Oyster disease in a changing environment: Decrypting the link between pathogen, microbiome and environment

Abstract

Shifting environmental conditions are known to be important triggers of oyster diseases. The mechanism(s) behind these synergistic effects (interplay between host, environment and pathogen/s) are often not clear, although there is evidence that shifts in environmental conditions can affect oyster immunity and, pathogen growth and virulence. However, the impact of shifting environmental parameters on the oyster microbiome and how this affects oyster health and susceptibility to infectious pathogens remains understudied. In this review, we summarise the major diseases afflicting oysters with a focus on the role of environmental factors that can catalyse or amplify disease outbreaks. We also consider the potential role of the oyster microbiome in buffering or augmenting oyster disease outbreaks and suggest that a deeper understanding of the oyster microbiome, its links to the environment and its effect on oyster health and disease susceptibility, is required to develop new frameworks for the prevention and management of oyster diseases.

Coupled Microbiome Analyses Highlights Relative Functional Roles of Bacteria in a Bivalve Hatchery

“…Microbial communities are known to be closely associated with aquatic species and to be important regulators and/or indicators of macrofaunal health (e.g. [1]). Shifts in marine microbiomes can forecast impending disease or death in bivalves and can thus be important biomarkers for ecosystem health (e.g., [2]).…”

Variability in the Composition of Pacific Oyster Microbiomes Across Oyster Families Exhibiting Different Levels of Susceptibility to OsHV-1 μvar Disease

“…The Pacific oyster, Crassostrea gigas is a globally cultivated oyster species, but the cultivation of this species has been increasingly impacted by disease events (Azéma et al, 2015). These disease events are largely caused by viral and bacterial etiological agents (Friedman et al, 2005; Garnier et al, 2007; Segarra et al, 2010; King et al, 2019), but in some instances no clear etiological agent is identifiable (Go et al, 2017; King et al, 2018). A major pathogen of C. gigas is the ostreid herpesvirus 1 (OsHV-1), and its micro variant form (OsHV-1 μvar) (Davison et al, 2005; Segarra et al, 2010).…”

A New High Throughput Sequencing Assay for Characterizing the Diversity of Natural Vibrio Communities and Its Application to a Pacific Oyster Mortality Event

“…One of the many areas where the development of a high precision assay for determining Vibrio community diversity would have great utility is within the aquaculture industry, where Vibrio infections cause substantial losses in stock and profits (Gay et al, 2004;Lafferty et al, 2015;Lemire et al, 2015;Bruto et al, 2017;Green et al, 2019), but the precise identity of the pathogen is often not well resolved or incorrectly assigned to the wrong species (Sawabe et al, 2013;Richards et al, 2014;Dubert et al, 2017;Green et al, 2019). Some Vibrio species, including Vibrio splendidus and Vibrio coralliilyticus, have negative impacts on oyster cultivation by causing mortality in hatcheries (Sugumar et al, 1998;Takahashi et al, 2000;Elston et al, 2008;Richards et al, 2015;King et al, 2019a). Outside of hatchery settings, a number of Vibrio species have been identified as oyster pathogens (Waechter et al, 2002;Saulnier et al, 2010;Duperthuy et al, 2011;Wendling et al, 2014;Bruto et al, 2017;Go et al, 2017;King et al, 2019a).…”

“…Some Vibrio species, including Vibrio splendidus and Vibrio coralliilyticus, have negative impacts on oyster cultivation by causing mortality in hatcheries (Sugumar et al, 1998;Takahashi et al, 2000;Elston et al, 2008;Richards et al, 2015;King et al, 2019a). Outside of hatchery settings, a number of Vibrio species have been identified as oyster pathogens (Waechter et al, 2002;Saulnier et al, 2010;Duperthuy et al, 2011;Wendling et al, 2014;Bruto et al, 2017;Go et al, 2017;King et al, 2019a). Because of the complexity of oyster diseases, direct evidence for the involvement of Vibrio species often remains unproven; therefore, they are usually regarded as opportunistic pathogens (Garnier et al, 2007;Jenkins et al, 2013;Go et al, 2017;De Lorgeril et al, 2018).…”