Free-living Neoparamoeba perurans depth distribution is mostly uniform in salmon cages, but reshaped by stratification and potentially extreme fish crowding

Wright, Daniel; Nowak, Barbara F.; Oppedal, Frode; Bridle, Andrew R.; Dempster, Tim

doi:10.3354/aei00233

Cited by 13 publications

(14 citation statements)

References 43 publications

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“…Due to inhibition detected during a preliminary dilution series test, qPCR was performed on 1:20 diluted total nucleic acid extract. Amoebae numbers were estimated based on a copy number of 2,880 per 1 N. perurans cell (Wright, Nowak, Oppedal, Bridle, & Dempster, ; Wright et al., ).…”

Section: Methodsmentioning

confidence: 99%

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

Wright

Nowak

Oppedal

et al. 2018

Journal of Fish Diseases

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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. perurans (2-4 hr). Under in vitro conditions, gill-isolated N. perurans attached to plastic substrate in sea water lifted off after ≥2 min in freshwater, but survival was not impacted until 60 min. In an in vivo experiment, AGD-affected Atlantic salmon Salmo salar subjected daily to 30 min (sublethal to N. perurans) and 120 min (lethal to N. perurans) freshwater treatments for 6 days consistently reduced N. perurans cell numbers on gills (based on qPCR analysis) compared to daily 3 min freshwater or seawater treatments for 6 days. 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. perurans populations require careful consideration.

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Section: Methodsmentioning

confidence: 99%

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

Wright

Nowak

Oppedal

et al. 2018

Journal of Fish Diseases

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“…Environmental risk factors for AGD are high salinity (Clark & Nowak, 1999), proximity to an infected site and elevated temperatures (Douglas‐Helders et al 2001). Described husbandry risk factors include high stocking density (Crosbie et al 2010) and local crowding, which can be five times the stocking density at times and might be reduced by the use of lights (Wright et al 2015, 2017). Biofouling, which are the diverse assemblage of flora and fauna formed by successive growth of organisms on solid surfaces exposed to the marine environment (Tan et al 2002) may be a risk factor for AGD, (Tan et al 2002).…”

Section: Specific Types Of Marine Salmonid Gill Diseasementioning

confidence: 99%

Epidemiology of marine gill diseases in Atlantic salmon (Salmo salar) aquaculture: a review

Boerlage

Ashby²,

Herrero³

et al. 2020

Reviews in Aquaculture

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Gill disease of farmed Atlantic salmon (Salmo salar) in the marine environment has emerged as a significant problem for the salmon aquaculture industry. Different types of marine salmon gill disease reported include amoebic gill disease (AGD), parasitic gill disease, viral gill disease, bacterial gill disease, zooplankton (cnidarian nematocyst)‐associated gill disease, harmful algal gill disease and chemical/toxin‐associated gill disease. The term ‘multifactorial gill disease’ is used when multiple distinguishable types of disease (as opposed to an obvious single primary type) are present. When gill disease is non‐specific, it is referred to as ‘complex gill disease’ (CGD) or ‘complex gill disorder’. These two terms are often used interchangeably and are overlapping. The significance of many infectious and non‐infectious agents that may be associated with CGD is often unclear. In this review, we summarise aspects of the different types of gill disease that are relevant to the epidemiology of gill disease and of CGD in particular. We also tabulate simultaneously occurring putative pathogens to explore the multifactorial nature of gill disease.

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“…Paramoeba perurans was reported in wild fish from Norway as well as in cleaner fish and as a result of experimental studies, we have a better understanding of the potential role of wild fish as a reservoir (Haugland, Olsen, Rønneseth, & Andersen, ; Hellebø, Stene, & Aspehaug, ). PCR detection of P. perurans in the environmental samples (water, biofilm, plankton, several filter feeders) and wild fish around the AGD‐affected farms growing Atlantic salmon has been reported (Hellebø, Stene, & Aspehaug, ; Wright, Nowak, Oppedal, & Bridle, ; Wright, Nowak, Oppedal, & Bridle, ).…”

Section: Synthesis Of Information About Infectious Agentsmentioning

confidence: 99%

Review of infectious agent occurrence in wild salmonids in British Columbia, Canada

Jia

Delphino

Awosile

et al. 2019

Journal of Fish Diseases

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Wild Pacific salmonids (WPS) are economically and culturally important to the Pacific North region. Most recently, some populations of WPS have been in decline. Of hypothesized factors contributing to the decline, infectious agents have been postulated to increase the risk of mortality in Pacific salmon. We present a literature review of both published journal and unpublished data to describe the distribution of infectious agents reported in wild Pacific salmonid populations in British Columbia (BC), Canada. We targeted 10 infectious agents, considered to potentially cause severe economic losses in Atlantic salmon or be of conservation concern for wild salmon in BC. The findings indicated a low frequency of infectious hematopoietic necrosis virus, piscine orthoreovirus, viral haemorrhagic septicaemia virus, Aeromonas salmonicida, Renibacterium salmoninarum, Piscirickettsia salmonis and other Rickettsia-like organisms, Yersinia ruckeri, Tenacibaculum maritimum and Moritella viscosa. No positive results were reported for infestations with Paramoeba perurans in peer-reviewed papers and the DFO Fish Pathology Program database. This review synthesizes existinginformation, as well as gaps therein, that can support the design and implementation of a long-term surveillance programme of infectious agents in wild salmonids in BC. K E Y W O R D SBritish Columbia, historical review, infectious agents, wild Pacific salmonids

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Free-living Neoparamoeba perurans depth distribution is mostly uniform in salmon cages, but reshaped by stratification and potentially extreme fish crowding

Cited by 13 publications

References 43 publications

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

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

Epidemiology of marine gill diseases in Atlantic salmon (Salmo salar) aquaculture: a review

Review of infectious agent occurrence in wild salmonids in British Columbia, Canada

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