Changes in yellow perch diets associated with nanosilver exposure in freshwater lakes

Abstract

Freshwater lake experiments on the effects of nanosilver were completed at the Experimental Lakes Area in northwestern Ontario. Since nanosilver has antibacterial properties it is expected to have negative effects on microorganisms causing indirect consequences to an aquatic food web. Diets of Yellow Perch (Perca flavescens) populations from a lake with nanosilver added were compared to an unmanipulated reference lake. These two study lakes were compared across the same duration period of nanosilver addition years (2014 & 2015) to lake recovery (2016 to present) during summer and fall seasons. Nanosilver was added to the lakes with a mean particle size of 40 nm with 9 kg added in 2014 and 6 kg added in 2015. The results showed no differences in diet contents due to exposure to nanosilver. There was a greater propensity for piscivory in large Yellow Perch from Lake 239, whereas Lake 222 had high levels of benthivory in both time periods and seasons but no evidence of piscivory. This study showed only natural alterations in diets, but no effects from the nanosilver added at a nearshore point source. In conclusion, ongoing monitoring is recommended, to see if future tests reveal any effects from nanosilver material entry to freshwater aquatic ecosystems.