Intraregional variability in chironomid-inferred temperature estimates and the influence of river inundations on lacustrine chironomid assemblages |
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| Authors: | S Engels S J P Bohncke O Heiri M Nyman |
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| Institution: | (1) Department of Paleoclimatology and Geomorphology, Faculty of Earth and Life Sciences, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands;(2) Palaeoecology, Laboratory of Palaeobotany and Palynology, Institute of Environmental Biology, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands;(3) Department of Biological and Environmental Sciences, Aquatic Sciences, University of Helsinki, P. O. Box 65, Viikinkaari, 00014, Finland |
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| Abstract: | Floodplain lakes are rarely analysed for fossil chironomids and usually not incorporated in modern chironomid-climate calibration
datasets because of the potential complex hydrological processes that could result from flooding of the lakes. In order to
investigate this potential influence of river inundations on fossil chironomid assemblages, 13 regularly inundated lakes and
20 lakes isolated from riverine influence were sampled and their surface sediments analysed for subfossil chironomid assemblages.
The physical and chemical settings of all lakes were similar, although the variation in the environmental variables was higher
in the lakes isolated from riverine influence. Chironomid concentration and taxon richness show significant differences between
the two classes of lakes, and the variation in these variables is best explained by loss-on-ignition of the sediments (LOI).
Relative chironomid abundances show some differences between the two groups of lakes, with several chironomid taxa occurring
preferentially in one of the two lake-types. The variability in chironomid assemblages is also best explained by LOI. Application
of a chironomid-temperature inference model shows that both types of lakes reconstruct July air temperatures that are equal
to, or slightly underestimating, the measured temperature of the region. We conclude that, although there are some differences
between the chironomid assemblages of floodplain lakes and of isolated lakes, these differences do not have a major effect
on chironomid-based temperature reconstruction. |
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| Keywords: | Chironomids River inundation Floodplain Temperature inference Finland |
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