title: Impacts of Silver Nanoparticles on a Natural Estuarine Plankton Community.
abstract: Potential effects of metal nanoparticles on aquatic organisms and food webs are hard to predict from the results of single-species tests under controlled laboratory conditions, and more realistic exposure experiments are rarely conducted. We tested whether silver nanoparticles (Ag NPs) had an impact on zooplankton grazing on their prey, specifically phytoplankton and bacterioplankton populations. If Ag NPs directly reduced the abundance of prey, thereby causing the overall rate of grazing by their predators to decrease, a cascading effect on a planktonic estuarine food web would be seen. Our results show that the growth rates of both phytoplankton and bacterioplankton populations were significantly reduced by Ag NPs at concentrations of ≥500 μg L(-1). At the same time, grazing rates on these populations tended to decline with exposure to Ag NPs. Therefore, Ag NPs did not cause a cascade of effects through the food web but impacted a specific trophic level. Photosynthetic efficiency of the phytoplankton was significantly reduced at Ag NPs concentrations of ≥500 μg L(-1). These effects did not occur at relatively low concentrations of Ag that are often toxic to single species of bacteria and other organisms, suggesting that the impacts of Ag NP exposure may not be apparent at environmentally relevant concentrations due to compensatory processes at the community level.
authors.affiliation: CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto , Porto, Portugal.
authors.forename: Mafalda S
authors.initials: MS
authors.lastname: Baptista
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Miller
authors.forename: Elisa R
authors.initials: ER
authors.lastname: Halewood
authors.forename: Shannon K
authors.initials: SK
authors.lastname: Hanna
authors.affiliation: CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto , Porto, Portugal.
authors.forename: C Marisa R
authors.initials: CM
authors.lastname: Almeida
authors.affiliation: CIIMAR/CIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto , Porto, Portugal.|Departamento de Biologia, Faculdade de Ciências, Universidade do Porto , Porto, Portugal.
authors.forename: Vitor M
authors.initials: VM
authors.lastname: Vasconcelos
authors.forename: Arturo A
authors.initials: AA
authors.lastname: Keller
authors.forename: Hunter S
authors.initials: HS
authors.lastname: Lenihan
mesh_terms: D000818:Animals; D017753:Ecosystem; D063366:Estuaries; D005453:Fluorescence; D052836:Heterotrophic Processes / Q000187:drug effects; D053768:Metal Nanoparticles / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D052817:Phototrophic Processes / Q000187:drug effects; D010839:Phytoplankton / Q000187:drug effects; D010860:Pigments, Biological / Q000378:metabolism; D010933:Plankton / Q000187:drug effects*; D012834:Silver / Q000633:toxicity*; D015048:Zooplankton / Q000187:drug effects
chemical_list: D010860:Pigments, Biological; D012834:Silver