Lab

Marine Parasitology Laboratory

Institution: Cawthron Institute

Featured research (3)

Tenacibaculum maritimum is a cosmopolitan bacterial pathogen with the potential to cause significant losses in a broad range of farmed and wild marine fish species. This study investigated the antigenic diversity of T. maritimum isolated in culture from farmed Chinook (king) salmon (Oncorhynchus tshawytscha) from the Marlborough Sounds in New Zealand. A total of 36 isolates were examined using antibody serotyping and rapid molecular serotyping via multiplex PCR (mPCR) targeting genes encoding O-antigen biosynthesis enzymes. Serological analysis using three different polyclonal antisera developed against T. maritimum isolated from farmed Atlantic salmon (Salmo salar) in Tasmania, Australia revealed that there are three putative serotypes of T. maritimum that occur in New Zealand. The predominant serotype was defined by a positive reaction to all three Tasmanian antisera (antisera A, B and C), designated as serotype ABC. This serotype was found at all nine farm locations tested and represented 81% of all isolates examined. The same library of isolates was evaluated by mPCR serotyping and found three O-AGC types among tested isolates. O-AGC Type 3 was not only the predominant type (72%) present, but it also had a wide distribution, having been isolated at eight of the nine farms. Two other O-AGC types (O-AGC Type 2–1 and O-AGC Type 3–2) were identified, providing evidence of genetic variation. However, there was only partial concordance between the two serotyping techniques, which is likely linked to differences in the way serotypes are defined in the two approaches that were used. Nevertheless, in broad terms there is good evidence of intraspecific antigenic variation within our library of isolates, and collectively these data will be of crucial importance for assessing the pathogenicity of the isolates and the subsequent development of a vaccine for this emerging disease in New Zealand marine salmon farms.
Globally coral reefs are in decline, largely driven by local anthropogenic pressures combined with broader cumulative impacts from climate change. Coral aquaculture will play an important role in active reef restoration and attempts to preserve some semblance of coral reefs in highly impacted areas. Achieving maximum growth and survivorship of cultured corals is necessary to achieve optimal results. This is not possible without the study of coral pests and diseases which can be detrimental to coral health. Here we review the complex relationships between corals and their associated symbiotic organisms, identify invertebrates that may harm the corals and suggest known management techniques in captivity. Groups considered included acoels (Xenacoelomorpha: Acoela), digeneans (Trematoda: Digenea), polyclads (Rhabditophora: Polycladida), gastropods (Mollusca: Gastropoda), decapods (Malacostraca: Decapoda), copepods (Hexanauplia: Copepoda) and pyrgomatids (Cirripedia: Pyrgomatidae). There are few empirically validated management techniques for coral pests, particularly in terms of large‐scale aquaculture, emphasizing the need for further directed research in this area. Information generated through the ornamental trade and hobbyists is valuable to inform future research direction targeted towards captive coral husbandry, reef ecosystem management and restoration strategies.
Aquatic parasites may respond to various attractants and cues to find and infect a host. Traps that use these attractants as ‘bait’ have potential to reduce the number of pathogenic agents in aquaculture environments. This study examined four potential attractants (i.e., urea, host mucus, parasite conspecifics and light) and the response of two problematic marine parasite species, to identify the most suitable bait for trap development in finfish aquaculture. Two globally distributed parasite species (i.e., Neobenedenia girellae, (Hargis, 1955); and Cryptocaryon irritans, Brown, 1951) were chosen as models. A chemotaxis experiment was used to compare the attractiveness of each species' infectious life stage to urea, host mucus, parasite conspecifics and a seawater control, while a phototaxis experiment was used to identify phototactic responses of the parasites to light or dark. We found that urea and light attracted more than twice the number of infective protozoans and flukes (monogeneans), respectively, compared to other attractants/controls. Cryptocaryon irritans theronts were positively chemotactic to urea (Beta Regression Analysis; Odds Ratio (OR) 2.69, p = 0.00017), while Neobendenia girellae was positively phototactic to light (Mixed Effect Logistic Regression; OR 2.5, p = 0.0014). A final experiment examined the emergence of C. irritans over a 24-hour period and identified that the vast majority excysted at night (ANOVA; p-value <0.001). In contrast, previous studies have shown that the majority of N. girellae oncomiracidia hatch in the morning. This indicated that the best time to deploy traps to capture infective C. irritans theronts and N. girellae oncomiracidia would be prior to sunset and sunrise, respectively. The manipulation of urea and light and other potential attractants combined with strategic deployment of traps to coincide with the emergence of infectious life stages may prove useful in aquaculture where parasite epidemics can compromise production and animal welfare.

Lab head

Kate S Hutson
Department
  • Aquaculture
About Kate S Hutson
  • I work as a senior scientist and am the programme lead for aquatic animal health at the Cawthron Institute in New Zealand. My research involves initiatives in disease prevention, diagnostics and treatment of farmed shellfish and fish. I especially enjoy fish health, ornamentals, biocontrols and parasitology. I previously led the Marine Parasitology Laboratory at James Cook University, Australia where I continue to supervise HDR students in my role as adjunct Associate Professor.

Members (5)

Jonathan Barton
  • Australian Institute of Marine Science
Karthiga Kumanan
  • Cawthron Institute
Katie Motson
  • James Cook University
Dylan C. Skilton
  • James Cook University

Alumni (7)

David B Vaughan
  • Central Queensland University
Truong Dinh Hoai
  • Vietnam National University of Agriculture
Thane A. Militz
  • University of the Sunshine Coast
Giana Gomes
  • Temasek Life Sciences Laboratory