Honors College

Document Type

Honors Thesis

Publication Date

Spring 5-2017


Atlantic salmon is a common aquaculture species that is now greatly impacted by sea lice and amoebic gill disease. Currently, one of the treatments uses hydrogen peroxide (H2O2) because it breaks down safely in water, leaving no toxic residues like some of the previous treatments. Hydrogen peroxide was an effective treatment previously, but now resistance seems to be developing amongst the disease organisms and, if too high a dose is used, it can harm the salmon. Antioxidants, specifically superoxide dismutase (SOD), catalase (CAT), and both independent and dependent glutathione peroxidase (GPx), are present in organisms to break down reactive oxygen species (ROS) like H2O2. The goal of this study was to determine if antioxidants follow a daily rhythm, so that an ideal treatment time and a higher dose of H2O2 can be used to kill harmful organisms without causing damage to the salmon, since there are clear indications that many physiological processes vary on a circadian rhythm. Three fish were sampled every four hours for fifty-two hours to determine if the levels of SOD, CAT, and GPx varied over time. Although this data showed some evidence of a daily rhythm, no statistical significance was found except in the GPx dependent levels. This experiment should be repeated using more than one tank and measuring cortisol levels to determine if stress was a possible contributing factor to the lack of statistical significance, or if human error caused the large amount of variance observed.