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Aquaculture Environment Interactions

    AEI prepress abstract   -  DOI:

    The effect of air exposure, handling stress and imidacloprid on the susceptibility of Crassostrea gigas to ostreid herpesvirus 1 (OsHV-1)

    Rebecca Oliver, Marine Fuhrmann, Paul Hick*

    *Corresponding author:

    ABSTRACT: The emergence of the microvariants genotype of ostreid herpesvirus 1 (OsHV-1 µVar) has caused mass mortalities of Pacific oysters Crassostrea gigas, resulting in significant economic losses in Europe, New Zealand and Australia. There is variability in the occurrence and severity of disease caused by OsHV-1, with the disease incompletely described by the known complex interactions between host, environment and pathogen. There is a need to evaluate the role of the anthropogenic factors on this disease expression due to the number of interactions between humans and oysters. A controlled in vivo laboratory infection model was used to assess changes to the susceptibility of 6 mo old Pacific oysters to OsHV-1 challenge after pre-exposure to combinations of stressors. Oysters pre-exposed to a concentration of the pesticide imidacloprid which is consistent with the higher range of environmental contamination in some estuaries had no impact on the survival or OsHV-1 viral load for the oysters. Oysters pre-exposed to air for 24 h prior to OsHV-1 challenge by cohabitation were more resilient to infection. Moderate physical handling that simulated on-farm handling did not affect survival. This indicates that farm management practices implemented prior to OsHV-1 exposure might not specifically predispose oysters to more severe disease, and more complex confounding factors need to be considered. It is likely that changes in host physiology during emersion provide the host with increased resilience to disease caused by OsHV-1. Continued investigation of the effect of air exposure in the field will aid in validating the results from this laboratory experiment.