The gill parasite Paramoeba perurans compromises aerobic scope, swimming capacity and ion balance in Atlantic salmon

Hvas, Malthe; Karlsbakk, Egil; Mæhle, Stig; Wright, Daniel; Oppedal, Frode

doi:10.1093/conphys/cox066

Cited by 57 publications

(55 citation statements)

References 66 publications

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“…Despite no clinical signs in infested fish being observed in this study and the connection between gill lesions and pathophysiological effects remaining poorly understood (Ferguson & Speare, ), our results would suggest some negative consequences on fish performance. The proliferative lesions and oedema observed in this study increase the diffusion distance and reduce the surface area of the water–blood barrier, compromising the gas exchange (Hvas, Karlsbakk, Mæhle, Wright & Oppedal, ). In addition, the epithelial degeneration and erosion related to the parasite detachment could increase the epithelial permeability and consequently it might enable secondary infections or osmoregulatory disbalances, as described in other gill diseases (Hvas et al, ; Powell, Carson & van Gelderen, ).…”

Section: Discussionmentioning

confidence: 88%

“…The proliferative lesions and oedema observed in this study increase the diffusion distance and reduce the surface area of the water–blood barrier, compromising the gas exchange (Hvas, Karlsbakk, Mæhle, Wright & Oppedal, ). In addition, the epithelial degeneration and erosion related to the parasite detachment could increase the epithelial permeability and consequently it might enable secondary infections or osmoregulatory disbalances, as described in other gill diseases (Hvas et al, ; Powell, Carson & van Gelderen, ). However, as a result of the early larval rejection, the parasitism was localized in clusters and below 300 glochidia/fish g, following the recommendations for artificial breeding of this naiad (Taeubert & Geist, ).…”

Section: Discussionmentioning

confidence: 88%

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Early stages of Margaritifera margaritifera glochidiosis in Atlantic salmon: Morphopathological characterization

Castrillo

Varela‐Dopico

Ondina

et al. 2019

Journal of Fish Diseases

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Freshwater mussels of the order Unionida encyst into the fish mucosa to metamorphose and complete their life cycle, causing a parasitic disease known as glochidiosis. This parasitic stage represents a bottleneck for the survival of naiads, particularly for critically endangered species as Margaritifera margaritifera; however, little is known about the events occurring during this critical stage. Therefore, this study aimed to histologically characterize the development of M. margaritifera glochidiosis in Atlantic salmon to get insight into the pathogenesis of this interaction. Fish exposed to glochidia were sampled during the first 44 days post‐exposure, and organs were observed by stereomicroscopy and light microscopy. Glochidia attached to the gills by pinching the lamellar epithelium, whereupon an acute proliferative branchitis engulfed most of the larvae. However, during the first 14 days, a severe detachment of unviable glochidia occurred, associated with the presence of pleomorphic inflammatory infiltrate and epithelial degeneration. In the cases where larvae remained attached, a chronification of the lesions with none to scarce inflammation was observed. These results provide key information to better understand the complex host–parasite interaction during the early stages of glochidiosis and provide valuable information to optimize artificial rearing of naiads in conservation of threatened freshwater mussel populations.

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Section: Discussionmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 88%

Early stages of Margaritifera margaritifera glochidiosis in Atlantic salmon: Morphopathological characterization

Castrillo

Varela‐Dopico

Ondina

et al. 2019

Journal of Fish Diseases

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“…) can arise, which can reduce the metabolic capacity of salmon (Hvas et al . ). It is also possible that other diseases (e.g.…”

Section: Discussionmentioning

confidence: 97%

Salmon lice treatments and salmon mortality in Norwegian aquaculture: a review

Overton

Dempster

Oppedal

et al. 2018

Reviews in Aquaculture

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214

162

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With the expansion of Atlantic salmon aquaculture, the economic and ecological impacts of salmon lice (Lepeophtheirus salmonis) has increased. Norway battles this problematic parasite with various control and preventative methods within farms. We analysed two national-level databases to examine the number of operations reported each year from 2012 to 2017 and salmon mortality rates attributable to each operation type. From 2012 to 2017, 1.4 times more operations were registered, despite only limited increases in biomass produced across this period. We detected a rapid and recent paradigm shift in the industry's approach to lice control from chemotherapeutant to non-medicinal operations. Chemotherapeutants (azamethiphos, cypermethrin, deltamethrin and hydrogen peroxide) dominated operations from 2012 to 2015 (>81%), while mechanical and thermal treatments dominated in 2016 and 2017 (>40% and >74%, respectively). Thermal operations caused greatest mortality increases (elevated mortality for 31% of treatments), followed by mechanical (25%), hydrogen peroxide (21%), and azamethiphos, cypermethrin and deltamethrin (<14%). Temperature, fish size and pre-existing mortality rates all influenced post-treatment mortality outcomes. For chemotherapeutants, mortality increased as sea temperature increased. For mechanical and thermal treatments, mortalities increased at low (4-7°C) and high (13-16°C) temperatures. Fish with high pre-existing mortality (0.25-1.0% mortality the month before treatment) experienced increased mortality after treatment, and large fish (≥2 kg) were more susceptible to increased mortality than small (<2 kg). Generally, thermal, mechanical and hydrogen peroxide operations performed better in 2017 compared to 2015 and 2016, as the percentage of mortality observations were lower. With mechanical and thermal treatments now predominant, future research and industry development should prioritise reducing mortality and improving post-treatment outcomes.

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“…In addition, U crit of larger Atlantic salmon Salmo salar have been reported as high as 125 cm s −1 (Hvas et al 2017b), while the 'very strong' class is based on results for small post-smolts swimming at 3°C, which represent the conditions of poorest swimming capacity. Furthermore, the presence of diseases or parasites may lead to a further reduction of U crit (Hvas et al 2017c). Ideally, the 'very strong' class should reflect the specific species in question, body size and ambient temperature and account for inherent variation in swimming capacities in the population so that weaker individuals are protected.…”

Section: Current Class Definitions Based On Fish Behaviourmentioning

confidence: 99%

Fish welfare based classification method of ocean current speeds at aquaculture sites

Jónsdóttir¹,

Hvas²,

Alfredsen³

et al. 2019

Aquacult. Environ. Interact.

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A major trend in marine aquaculture is to move production to more exposed sites with occasionally rough ocean current events. However, it is unclear whether fish will thrive in these extreme environments, since thorough descriptions of ambient current conditions with regards to fish welfare is lacking. In the present study, ocean current data were collected using acoustic Doppler current profilers at 5 exposed sites along the Norwegian coast over minimum periods of 5 mo. To evaluate welfare risks, current data was compared to known limits of swimming capabilities, such as onset of behavioural changes and critical swimming speeds (U crit ), of Atlantic salmon Salmo salar and lumpfish Cyclopterus lumpus. Specifically, at each site, current speeds were classified into 6 categories based on expected impact on swimming behaviours of Atlantic salmon, and duration of currents within each category were inspected using a homogeneous and non-homogeneous criterion for the water column. Current speeds were then compared with projected U crit at relevant temperatures and fish sizes of Atlantic salmon and lumpfish. Furthermore, a detailed characterization of extreme events at the most exposed site was performed. Of the 5 locations, only 1 exceeded the U crit of Atlantic salmon, while all sites featured currents above U crit of lumpfish for up to 33 h at a time. These results suggest that responsible Atlantic salmon farming is possible at sites considered exposed, while lumpfish should be restricted to more sheltered environments. The presented method can be applied for other aquaculture fish species if adequate data are available.

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The gill parasite Paramoeba perurans compromises aerobic scope, swimming capacity and ion balance in Atlantic salmon

Abstract: A cosmopolitan non-species specific gill parasite associated with finfish aquaculture and high temperatures compromises gill functionality and swimming abilities in Atlantic salmon. Interactions with environmental warming are expected to amplify the pathophysiology of this parasite.

Cited by 57 publications

References 66 publications

Early stages of Margaritifera margaritifera glochidiosis in Atlantic salmon: Morphopathological characterization

Early stages of Margaritifera margaritifera glochidiosis in Atlantic salmon: Morphopathological characterization

Salmon lice treatments and salmon mortality in Norwegian aquaculture: a review

Fish welfare based classification method of ocean current speeds at aquaculture sites

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