Location: Harry K. Dupree Stuttgart National Aquaculture Research CntrTitle: Effect of water hardness/alkalinity and humic substances on the toxicity of peracetic acid to zebrafish embryos and pathogenic isolates
|LIU, DIBO - Leibniz Institute Of Freshwater Ecology And Inland Fisheries|
|PELLICER, ANNA - Humboldt University|
|BRÜGGMANN, ANNELIESE - Humboldt University|
|KIGGEN, MIRIJAM - Humboldt University|
|BEHRENS, SASCHA - Leibniz Institute Of Freshwater Ecology And Inland Fisheries|
|GOOD, CHRISTOPHER - Freshwater Institute|
|Straus, David - Dave|
|MEINELT, THOMAS - Leibniz Institute Of Freshwater Ecology And Inland Fisheries|
Submitted to: Aquaculture Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2021
Publication Date: 10/8/2021
Citation: Liu, D., Pellicer, A.M., Brüggmann, A., Kiggen, M., Behrens, S., Good, C., Straus, D.L., Meinelt, T. 2021. Effect of water hardness/alkalinity and humic substances on the toxicity of peracetic acid to zebrafish embryos and pathogenic isolates. Aquaculture Reports. 21:10090. https://doi.org/10.1016/j.aqrep.2021.100900.
Interpretive Summary: Peracetic acid (PAA) is a popular new disinfectant used in aquaculture. This study aims to help in the development of a treatment protocol to use PAA safely on fish. We looked at the effects of low, medium, and high hardness/alkalinity levels on the toxicity of PAA to zebrafish and its effectiveness to control problematic bacterial and fungal pathogens.
Technical Abstract: The prophylactic use of peracetic acid (PAA)-based disinfectants is becoming more popular in aquaculture due to rising concerns regarding sustainability, fish welfare and food safety. However, specific and effective PAA dosing protocols have not been developed to guide the aquaculture industry under diverse production conditions. In the present study, the effect of water hardness/alkalinity and humic substances (HS) on the toxicity of PAA to zebrafish Danio rerio embryos and the efficacy of PAA against the in vitro growth of Yersinia ruckeri and Saprolegnia parasitica was investigated. PAA concentrations that were safe to fish embryos demonstrated strong bactericidal, but limited fungistatic properties. In higher hardness/alkalinity water, or when HS was added, the same concentration of PAA resulted in a smaller pH decrease accompanied by a smaller increase of oxidation-reduction potential (ORP), and showed lower toxicity and weaker antimicrobial effects than in lower hardness/alkalinity waters. We suggest the determining factor of PAA toxicity and its antimicrobial capacity was likely ORP. At low hardness/alkalinity conditions, strong pH reduction (resulting in pH<5) was the dominant role in PAA toxicity to D. rerio embryos. In aquaculture settings, lower PAA doses should be used under lower hardness/alkalinity conditions. Addition of HS under lower hardness/alkalinity conditions can assist with reducing toxicity and the risk to fish. Finally, we determined that repeated PAA disinfection is necessary to achieve a sustained prophylaxis, and we caution that the instant formation of aggregates by HS at high hardness conditions and the subsequent attachment of bacteria may reduce their susceptibility to PAA disinfection.