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Why bother to identify Chironomus species used for contaminant monitoring.

Proulx, Isabelle; Hare, Landis (2011). Why bother to identify Chironomus species used for contaminant monitoring. In: 18th International Symposium on Chironomidae, 4-6 juillet 2011, Trondheim, Norvège.

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Résumé

Chironomid larvae have great potential as contaminant biomonitors because they are present in a wide variety of freshwaters, including those that are highly contaminated. Since chironomid species are notoriously difficult to identify, closely related species are often pooled for contaminant analysis. However, in doing so, one presumes that contaminant concentrations do not differ markedly among the pooled species. We tested this assumption on the widespread midge Chironomus by collecting larvae of this genus from lakes located along a metal-contamination gradient and then identifying species using a combination of molecular and morphological techniques. By measuring trace metal concentrations in each Chironomus species we discovered that, within a given lake, the concentrations of some metals (Cd and Se) differed among sympatric species. Among lakes, metal concentrations in the various Chironomus species differed in a consistent manner such that certain species had consistently higher concentrations of some metals than did others. To determine why species sharing the same habitat differ in their metal concentrations, we measured larval sulfur isotopic ratios. These measurements revealed that Chironomus species sharing the same habitat tend to feed at different depths in sediment where metal concentration and/or bioavailability are likely to differ. Overall, our results suggest that a “one-size fits all” approach for Chironomus species may not be valid and that behavioral differences among these morphologically-similar larvae influence their exposure to contaminants.

Type de document: (Article)
Informations complémentaires: Affiche
Mots-clés libres: biogeochemistry; Chironomid; biomonitoring
Centre: Centre Eau Terre Environnement
Date de dépôt: 13 déc. 2016 21:25
Dernière modification: 13 déc. 2016 21:25
URI: http://espace.inrs.ca/id/eprint/4773

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