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Assessing the effects of climate and volcanism on diatom and chironomid assemblages in an Andean lake near Quito, Ecuador

Neal Michelutti, Jillian L. Lemmen, Colin A. Cooke, William O. Hobbs, Alexander P. Wolfe, Joshua Kurek, John P. Smol
  • Jillian L. Lemmen
    Queen’s University, Canada
  • Colin A. Cooke
    Government of Alberta, Canada
  • William O. Hobbs
    Washington State Department of Ecology, United States
  • Alexander P. Wolfe
    University of Alberta, Canada
  • Joshua Kurek
    Queen’s University, Canada
  • John P. Smol
    Queen’s University, Canada

Abstract

The tropical Andes are undergoing climate changes that rival those occurring anywhere else on the planet, and are likely to have profound consequences for ecosystems. Paleolimnological investigations of remote mountain lakes can provide details of past environmental change, especially where monitoring data are absent. Here, we reconstruct fossil diatom and chironomid communities spanning the last several hundred years from an Andean lake located in an ecological reserve near Quito, Ecuador. Both diatoms and chironomids recorded assemblage shifts reflective of changing climate conditions. The diatoms are likely responding primarily to temperature-related limnological changes, recording an increase in the number of planktonic taxa in the most recent sediments. This change is consistent with warmer conditions that result in enhanced periods of thermal stratification, allowing planktonic species to proliferate. The chironomids appear to respond mainly to a change in precipitation regime, recording a greater number of terrestrial and semi-terrestrial taxa that have been transported to the lake. A thick tephra deposit at the base of the sediment core affected both diatom and chironomid assemblages. The diatoms registered a change in species composition highlighting the ability of certain taxa to rapidly colonize new environments. In contrast, the chironomids showed a marked drop in abundance immediately following the tephra, but no change in species composition. In both cases the ecological response was short-lived, illustrating the resiliency of the lake to return to baseline conditions following volcanic inputs.

Keywords

Tropical Andes; Ecuador; paleolimnology; diatoms; Chironomids; climate change; Tephra; mercury.

Supporting Agencies

Natural Sciences and Engineering Research Council of Canada (NSERC); National Geographic Society (NGS)

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Submitted: 2015-08-25 18:18:06
Published: 2015-12-30 00:00:00
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Copyright (c) 2015 Neal Michelutti, Jillian L. Lemmen, Colin A. Cooke, William O. Hobbs, Alexander P. Wolfe, Joshua Kurek, John P. Smol

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