A Multi-Life Stage Comparison of Silver Nanoparticle Toxicity on the Early Development of Three Canadian Fish Species.

Information on the effects of silver nanoparticles (AgNPs) in fish has mostly been generated from standard laboratory species and short-term toxicity tests. However, there is significant uncertainty regarding AgNP toxicity to native species of concern in North America, particularly in northern freshwater ecosystems. We assessed the chronic toxicity of AgNPs in early life stages of three North American fish species: rainbow trout (Oncorhynchus mykiss), lake trout (Salvelinus namaycush), and northern pike (Esox lucius). Newly fertilized embryos were exposed to nominal aqueous concentrations of 0.1, 0.3, 1.0, 3.0, 10.0, or 30.0 nM AgNPs for 126 (rainbow trout), 210 (lake trout), and 25 (northern pike) days. Endpoints included cumulative developmental time (°C × day or degree-days to 50% life-stage transition), mortality, fork length, embryonic malformations, cumulative survival, and histopathology of gill and liver in larvae/alevins. The results showed life stage-specific differences in responses, with endpoints during the embryonic stage occurring more often and at lower concentrations compared to larval/alevin and juvenile stages. Sensitivities among species were highly dependent on the endpoints measured, although developmental time appeared to be the most consistent endpoint across species. At embryonic and larval/alevin stages, northern pike was the most sensitive species (lowest observable effect concentration of 0.1 nM using developmental time). Rainbow trout displayed similar responses to lake trout across multiple endpoints and therefore seems to be an adequate surrogate for trout species in ecotoxicology studies. Moreover, while mortality during individual life stages was not generally affected, the cumulative mortality across life stages was significantly affected, which highlights the importance of chronic, multi-life-stage studies. Environ Toxicol Chem 2021;40:3337-3350. © 2021 SETAC.