Phosphorus availability modulates the toxic effect of silver on aquatic fungi and leaf litter decomposition
•Ag significantly affected decomposition rates, fungal biomass and community structure, leaf litter elemental composition, and Gammarus fossarum feeding rate, but only at very high [Ag].•At low [Ag], P was the main driver of decomposition, fungal biomass, and G. fossarum feeding rate.•Interactive ef...
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| Published in: | Aquatic toxicology 2013-11, Vol.144-145, p.199-207 |
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| Main Authors: | , , , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | •Ag significantly affected decomposition rates, fungal biomass and community structure, leaf litter elemental composition, and Gammarus fossarum feeding rate, but only at very high [Ag].•At low [Ag], P was the main driver of decomposition, fungal biomass, and G. fossarum feeding rate.•Interactive effects between Ag and P were reported for fungal biomass and community structure, as well as G. fossarum feeding rate.•Increased G. fossarum feeding rate under low P could lead to increased ingestion of contaminated resources in oligotrophic contaminated ecosystems.
The functioning of forested headwater streams is intimately linked to the decomposition of leaf litter by decomposers, mainly aquatic hyphomycetes, which enables the transfer of allochthonous carbon to higher trophic levels. Evaluation of this process is being increasingly used as an indicator of ecosystem health and ecological integrity. Yet, even though the individual impacts of contaminants and nutrient availability on decomposition have been well studied, the understanding of their combined effects remains limited. In the current study, we investigated whether the toxic effects of a reemerging contaminant, silver (Ag), on leaf litter decomposition could be partly overcome in situations where microorganisms were benefitting from high phosphorus (P) availability, the latter being a key chemical element that often limits detritus decomposition. We also investigated whether these interactive effects were mediated by changes in the structure of the aquatic hyphomycete community. To verify these hypotheses, leaf litter decomposition by a consortium of ten aquatic hyphomycete species was followed in a microcosm experiment combining five Ag contamination levels and three P concentrations. Indirect effects of Ag and P on the consumption of leaf litter by the detritivorous crustacean, Gammarus fossarum, were also evaluated. Ag significantly reduced decomposition but only at the highest concentration tested, independently of P level. By contrast, P and Ag interactively affected fungal biomass. Both P level and Ag concentrations shaped microbial communities without significantly affecting the overall species richness. Finally, the levels of P and Ag interacted significantly on G. fossarum feeding rates, high [Ag] reducing litter consumption and low P availability tending to intensify the feeding rate. Given the high level of contaminant needed to impair the decomposition process, it is unlikely that a direct |
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| ISSN: | 0166-445X 1879-1514 |