Fish Health Laboratory

South Perth, Australia

Fish Health Laboratory

South Perth, Australia
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Bastos Gomes G.,James Cook University | Hutson K.S.,James Cook University | Domingos J.A.,James Cook University | Domingos J.A.,Bribie Island Research Center | And 5 more authors.
Aquaculture | Year: 2017

Globally, disease accounts for around 40% of lost aquaculture production. Commonly, disease occurs due to an inability of farm managers to accurately quantify disease risk due to the abundance of the pathogenic agent in their production systems, along with a poor understanding of how outbreaks are linked to changes in water quality parameters. Environmental DNA (eDNA) sampling methodology associated with molecular techniques is suited to rapidly assess the background presence of pathogens in fish farms, thereby providing managers with critical information that can be used to mitigate disease threats. Adopting the ciliate protozoan Chilodonella hexasticha as a model, this study examined the relationship between environmental DNA of C. hexasticha, critical water parameters and the occurrence of disease outbreaks on a commercial barramundi Lates calcarifer farm, where water was sampled monthly over a 1 year timeframe. A qPCR assay based on the small subunit ribosomal DNA gene was used to monitor the abundance of C. hexasticha in pond water (SSU-rDNA copies/μL). Increased C. hexasticha eDNA levels were found to be highly correlated with occurrence of later fish mortality events (r = 0.402; P < 0.001) and also with size of fish (r = − 0.189; P < 0.05); smaller fish were more prone to being impacted by an epizootic of the parasite. However, no correlations were found between any of the water quality parameters measured (rainfall, water temperature and dissolved oxygen) and abundance of this parasite, although there were significantly more fish mortalities observed during the warmer, wetter monsoonal season compared to the cooler, dry season (1280 vs. 135 mortalities, respectively; P < 0.05). This study highlights the potential of an eDNA approach as a management tool to quickly assess parasite loads in water and minimise the risk of disease outbreaks in aquaculture systems. © 2017 Elsevier B.V.


Yong R.Q.-Y.,University of Queensland | Cutmore S.C.,University of Queensland | Miller T.L.,James Cook University | Miller T.L.,Fish Health Laboratory | And 2 more authors.
Systematic Parasitology | Year: 2016

Two new species of Cardicola Short, 1953 are described from the milkfish, Chanos chanos Forsskål (Gonorynchiformes: Chanidae), obtained from off Lizard Island on the northern Great Barrier Reef (GBR) and North Stradbroke Island in southeast Queensland. These are the first known blood flukes from this order of fishes. Cardicola suni n. sp. differs from all other Cardicola spp. by a combination of a large ovoid oral sucker surrounding a subterminal mouth, recurved tegumental spines up to 16 μm long, anterior caeca occupying 25.1–31.3% (28.7%) of total body length and a mostly-intercaecal ovary. Cardicola jiigurru n. sp. differs from C. suni n. sp. and all other species of Cardicola by a combination of a narrowly lanceolate body, weakly-muscularised and poorly-demarcated oral sucker, minute tegumental spines <1 µm in length, and anterior caeca occupying 15.9–22.0% (19.4%) of total body length, an almost entirely post-caecal ovary and the male genital pore terminal on a dorsolateral protuberance. A third species, closely resembling C. suni n. sp., was also discovered off Wangetti Beach, north Queensland, but is not described due to lack of material. Molecular phylogenetic analysis, based on both ITS2 and partial 28S rDNA regions, shows that these three species form a clade nested within that formed by existing species of Cardicola. © 2016, Springer Science+Business Media Dordrecht.


Blasco-Costa I.,Natural History Museum of Geneva | Cutmore S.C.,University of Queensland | Miller T.L.,Fish Health Laboratory | Miller T.L.,James Cook University | Nolan M.J.,Royal Veterinary College University of London
Systematic Parasitology | Year: 2016

To date, morphological analysis has been the cornerstone to trematode systematics. However, since the late-1980s we have seen an increased integration of genetic data to overcome problems encountered when morphological data are considered in isolation. Here, we provide advice regarding the ‘best molecular practice’ for trematode taxonomy and systematic studies, in an attempt to help unify the field and provide a solid foundation to underpin future work. Emphasis is placed on defining the study goals and recommendations are made regarding sample preservation, extraction methods, and the submission of molecular vouchers. We advocate generating sequence data from all parasite species/host species/geographic location combinations and stress the importance of selecting two independently evolving loci (one ribosomal and one mitochondrial marker). We recommend that loci should be chosen to provide genetic variation suitable to address the question at hand and for which sufficient ‘useful’ comparative sequence data already exist. Quality control of the molecular data via using proof-reading Taq polymerase, sequencing PCR amplicons using both forward and reverse primers, ensuring that a minimum of 85% overlap exists when constructing consensus sequences, and checking electropherograms by eye is stressed. We advise that all genetic results are best interpreted using a holistic biological approach, which considers morphology, host identity, collection locality, and ecology. Finally, we consider what advances next-generation sequencing holds for trematode taxonomy and systematics. © 2016, Springer Science+Business Media Dordrecht.


Bastos Gomes G.,James Cook University | Miller T.L.,James Cook University | Miller T.L.,Fish Health Laboratory | Vaughan D.B.,James Cook University | And 3 more authors.
Veterinary Parasitology | Year: 2017

Parasitic Chilodonella species, Chilodonella piscicola and Chilodonella hexasticha, cause considerable economic losses globally to freshwater farmed fish production. Some genetic studies of Chilodonella spp. have indicated that many species within the genus may form cryptic species complexes. To understand the diversity of Chilodonella spp. infecting Australian freshwater farmed fish, specimens were isolated from infected barramundi (Lates calcarifer) and Murray cod (Maccullochella peelii) from fish farms in tropical north Queensland (QLD), temperate Victoria (Vic) and New South Wales (NSW) for genetic and morphological analysis. Parasites were stained and measured for morphological description and comparative phylogenetic analyses were performed using the mitochondrial small subunit (mtSSU) rDNA marker. Morphological analyses revealed four distinct morphotypes of Chilodonella infecting farmed barramundi and Murray Cod. Three putative species were isolated from barramundi (Chilodonella hexasticha, C. acuta and C. uncinata) and one from Murray cod (C. piscicola). However, phylogenetic analyses detected only three distinct genotypes, with the putative C. hexasticha and C. piscicola sharing 100% sequence identity. This suggests that Australian isolates of C. hexasticha and C. piscicola could represent the same species and may exhibit phenotypic plasticity. Further molecular analysis, including isolates from the type localities, should be performed to support or refute the synonymy of these species. © 2017 Elsevier B.V.


Gibson-Kueh S.,Murdoch University | Chee D.,Animal and Plant Health Laboratories | Chen J.,Animal and Plant Health Laboratories | Wang Y.H.,Animal and Plant Health Laboratories | And 6 more authors.
Journal of Fish Diseases | Year: 2012

This is the first pathological description of 'scale drop syndrome' (SDS) in Asian seabass, Lates calcarifer Bloch. Cumulative mortality was estimated at 40-50%. The vasculitis in all major organs including the skin and associated tissue necrosis was distinctive. The dermis overlying scale beds was often necrotic and associated with scale loss. Necrosis of splenic ellipsoids, renal glomeruli and choroid rete glands of eye were further hallmarks of a disease with systemic vascular involvement. The brain was not spared vascular damage, and the resulting multifocal encephalomalacia probably accounts for the spiral swimming behaviour in some affected fish. Other lesions included accentuated hepatic lobulation and gastric gland necrosis. Nuclear chromatin margination and karyolysis in hepatocytes, renal tubular epithelium and gastric and intestinal epithelium suggest specific targeting of cells. Basophilic cytoplasmic inclusions were present in spleen, kidney, liver, heart and choroid rete, but they were not prominent. Using transmission electron microscopy, two morphological forms of virions were observed: single- and double-enveloped hexagonal virions. Based on size and morphology, these virions resemble iridovirus or herpesvirus. The cause of SDS is unknown, but the pathological changes, especially the vasculitis, suggest an infectious aetiology, possibly viral. © 2011 Blackwell Publishing Ltd.


Gibson-Kueh S.,Murdoch University | Yang R.,Murdoch University | Thuy N.T.N.,Minh Hai Sub Institute for Fisheries Research | Jones J.B.,Fish Health Laboratory | And 2 more authors.
Veterinary Parasitology | Year: 2011

An intestinal Eimeria was previously reported as a significant pathogen of Asian seabass (Lates calcarifer) in nurseries in Vietnam. In the present study, both Eimeria and Cryptosporidium were detected by sequence analyses of fragments of the 18S rRNA gene amplified from these Vietnamese L. calcarifer tissues. Based on these analyses, the Eimeria from the Vietnamese L. calcarifer formed clades with the Eimeria detected in L. calcarifer tissues from Australia, but clustered separately from other known Eimeria and Goussia species. The Cryptosporidium detected in L. calcarifer from Vietnam clustered closest with C. parvum and C. hominis. In situ hybridization using DIG-labeled DNA probes generated from 18S PCR products on the Vietnamese L. calcarifer wax block tissues showed that this method could not be used to distinguish between Eimeria and Cryptosporidium, due to the conserved nature of the 18S locus. A previously published study on the morphology of parasite developmental stages and oocysts in the Vietnamese L. calcarifer tissues showed only an intestinal Eimeria infection. The Cryptosporidium could be present at very low levels undetectable by microscopy in intestines, or being ubiquitous, was a possible contaminant from feed or water. While molecular analysis is a very useful tool in the study of disease and identification of aetiological agents, this study reiterates the importance of demonstrating organisms in situ in tissues. © 2011 Elsevier B.V.


Yong R.Q.-Y.,University of Queensland | Cutmore S.C.,University of Queensland | Bray R.A.,Natural History Museum in London | Miller T.L.,Fish Health Laboratory | And 5 more authors.
Parasitology International | Year: 2016

We describe three new species of blood flukes (Aporocotylidae) and propose their classification within the genus Psettarium Goto & Ozaki, 1929. All three species were collected from the circulatory systems of pufferfishes caught off Bali, central Indonesia. Psettarium pulchellum n. sp. was found in the gills of both the narrow-lined puffer (Arothron manilensis de Procé) and the spiny blaasop (Tylerius spinosissimus Regan), while P. ogawai n. sp. and P. jimbaranense n. sp. were found in the gills of the reticulated puffer (Arothron reticularis Bloch & Schneider). The morphological characteristics of these taxa necessitated emendation of the diagnosis for the genus Psettarium, to accommodate the presence of an oral sucker, multiple or entirely post-caecal testes and a degenerate posterior testis. Features such as proportion of body length occupied by the oesophagus, and posterior caeca being ≥. 7. × the length of anterior caeca, are no longer regarded as useful genus-level characters. Additionally, Sasala nolani is reassigned to this genus as Psettarium nolani n. comb. In phylogenetic analyses of the 28S and ITS2 rDNA regions, all three new taxa form a well-supported clade, together with Psettarium sinense and Psettarium nolani n. comb., the two other species of tetraodontid-infecting aporocotylids for which comparative rDNA data were available. The short branch lengths within this clade, despite dramatic morphological differences between the five species, suggest that rapid morphological diversification has occurred among the tetraodontid-infecting aporocotylids. The genus Psettarium has long been considered problematic. Further commentary is given on the history of this genus and how the issues presented might be resolved. © 2016 Elsevier Ireland Ltd.


PubMed | Fish Health Laboratory, University of Queensland, Natural History Museum of Geneva and Royal Veterinary College University of London
Type: Journal Article | Journal: Systematic parasitology | Year: 2016

To date, morphological analysis has been the cornerstone to trematode systematics. However, since the late-1980s we have seen an increased integration of genetic data to overcome problems encountered when morphological data are considered in isolation. Here, we provide advice regarding the best molecular practice for trematode taxonomy and systematic studies, in an attempt to help unify the field and provide a solid foundation to underpin future work. Emphasis is placed on defining the study goals and recommendations are made regarding sample preservation, extraction methods, and the submission of molecular vouchers. We advocate generating sequence data from all parasite species/host species/geographic location combinations and stress the importance of selecting two independently evolving loci (one ribosomal and one mitochondrial marker). We recommend that loci should be chosen to provide genetic variation suitable to address the question at hand and for which sufficient useful comparative sequence data already exist. Quality control of the molecular data via using proof-reading Taq polymerase, sequencing PCR amplicons using both forward and reverse primers, ensuring that a minimum of 85% overlap exists when constructing consensus sequences, and checking electropherograms by eye is stressed. We advise that all genetic results are best interpreted using a holistic biological approach, which considers morphology, host identity, collection locality, and ecology. Finally, we consider what advances next-generation sequencing holds for trematode taxonomy and systematics.


Nolan M.J.,Royal Veterinary College University of London | Cantacessi C.,University of Cambridge | Cutmore S.C.,University of Queensland | Cribb T.H.,University of Queensland | And 2 more authors.
Parasitology International | Year: 2016

We report a new species of aporocotylid trematode (Platyhelminthes: Digenea) from the heart of the orangelined cardinalfish, Taeniamia fucata (Cantor), from off Heron Island on the southern Great Barrier Reef. We used an integrated approach, analysing host distribution, morphology, and genetic data from the internal transcribed spacer 2 of the ribosomal DNA, to circumscribe Phthinomita heinigerae n. sp. This is the first species of Phthinomita Nolan & Cribb, 2006 reported from the Apogonidae; existing species and known 'types' are recorded from species of the Labridae, Mullidae, and Siganidae. The new species is distinguished from its 11 congeners in having a body 2977-3539 long and 16.5-22.4 times longer than wide, an anterior testis 6.2-8.2 times longer than wide and 8.3-13.0 times longer than the posterior testis, a posterior testis whose width is 35-56% of the body width, and an ovary positioned 11-13% of the body length from the posterior end, and is entirely anterior to the posterior margin of the anterior testis. In addition, 2-34 base differences (0.4-7.0% sequence divergence over 485 base positions) were detected among the ITS2 sequence representing P. heinigerae n. sp. and the 14 representing other Phthinomita species/molecular types. Prevalence and intensity of infection with P. heinigerae n. sp. was relatively high within the heart tissue of T. fucata, with 19 of 20 fish examined from off Heron Island infected (95%) with 7-25 adult worms (arithmetic mean 16.6). Infections by these parasites accounted for an occupation of 7-30% of the total estimated heart volume. © 2016 Elsevier Ireland Ltd.


Nolan M.J.,Royal Veterinary College University of London | Curran S.S.,University of Southern Mississippi | Miller T.L.,Fish Health Laboratory | Cutmore S.C.,University of Queensland | And 2 more authors.
Parasitology International | Year: 2015

Two new species of bucephalid trematode (Platyhelminthes: Digenea) are described from the giant moray eel, Gymnothorax javanicus (Anguilliformes: Muraenidae), from off Lizard Island, Australia. We used a combined morphological and molecular-based approach targeting the internal transcribed spacer 2 (ITS2) of the ribosomal DNA (rDNA) and the D1-D3 region of the large subunit (28S) of rDNA to circumscribe the species. Dollfustrema durum n. sp. is distinguished from seven congeners in having 5-6 rows of enlarged body spines circling the anterior portion of the rhynchus. From the remaining 10 species, D. durum n. sp. differs in body length, and in having a caecum that terminates posteriorly to the confluent arc formed by the vitelline follicles, gonads predominantly anterior to the pharynx, testes in tandem, an anterior testis positioned posteriorly to the vitelline follicles, and the pre-vitelline field 23-40% of the body length. Heterobucephalopsis perardua n. sp. differs from Heterobucephalopsis gymnothoracis, the type- and only other reported species, in being two to three times smaller. Heterobucephalopsis, currently considered a genus inquirendum, is confirmed as valid and is rediagnosed. Bayesian inference analysis of 28S rDNA sequences representing 28 species from nine genera and four subfamilies of bucephalid, indicates that i) subfamily classifications previously based on morphological characters are broadly robust, ii) the sequence representing H. perardua n. sp. is resolved as distinct, and basal, to sequences representing the Bucephalinae, the Prosorhynchinae, the Paurorhynchinae, and the Dolichoenterinae, iii) the Dolichoenterinae and the Prosorhynchinae are monophyletic sister clades, basal to the Bucephalinae and the Paurorhynchinae, iv) sequences representing Grammatorcynicola, Prosorhynchus, and Dollfustrema are also monophyletic, v) the Bucephalinae is paraphyletic relative to the Paurorhynchinae, and vi) the bucephaline genera Prosorhynchoides, Rhipidocotyle, and Bucephalus are each polyphyletic. The morphological and molecular differences observed among the four previously recognised subfamilies in this study lead us to propose Heterobucephalopsinae n. subfam. to accommodate the genus Heterobucephalopsis. © 2015 Elsevier Ireland Ltd.

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