Acute Adverse Effects of Metallic Nanomaterials on Cardiac and Behavioral Changes in Daphnia Magna

Abstract

Nanomaterials are widely believed to induce toxic effects on organisms by evoking oxidative stress. In this study, we evaluated the toxic effects of nanomaterials on cardiac and behavioral changes in Daphnia magna under varying exposure conditions. Titanium dioxide nanoparticles (TiO2 NPs), silver nanoparticles (AgNPs), and silver nitrate (AgNO3) were selected for the acute toxicity tests. The adverse effects of the substances on the neonates including heart rate, swimming speed, and oxidative stress, were measured. The heart rate level decreased as the concentration of NPs and silver ions (Ag+) increased. The average swimming speed was measured to be approximately 15 mm/min for the control group. The swimming speed generally increased for longer exposure to both NPs, although it reached a plateau at the lowest concentration of AgNPs. A similar but less clear trend was observed for Ag+. For all substances, the overall swimming speed exhibited no correlation or weak negative correlations with the exposure concentration. The oxidative stress levels increased after exposure compared to the control group. We conclude that aquatic nanotoxicity tests should consider multilevel physicochemical, physiological, and behavioral parameters for the official guidelines to quantify more robust adverse outcomes.

Real-time assessment of the impacts of polystyrene and silver nanoparticles on hatching process and early-stage development ofArtemiausing a microfluidic platform

“…With greater acute toxicity (Figure 8A), Ag NP was observed to deliver more stimulation as an overcompensation for a homeostasis imbalance 140 and encouraged faster swimming speed as an escape response from a dangerous environment 139 , or caused hyperactivity as observed in two other aquatic invertebrate larvae. A similar increase in swimming speed was observed when Daphnia magna was exposed to Ag NP 141 . Related to this the duration of the hatching stage within the 24-hour experimental timeframe decreased significantly in the presence of Ag NPs vs PS NPs (Figure 4) such that the hatched nauplii were exposed to PS NPs for a longer period.…”