Influence of Ultrafine Bubbles (UFBs) on Cadmium Toxicity in Polypedilum nubifer (Chironomidae).

Cadmium is one of the major pollutants that threatens aquatic ecosystems. Aquatic organisms such as aquatic insects are commonly used as bioindicators to assess the impact of pollutants in the environment. Recent studies have demonstrated that ultrafine bubbles (UFBs), gas-filled nanobubbles with unique properties, can modulate metal toxicity in aquatic organisms. However, their role in toxicity assessments involving aquatic insects remains limited. In this study, the effects of UFBs on Cd-induced toxicity in Polypedilum nubifer were investigated. Cadmium exposure led to inhibited larval growth, reduced adult emergence, increased activity of biochemical markers, and greater Cd accumulation in larval tissues. When co-treated with UFBs, survival, larval growth and adult emergence did not differ significantly compared to the Cd treatment alone. However, UFB treatment did lead to a significant reduction in internal Cd accumulation. Furthermore, the activities of catalase (CAT) and glutathione S-transferase (GST), which increased under Cd exposure, were reduced to levels that aligned closely with the control group. In conclusion, this study provides the potential application of UFB for mitigating heavy metal pollution at a physiological level, specifically by lowering heavy metal accumulation and modulating oxidative stress-related defense responses.