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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Current and Future Approaches for Using Benthic Algae to Monitor and Assess Aquatic Ecosystems I
DIATOM MORPHOLOGY AS A TOOL TO MONITOR METAL POLLUTION.
A. Cattaneo1, S. Wunsam2, and Y. Couillard3. 1Département de sciences biologiques, Université de Montréal, Montréal, Québec, Canada H3C 3J7, 211437 76th Avenue, Edmonton, Alberta, Canada T6G 0K5, 3Chemical Evaluation Division, Existing Substances Branch, Environment Canada, Hull, Québec, Canada K1A 0H3
We observed frequent morphological alterations in diatom remains from sedimentary cores collected in Lago d’Orta (Italy) and Lac Dufault (Québec). Although located in different continents and with strongly different morphology and geology, these lakes share a long history of metal pollution. In both cases, this pollution originated around 1930 but resulting from different industrial activities: implantation of textile and electroplating factories in Lago d’Orta and intense mining in Lac Dufault. The onset of metal contamination, in particular of high copper concentrations, was accompanied by the appearance of strikingly similar morphological changes in the diatoms of the two lakes. Frequency of frustules with distortions in the valvar plane was higher in impacted sediment layers than in deeper pre-contamination sections of the cores. In several diatom taxa, we observed a significant decrease in frustule length along the cores, which was correlated to an increase in metal concentration. A literature survey shows that such morphological changes are not peculiar to these lakes but are a widespread response to metal stress. Therefore, deformities and size reduction could offer an easy and powerful tool to follow perturbation and recovery from metal pollution and possibly other contaminations.
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