Acute Toxicological Response of Daphnia and Moina to Hydrogen Peroxide

Hydrogen peroxide (H2O2) is suggested to be an environmentally benign chemical that may be used for wastewater purification. A recent study on the application of H2O2 in a wastewater stabilization pond (WSP) showed that H2O2 is a promising method to decrease high amounts of potentially toxic cyanobacteria. However, WSPs are complex biological systems that require healthy bacterial, phytoplankton, and zooplankton communities for optimal performance. Therefore, if H2O2 is to be regularly used in WSPs, its effect on all components of a healthy WSP food web, including zooplankton, must be assessed. This study quantifies the acute toxicity of H2O2 to Moina and Daphnia, two zooplankton genera that are common in WSPs in Western Australia’s Mediterranean climate. The results indicate that Daphnia carinata is less susceptible to H2O2 than Moina sp., as mean survival time was significantly higher at concentrations ≥2  mg H2O2/L. Additionally, the LC50 was 5.6  mg  H2O2/L in Daphnia and 2  mg H2O2/L in Moina, whereas the no observed adverse effect concentration (NOAEC) was 3 and 1.5  mg H2O2/L for Daphnia and Moina, respectively. These values are below H2O2 doses that effectively removed toxic cyanobacteria from WSPs, and therefore indicate the urgent need to critically assess the effect of H2O2 on biological communities during field trials to ensure continuous performance of WSPs.