on Spongillidae (Pinder and Reiss 1983;Moog 2002).…”

Multi-proxy studies in palaeolimnology

“…Interest in plant macrofossils is greatly increasing, not only to provide terrestrial material for 14 C AMS dating, but also to help understand changes in aquatic biota in multi-proxy studies (e.g. Sayer et al 1999Sayer et al , 2006Birks et al 2001;Brodersen et al 2001;Odgaard and Rasmussen 2001;Bradshaw et al 2005b;Davidson et al 2005).…”