Potential risks of silver nanoparticles on aquatic food webs and ecosystem processes are expected in systems which depend on the well-being of microorganisms.
Background
Metallic silver in the form of nanometer-size particles (AgNP) is one of the most used nanomaterials currently applied in commercial products and medical appliances. Its widespread use is based on the fact that silver is toxic to a variety of bacteria, but has a low toxicity to humans. The antimicrobial properties of AgNP, however, pose potential environmental risks. As AgNP are intentionally applied as bactericide, the greatest environmental risks are expected to be in systems dominated by microorganisms.
Aim
Therefore, with the objective of assessing the effects of AgNP on food-web interactions and key ecosystem processes in aquatic environments, we have selected two systems that depend on healthy microorganismal communities. The first community consists of microbial decomposers that degrade plant litter. In streams, this litter-decomposition system is dominated by aquatic fungi, which strongly interact with litter-colonising bacteria and litter-consuming invertebrates. A second important system, tied to another vital ecosystem process in streams (i.e. primary production), are autotrophic biofilms, dominated by algae and various other microorganisms that grow on submerged surfaces. In the biofilm, algae interact with bacteria, and herbivores graze the biofilm. Both systems produce substantial amounts of biomass that is subsequently channeled to higher trophic levels in the food web. Thus, examination of the effects of AgNP on the various components of these systems and their performance will provide information on the consequences of AgNP to food-web configuration, litter decomposition, primary productivity and overall energy flow in stream ecosystems.
Significance
The results of this study will contribute to laying a solid foundation that enables environmental risk assessment at the food-web and ecosystem level. Moreover, information on potential adverse environmental effects of AgNP will be instrumental to developing well-founded regulations and, thus, facilitating responsible use of AgNP.
Original title: Silver nanoparticle effects on simple stream food webs and ecosystem processes
Grant: CHF 437'698.-
Duration: 36 months
Project leader
- Dr. Renata Behra