Assessing the efficacy of chironomid and diatom assemblages in tracking eutrophication in High Arctic sewage ponds
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PRIMARY RESEARCH PAPER
Assessing the efficacy of chironomid and diatom assemblages in tracking eutrophication in High Arctic sewage ponds E. M. Stewart • R. McIver • N. Michelutti M. S. V. Douglas • J. P. Smol
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Received: 24 January 2013 / Revised: 22 July 2013 / Accepted: 15 August 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract Eutrophication is the most common water quality issue affecting freshwaters worldwide. Paleolimnological approaches have been used in temperate regions to track eutrophication over time, placing changes in historical context. Diatoms (Bacillariophyta) have a direct physiological response to changes in nutrients and are effective indicators of lake trophic status. Chironomids (Diptera) have also been used to track nutrient conditions; however, given that nutrients and oxygen are often tightly linked, it is difficult to disentangle which variable is driving shifts in assemblages. Here, we analyze chironomid and
diatom remains in sediments from sewage-impacted ponds in the High Arctic. These ponds have the unusual characteristics of elevated nutrient and oxygen concentrations, unlike those of typical eutrophic lakes where deepwater oxygen is often depleted. Our data show that while diatom assemblages responded to changing nutrients, no concomitant changes in chironomid assemblage composition were recorded. Furthermore, the dominance of oligotrophic, cold stenothermic chironomid taxa, and lack of so-called ‘‘eutrophic’’ species in the eutrophic sewage ponds suggests that oxygen, not nutrients, structures chironomid assemblages at these sites.
Handling editor: Jasmine Saros
Keywords Paleolimnology Chironomids Diatoms Eutrophication High Arctic
Electronic supplementary material The online version of this article (doi:10.1007/s10750-013-1667-6) contains supplementary material, which is available to authorized users.
Introduction E. M. Stewart (&) R. McIver N. Michelutti J. P. Smol Paleoecological Environmental Assessment and Research Laboratory, Department of Biology, Queen’s University, Kingston, ON K7L 3N6, Canada e-mail: [email protected] Present Address: R. McIver Life Science Centre, Department of Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada M. S. V. Douglas Canadian Circumpolar Institute, University of Alberta, Edmonton, AB T6G 2E3, Canada
Sedimentary chironomid (Diptera) remains are often used in paleolimnological investigations of eutrophication because they respond to numerous productionrelated variables. As a result, chironomid-based inference models have been developed to infer concentrations of chlorophyll a (chl-a) (Brodersen & Lindegaard, 1999), total phosphorous (TP) (Brooks et al., 2001), and hypolimnetic oxygen (Quinlan et al., 1998). However, in temperate dimictic lakes, nutrients and deepwater oxygen concentrations are often tightly linked (because of interactions between primary
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Hydrobiologia
production and decomposition) and so, in most deep eutrophic lakes hypolimnetic oxygen is low. Monitoring and experimental evide
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