scholarly journals Changes in the Splenic Melanomacrophage Centre Surface Area in Southern Bluefin Tuna (Thunnus maccoyii) Are Associated with Blood Fluke Infections

Pathogens ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 79
Author(s):  
Barbara F. Nowak ◽  
Mai Dang ◽  
Claire Webber ◽  
Lukas Neumann ◽  
Andrew Bridle ◽  
...  
Keyword(s):  
Surface Area ◽  
Bluefin Tuna ◽  
Its2 Rdna ◽  
Farmed Fish ◽  
Blood Fluke ◽  
Blood Flukes ◽  
Copy Numbers ◽  
Southern Bluefin Tuna ◽  
Gill Filaments ◽  
Pre Treatment

Melanomacrophage centres (MMCs) are aggregates of macrophages accumulating various pigments. They have been proposed as an indicator of fish immune response. Blood flukes are common parasites in farmed fish. Two cohorts of wild Southern Bluefin Tuna (Thunnus maccoyi) were examined at transfer, before treatment against blood flukes (pre-treatment) and at harvest. MMCs were assessed in histological sections using image analysis, while Cardicola forsteri and Cardicola orientalis infection severity was determined using qPCR, count of adult flukes in heart flushes and count of eggs in gill filaments. Fish from both cohorts showed the same pattern in the changes in the surface area of MMCs. The surface area of splenic MMCs increased over the ranching duration and was positively correlated to the PCR determined copy numbers of Cardicola forsteri ITS2 rDNA in the gills of those fish. However, the infection with blood fluke was more variable, both between cohorts and individuals within the same cohort. Eggs of blood fluke were detected in renal MMCs using histology. Cardicola forsteri had a higher prevalence than Cardicola orientalis. This study contributes to our understanding of blood fluke infections in Southern Bluefin Tuna and their interactions with MMCs.

scholarly journals Correlation of Humoral Immune Response in Southern Bluefin Tuna, T. maccoyii, with Infection Stage of the Blood Fluke, Cardicola forsteri

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e45742 ◽  
Author(s):  
Nicole T. Kirchhoff ◽  
Melanie J. Leef ◽  
Victoria Valdenegro ◽  
Craig J. Hayward ◽  
Barbara F. Nowak
Keyword(s):  
Immune Response ◽  
Humoral Immune Response ◽  
Bluefin Tuna ◽  
Blood Fluke ◽  
Humoral Immune ◽  
Southern Bluefin Tuna ◽  
Infection Stage

scholarly journals First Report of Blood Fluke Pathogens with Potential Risk for Emerging Yellowtail Kingfish (Seriola lalandi) Aquaculture on the Chilean Coast, with Descriptions of Two New Species of Paradeontacylix (Aporocotylidae)

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 849
Author(s):  
Fabiola A. Sepúlveda ◽  
Luis A. Ñacari ◽  
Maria Teresa González
Keyword(s):  
New Species ◽  
Phylogenetic Trees ◽  
Principal Component ◽  
Farmed Fish ◽  
Blood Fluke ◽  
Blood Flukes ◽  
Southeastern Pacific ◽  
Two New Species ◽  
Yellowtail Kingfish ◽  
Seriola Lalandi

Blood flukes are digeneans that infect wild and farmed fish that can cause a severe and potentially lethal disease in farmed fish. These parasites are undetectable in the larval stage based on macroscopic observations in the definitive host with the infection becoming evident when eggs accumulate in the branchial vessels. There are nine known species of the genus Paradeontacylix and seven exclusively parasitize Seriola spp. from several geographical areas. Seriola lalandi aquaculture farms are emerging at various localities in northern Chile. Here, we report, for the first time, two blood fluke species parasitizing S. lalandi in the Southeastern Pacific (Chile). In the laboratory, the gills and heart of fish were removed. The retained blood flukes were separated according to the infection site, fixed in 70% or 95% ethanol for taxonomic and molecular analysis, respectively. Morphometrical differences among the fluke species were evaluated with a principal component analysis (PCA) using proportional body measurements. Phylogenetic trees were constructed based on 28S rDNA, cox1 mDNA using Bayesian inference (BI), and maximum likelihood (ML). Based on morphology, morphometry, and molecular analyses, two new species are proposed: P. humboldti n. sp. from the gills and P. olivai n. sp. from the heart of S. lalandi. Both were clearly distinguished from other species of Paradeontacylix by a combination of morphologic features (posterior tegumental spines, testes arrangement, body size). The genetic distance (based on cox1) among species was >10%. P. humboldti n. sp. and P. olivai n. sp. are sister species (with a common ancestor) independent of P. godfreyi from S. lalandi in Australia. The newly identified parasites may pose a risk to farmed S. lalandi as aporocotylids have been the cause of diseases in farmed fish from other geographical areas. In addition, some cages of S. lalandi are currently maintained in an open circulating system, which could favor the transmission of these parasites (if involved hosts are present in the environment).

Serological evidence of an antibody response in farmed southern bluefin tuna naturally infected with the blood fluke Cardicola forsteri

2008 ◽  
Vol 25 (1-2) ◽  
pp. 66-75 ◽  
Author(s):  
Hamish M. Aiken ◽  
Craig J. Hayward ◽  
Philip Crosbie ◽  
Marianne Watts ◽  
Barbara F. Nowak
Keyword(s):  
Antibody Response ◽  
Bluefin Tuna ◽  
Serological Evidence ◽  
Blood Fluke ◽  
Southern Bluefin Tuna

scholarly journals Prevalence and Intensity of Cardicola spp. Infection in Ranched Southern Bluefin Tuna and a Comparison of Diagnostic Methods

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1248
Author(s):  
Cecilia Power ◽  
Shannon Evenden ◽  
Kirsten Rough ◽  
Claire Webber ◽  
Maree Widdicombe ◽  
...  
Keyword(s):  
Best Practice ◽  
Quantitative Polymerase Chain Reaction ◽  
Parasite Load ◽  
Bluefin Tuna ◽  
Diagnostic Methods ◽  
Health Concern ◽  
Infection Prevalence ◽  
Adult Fluke ◽  
Blood Fluke ◽  
Southern Bluefin Tuna

The parasitic blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for Southern Bluefin Tuna Thunnus maccoyii (SBT) ranched in Australia. In this study we compared the effect of treatment, company, and ranching year on blood fluke infections in ranched SBT. SBT were sampled during the 2018 and 2019 ranching seasons from praziquantel (PZQ) treated pontoons and untreated pontoons managed by two companies. Severity of infection was diagnosed by several criteria including adult fluke counts from hearts, egg counts from gill filaments and the use of specific quantitative polymerase chain reaction (qPCR) for detection of C. forsteri and C. orientalis ITS-2 DNA in SBT hearts and gills. PZQ treatment remains highly effective against C. forsteri infection. Prevalence and intensity of Cardicola spp. infection was lower in 2019 than 2018 for Company A in treated pontoons at week 12 and week 17 of ranching, and lower for Company A than Company B in untreated pontoons at month 5 of ranching. Results indicate re-infection may be less likely in the environment near Company A pontoons, and consistent years of treatment may have lowered the parasite load in the environment. qPCR demonstrated higher sensitivity when comparing diagnostic methods for C. forsteri in heart, and higher specificity when comparing diagnostic methods for Cardicola spp. in gills. Continuing to monitor blood fluke infections in ranched SBT can help to detect changes in drug efficacy over time and help industry to develop a best practice for treatment.

Concurrent epizootic hyperinfections of sea lice (predominantly Caligus chiastos) and blood flukes (Cardicola forsteri) in ranched Southern Bluefin tuna

2010 ◽  
Vol 173 (1-2) ◽  
pp. 107-115 ◽  
Author(s):  
Craig J. Hayward ◽  
David Ellis ◽  
Danielle Foote ◽  
Ryan J. Wilkinson ◽  
Phillip B.B. Crosbie ◽  
...  
Keyword(s):  
Bluefin Tuna ◽  
Sea Lice ◽  
Blood Flukes ◽  
Southern Bluefin Tuna

scholarly journals The Southern Bluefin Tuna mucosal microbiome is influenced by husbandry method, net pen location, and anti-parasite treatment

2020 ◽  
Author(s):  
Jeremiah J Minich ◽  
Cecilia Power ◽  
Michaela Melanson ◽  
Rob Knight ◽  
Claire Webber ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Fish Species ◽  
Bluefin Tuna ◽  
Farmed Fish ◽  
Microbiome Composition ◽  
Southern Bluefin Tuna ◽  
Yellowtail Kingfish ◽  
Seriola Lalandi ◽  
And Function ◽  
The Impact

AbstractAquaculture is the fastest growing primary industry worldwide. Marine finfish culture in open ocean net pens, or pontoons, is one of the largest growth areas and is currently the only way to rear high value fish such as bluefin tuna. Ranching involves catching wild juveniles, stocking in floating net pens and fattening for four to eight months. Tuna experience several parasite-induced disease challenges in culture that can be mitigated by application of praziquantel (PZQ) as a therapeutic. In this study, we characterized the microbiome of ranched southern Bluefin Tuna, Thunnus maccoyii, across four anatomic sites (gill, skin, digesta, and anterior kidney) and evaluated environmental and pathological factors that influence microbiome composition, including the impact of PZQ treatment on microbiome stability. Southern bluefin tuna gill, skin, and digesta microbiome communities are unique and potentially influenced by husbandry practices, location of pontoon growout pens, and treatment with the antiparasitic PZQ. There was no significant relationship between the fish mucosal microbiome and incidence or abundance of adult blood fluke in the heart or fluke egg density in the gill. An enhanced understanding of microbiome diversity and function in high-value farmed fish species such as bluefin tuna is needed to optimize fish health and improve aquaculture yield. Comparison of the bluefin tuna microbiome to other fish species, including Seriola lalandi (yellowtail kingfish), a common farmed species from Australia, and Scomber japonicus (Pacific mackerel), a wild caught Scombrid relative of tuna, showed the two Scombrids had more similar microbial communities compared to other families. The finding that mucosal microbial communities are more similar in phylogenetically related fish species exposes an opportunity to develop mackerel as a model for tuna microbiome and parasite research.

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