Isotopic-based evidence for reduced benthic contributions to fish following a whole lake addition of nanosilver.

Abstract

Silver nanoparticles (AgNPs) are added as anti-bacterial and anti-odour ingredients to a wide range of textiles, with high potential for release into aquatic environments via domestic wastewater. Previous work demonstrating negative impacts of AgNP exposure on periphyton production suggests benthic primary production could be reduced in aquatic ecosystems impacted by AgNP discharge. To evaluate the potential for AgNPs to alter benthic-pelagic coupling in aquatic ecosystems, tissue stable isotope ratios of carbon and nitrogen from Northern Pike (Esox lucius) and Yellow Perch (Perca flavescens) were measured before, during, and after additions of AgNPs to a whole lake ecosystem, and compared to those collected from a nearby reference lake. A shift in carbon isotope ratios towards more negative values was observed in both P. flavescens and E. lucius collected from the lake where AgNPs were added, with no shift of similar magnitude observed in E. lucius from the reference lake. Consequently, Bayesian estimates of benthic energy consumed fell by 32% for P. flavescens and by 40% for E. lucius collected after AgNP additions relative to pre-addition estimates, greater in magnitude or opposite in direction of trends observed in our reference lake. Analyses suggest no changes in fish nitrogen isotope ratios related to AgNP additions. We hypothesize that the observed reduction in littoral energy use of fish reported here is a response to AgNP settling in littoral benthic habitats-the main habitat in lakes supporting periphyton-as AgNP has been shown elsewhere to significantly reduce rates of periphyton production. Further, our study highlights the need to broaden the scope of risk assessments for AgNPs and other emerging contaminants prone to settling to consider habitat-specific impacts on resource utilization by organisms following their release into aquatic ecosystems. This article is protected by copyright. All rights reserved.