The Acute and Delayed Mortality of the Northern Krill (Meganyctiphanes norvegica) When Exposed to Hydrogen Peroxide

Bath treatment pharmaceuticals used to control sea lice infestations in the salmonid industry, such as hydrogen peroxide (H2O2), are released directly into the environment where non-target organisms are at risk of exposure. The aim of this study was to determine the threshold concentrations for mortality of the Northern krill,Meganyctiphanes norvegica,a major component of the north Atlantic marine ecosystem. To assess the lethal effects of H2O2, we carried out a series of 1 h acute toxicity tests and assessed mortality through a 48 h post-exposure period. One-hour exposure to 170 mg/L, corresponding to 10% of the recommended H(2)O(2)treatment, caused 100% mortality and a subsequent acute median-lethal concentration LC50 value of 32.5 mg/L. Increased mortality was observed with time in all exposed groups, resulting in successively lower LC(50)values during the post-exposure period. The suggested H(2)O(2)concentrations have the potential of causing negative effects to the Northern krill.