Response of littoral chironomid communities and organic matter to late glacial lake—level,vegetation and climate changes at Lago dell’Accesa (Tuscany,Italy) |
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| Authors: | Laurent Millet Boris Vannière Valérie Verneaux Michel Magny Jean Robert Disnar Fatima Laggoun-Défarge Anne Véronique Walter-Simonnet Gilles Bossuet Elena Ortu Jacques-Louis de Beaulieu |
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| Institution: | 1.Laboratoire de Chrono-Ecologie, UMR 6565 CNRS, UFR Sciences et Techniques,Université de Franche-Comté,Besan?on cedex,France;2.Laboratoire EDYTEM, UMR 5204, CISM,Université de Savoie, Le Bourget du Lac cedex,France;3.Laboratoire de Biologie Environnementale, EA 3184 USC INRA, UFR Sciences et Techniques, Université de Franche-Comté,Besan?on cedex,France;4.Institut des Sciences de la Terre d’Orléans, UMR 6113 CNRS,Université d’Orléans,Orléans Cedex 2,France;5.Laboratoire de Géosciences, UFR Sciences et Techniques,Université de Franche-Comté,Besan?on cedex,France;6.Laboratoire IMEP, UMR 6116, Europ?le Méditerranéen de l’Arbois,Aix-en-Provence cedex 4,France |
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| Abstract: | This study focuses on the response of lacustrine littoral chironomid communities to late glacial changes in limnological,
environmental and climate conditions in the Mediterranean context. Late glacial chironomid (Diptera: Chironomidae) assemblages,
organic petrography and geochemistry were analysed in a sediment core from the littoral zone of Lago dell’Accesa (Tuscany,
Italy), where the lake-level fluctuations and the vegetation history have been previously reconstructed. Comparison of the
chironomid stratigraphy to other proxies (pollen assemblages, organic petrography and geochemistry, lake-level) and regional
climate reconstruction suggested the predominant influence of lake-level changes on the littoral chironomid fauna. The main
lowering events that occurred during the Oldest and the Younger Dryas were followed by higher proportions of taxa typical
of littoral habitats. A complementary study of organic matter suggested the indirect impact of lake-level on the chironomids
through changes in humic status and habitat characteristics, such as the type of substrate and aquatic macrophyte development.
Several chironomid taxa, such as Glyptotendipes, Microtendipes and Cricotopus type patens, were identified as possible indicators of low lake-level in the late glacial records. Nevertheless, this study suggested
that parallel analyses of organic matter and chironomid assemblages may be needed to circumvent misinterpretation of littoral
chironomid assemblage stratigraphy. There was a weak response of the chironomid assemblages to small lake-level lowerings
that corresponded to the Older Dryas and Preboreal oscillations. A higher level of determination, e.g. to the species group
level, may be necessary to increase the sensibility of the indicators to lake-level changes. |
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| Keywords: | Chironomids Organic matter Late glacial Paleolimnology Lake-level Italy |
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