Freshwater Crayfish: A Potential Benthic-Zone Indicator of Nanosilver and Ionic Silver Pollution

Nowadays, silver nanoparticles (AgNPs) are utilized in numerous applications, raising justified concerns about their release into the environment. This study demonstrates the potential to use freshwater crayfish as a benthic-zone indicator of nanosilver and ionic silver pollution. Crayfish were acclimated to 20 L aquaria filled with Hudson River water (HRW) and exposed for 14 days to widely used Creighton AgNPs and Ag(+) at doses of up to 360 μg L(-1) to surpass regulated water concentrations. The uptake and distribution of Ag in over 650 exoskeletons, gills, hepatopancreas and muscles samples were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES) in conjunction with two complementary U.S. EPA-endorsed methods: the external calibration and the standard additions. Reflecting the environmental plasticity of the two investigated species, Orconectes virilis accumulated in a dose-dependent manner more Ag than Procambarus clarkii (on average 31% more Ag). Both species showed DNA damage and severe histological changes in the presence of Ag. However, Ag(+) generally led to higher Ag accumulations (28%) and was more toxic. By the harvest day, about 14 ± 9% of the 360 μg L(-1) of AgNP exposure in the HRW oxidized to Ag(+) and may have contributed to the observed toxicities and bioaccumulations. The hepatopancreas (1.5-17.4 μg of Ag g(-1) of tissue) was identified as the best tissue-indicator of AgNP pollution, while the gills (4.5-22.0 μg g(-1)) and hepatopancreas (2.5-16.7 μg g(-1)) complementarily monitored the presence of Ag(+).