Amoebic gill disease (AGD) of cultured salmonids in Tasmania is caused by the amphizoic parasitic amoeba Neoparamoeba pemaquidensis. The freshwater tolerance of amoebae isolated from the gills of AGD-affected salmon (predominantly N. pemaquidensis) was tested in vitro using a trypan blue exclusion assay. Amoebae exposed to water containing high concentrations of Ca2+ or Mg2+ (200 mg l-1) showed high levels of survival up to 3 h of exposure. Exposure to water containing elevated Na+, choline chloride or water at different pH all had no significant survival of amoebae. Exposure of amoebae to different concentrations of chlorine dioxide, chloramine-T or hydrogen peroxide in artificially hard water demonstrated that chloramine-T and hydrogen peroxide were the most efficacious at killing amoebae in vitro. This work suggests that the hardness of freshwater may be an important factor for the survival of marine amoebae (predominantly N. pemaquidensis) on the gills of AGD-affected salmon and have significant implications with regard to the efficacy of freshwater bathing practices for the control of AGD on farms. Additionally, chloramine-T and hydrogen peroxide appear to be efficacious at killing marine gill amoebae in vitro and may be useful for the control of AGD in farmed Atlantic salmon. © 2003 Elsevier Science B.V. All rights reserved.

Item Type:	Refereed Article
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:	Fisheries - aquaculture not elsewhere classified
UTAS Author:	Powell, MD (Dr Mark Powell)
UTAS Author:	Clark, GA (Miss Gemma Clark)
ID Code:	26200
Year Published:	2003
Web of Science® Times Cited:	35
Deposited By:	TAFI - Aquaculture
Deposited On:	2003-08-01
Last Modified:	2011-09-20
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