Project number: 2016-805
Project Status:
Budget expenditure: $342,200.00
Principal Investigator: Justin Seymour
Organisation: University of Technology Sydney (UTS)
Project start/end date: 30 Aug 2016 - 30 Aug 2019


During the last two decades a number of disease outbreaks have led to mass oyster mortalities and the closure of several oyster-harvesting regions, resulting in multi-million dollar losses. These outbreaks mirror a global pattern of increased aquaculture disease, with disease emergence potentially linked to environmental degradation (pollution) and climate change related processes, such as rising seawater temperature. Within NSW estuaries, multiple microbiological agents have been implicated in oyster diseases, but a clear understanding of the ecological and environmental drivers of disease outbreaks has remained elusive. This means we cannot predict when outbreaks will occur, making it very difficult to manage infection events and develop strategies to mitigate future oyster disease events.

Since 2008, Pacific Oyster fisheries in several parts of the world have been decimated by the influence of Pacific Oyster Mortality Syndrome (POMS), resulting in high (>95%) rates of juvenile oyster mortality. Recent evidence indicates that POMS is a polymicrobial syndrome, that is not only caused by the OsHV-1 virus, but includes the involvement of pathogenic bacteria from the Vibrio genus, a bacterial group comprising species that cause disease in a diverse range of marine animals and which is responsible for significant mortality in a variety of aquaculture industries. However, our understanding of this complex interaction is limited.

This project will provide valuable insights into the microbial communities associated with oysters, how those communities vary and how they might influence the course of other diseases. The project will also indicate whether breeding influences the microbial communities associated with oysters and whether this is influencing the impact diseases like OsHV is having on different Pacific oyster families.


1. Define microbial communities associated with oysters and identify threats
2. Link changes in environmental conditions to changing microbial communities
3. Better understand the association between microbial communities and disease

Final report

ISBN: 978-0-646-80891-8
Authors: Justin R. Seymour Maurizio Labbate Wayne O’Connor William King Viet Khue Nguyen Nahshon Siboni Mike Dove Cheryl Jenkins
Final Report • 2019-07-01


The principal goal of this research was to provide a detailed characterisation of the oyster microbiome and identify links between specific features of the microbiome and oyster disease and mortality events. The conceptual framework for this work is based upon: (i) increasing evidence, across a broad range of species, that the nature of a host organism’s microbiome exerts a fundamental control on host physiology and health, and (ii) the critical paucity in knowledge on the factors contributing to oyster health and the triggers for oyster mortality events and disease outbreaks. The research reported here involved a collaboration between the University of Technology Sydney (UTS) and the NSW Department of Primary Industries (DPI), whereby the UTS members of the team provided expertise in molecular microbial ecology and the DPI team members provided expertise and support in oyster physiology and ecology and aquaculture. The research involved a large-scale screening of the microbiomes of both Pacific Oysters and Sydney Rock Oysters using high-throughput DNA sequencing technologies, providing a characterisation of the microbial communities associated with oysters. The outcomes of this analysis revealed that for both Pacific Oysters and Sydney Rock Oysters, the oyster microbiome is remarkably variable among different oyster families, and over space and time, indicating that both intrinsic physiological features of the oyster host and environmental factors play a role in governing the oyster microbiome. Notably, despite this heterogeneity, a small sub-set of the microbiome was shown to be conserved across oysters within a species, pointing to the existence of a core group of microbes with intrinsic links to oyster ecology and condition. Similarly, a small group of microbes, including members of the Vibrio genus, were consistently associated with diseased or susceptible oysters, indicating a potentially antagonistic role of these microbes. These observations support the hypothesis that the oyster microbiome plays a role in defining oyster health, but also reveal substantial complexities related to the marked heterogeneity of the oyster microbiome over space and time. Appropriately considering this microbiome heterogeneity, while also sharpening focus on the few core microbiome members identified in this research, will be important requisites for
future efforts hoping to employ the oyster microbiome for diagnostic purposes. 

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Oysters Australia Ltd