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Cyclic hypoxia exposure accelerates the progression of amoebic gill disease

Citation

Oldham, T and Dempster, T and Crosbie, P and Adams, M and Nowak, B, Cyclic hypoxia exposure accelerates the progression of amoebic gill disease, Pathogens, 9, (8) Article 597. ISSN 2076-0817 (2020) [Refereed Article]


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Copyright Statement

Copyright 2020 by the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.3390/pathogens9080597

Abstract

Amoebic gill disease (AGD), caused by the amoeba Neoparamoeba perurans, has led to considerable economic losses in every major Atlantic salmon producing country, and is increasing in frequency. The most serious infections occur during summer and autumn, when temperatures are high and poor dissolved oxygen (DO) conditions are most common. Here, we tested if exposure to cyclic hypoxia at DO saturations of 4060% altered the course of infection with N. perurans compared to normoxic controls maintained at ≥90% DO saturation. Although hypoxia exposure did not increase initial susceptibility to N. perurans, it accelerated progression of the disease. By 7 days post-inoculation, amoeba counts estimated from qPCR analysis were 1.7 times higher in the hypoxic treatment than in normoxic controls, and cumulative mortalities were twice as high (16 4% and 8 2%), respectively. At 10 days post-inoculation, however, there were no differences between amoeba counts in the hypoxic and normoxic treatments, nor in the percentage of filaments with AGD lesions (control = 74 2.8%, hypoxic = 69 3.3%), or number of lamellae per lesion (control = 30 0.9%, hypoxic = 27.9 0.9%) as determined by histological examination. Cumulative mortalities at the termination of the experiment were similarly high in both treatments (hypoxic = 60 2%, normoxic = 53 11%). These results reveal that exposure to cyclic hypoxia in a diel pattern, equivalent to what salmon are exposed to in marine aquaculture cages, accelerated the progression of AGD in post-smolts.

Item Details

Item Type:Refereed Article
Keywords:Salmo salar, Atlantic salmon, aquaculture, dissolved oxygen, Paramoeba/Neoparamoeba perurans, stress
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Fisheries sciences
Research Field:Fish pests and diseases
Objective Division:Animal Production and Animal Primary Products
Objective Group:Fisheries - aquaculture
Objective Field:Aquaculture fin fish (excl. tuna)
UTAS Author:Oldham, T (Mrs Tina Oldham)
UTAS Author:Crosbie, P (Dr Philip Crosbie)
UTAS Author:Adams, M (Dr Mark Adams)
UTAS Author:Nowak, B (Professor Barbara Nowak)
ID Code:140305
Year Published:2020
Web of Science® Times Cited:6
Deposited By:Fisheries and Aquaculture
Deposited On:2020-08-06
Last Modified:2021-02-10
Downloads:4 View Download Statistics

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