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Repeated sublethal freshwater exposures reduce the amoebic gill disease parasite, Neoparamoeba perurans, on Atlantic salmon


Wright, DW and Nowak, B and Oppedal, F and Crosbie, P and Stien, LH and Dempster, T, Repeated sublethal freshwater exposures reduce the amoebic gill disease parasite, Neoparamoeba perurans, on Atlantic salmon, Journal of Fish Diseases, 41, (9) pp. 1403-1410. ISSN 0140-7775 (2018) [Refereed Article]

Copyright Statement

Copyright 2018 John Wiley & Sons Ltd.

DOI: doi:10.1111/jfd.12834


Freshwater bathing is one of the main treatment options available against amoebic gill disease (AGD) affecting multiple fish hosts in mariculture systems. Prevailing freshwater treatments are designed to be long enough to kill Neoparamoeba perurans, the ectoparasite causing AGD, which may select for freshwater tolerance. Here, we tested whether using shorter, sublethal freshwater treatment durations are a viable alternative to lethal ones for N.áperurans (2ľ4áhr). Under inávitro conditions, gill‐isolated N.áperurans attached to plastic substrate in sea water lifted off after ≥2ámin in freshwater, but survival was not impacted until 60ámin. In an inávivo experiment, AGD‐affected Atlantic salmon Salmo salar subjected daily to 30ámin (sublethal to N.áperurans) and 120ámin (lethal to N.áperurans) freshwater treatments for 6ádays consistently reduced N.áperurans cell numbers on gills (based on qPCR analysis) compared to daily 3ámin freshwater or seawater treatments for 6ádays. Our results suggest that targeting cell detachment rather than cell death with repeated freshwater treatments of shorter duration than typical baths could be used in AGD management. However, the consequences of modifying the intensity of freshwater treatment regimes on freshwater tolerance evolution in N.áperurans populations require careful consideration.

Item Details

Item Type:Refereed Article
Keywords:freshwater, mariculture, moderate vs aggressive treatment, Neoparamoeba perurans, parasite control
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:Nowak, B (Professor Barbara Nowak)
UTAS Author:Crosbie, P (Dr Philip Crosbie)
ID Code:129951
Year Published:2018
Web of Science® Times Cited:7
Deposited By:Fisheries and Aquaculture
Deposited On:2019-01-02
Last Modified:2019-04-26

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