Advancing Best Practice Harvest and Storage of Tropical Rock Oysters: Temperature-Driven Microbial Dynamics

The cultivation of tropical Blacklip Rock Oysters (BROs) (Saccostrea spathulata) supports a developing Indigenous-led enterprise in remote regions of northern Australia, but little is known about how post-harvest storage temperature influences shelf-life and associated microbial dynamics in this tropical species. We assessed the shelf-life of BROs at 4 degrees C, 13 degrees C, 18 degrees C and 25 degrees C to evaluate compliance with industry sensory and microbiological standards. In parallel, we used high-throughput DNA sequencing to characterise shifts in the microbial community associated with post-harvest storage. Across all storage conditions, oysters met current industry benchmarks for food safety and quality. However, microbial community composition shifted significantly with storage time and temperature. Spoilage at high storage temperatures (18 degrees C and 25 degrees C) was accompanied by the proliferation of Malaciobacter spp., Roseimarinus spp., Vibrio diabolicus, and V. mediterranei, while longer storage at lower temperatures (4 degrees C and 13 degrees C) favoured the growth of Pseudoalteromonas spp. and V. kanaloae. These findings demonstrate that spoilage dynamics are strongly temperature-dependent and reveal microbial taxa that act as more informative indicators of post-harvest deterioration than current industry tests. This study demonstrated that storage at 4 degrees C provided the greatest microbial stability and is thus recommended as the optimal storage temperature for the BRO industry. Collectively, this work offers an enhanced framework for advancing spoilage surveillance in tropical oyster production and storage.