Simulated marine heatwaves promote greater post-harvest Vibrio parahaemolyticus abundances in Pacific oysters (Crassostrea gigas) but not Sydney rock oysters (Saccostrea glomerata)
Elliot Scanes, Nachshon Siboni, Amaranta Focardi, Justin R. SeymourContext
Climate change is increasing the frequency of marine heatwaves (MHW), raising concerns about foodborne illness linked to marine pathogens such as Vibrio parahaemolyticus.
Aims
To determine whether simulated MHW conditions promote accumulation of V. parahaemolyticus in oysters and influence post-harvest pathogen loads.
Methods
Two commercial oyster species – Pacific oysters (Crassostrea gigas) and Sydney rock oysters (Saccostrea glomerata) – were exposed to a clinical V. parahaemolyticus strain under ambient (22°C) and elevated (24–28°C) temperatures for 9 days. Oysters were then held in dry storage for 5 days. Abundances of V. parahaemolyticus in seawater and gill tissue were quantified using quantitative PCR (tlh gene).
Key results
Pacific oysters accumulated six-fold higher V. parahaemolyticus levels than Sydney rock oysters after 2 days. Contrary to expectations, elevated temperature did not increase pathogen levels during seawater exposure. However, Pacific oysters previously exposed to heatwave conditions showed significantly higher post-harvest pathogen abundance.
Conclusions
MHW do not immediately elevate V. parahaemolyticus in oyster tissues but can amplify post-harvest pathogen loads, particularly in Pacific oysters.
Implications
Heatwave exposure may elevate seafood safety risks post-harvest, highlighting the need for targeted management strategies and species-specific risk assessment in warming coastal environments.