Bacteriomes associated with white‐leg disease in tropical rock lobster ( Panulirus ornatus ) hatcheries

Abstract

White‐leg disease (WLD) is an emerging condition affecting tropical rock lobster, Panulirus ornatus, larviculture, characterized by whitening of pereiopods and uropods, followed by rapid mortality. Despite its significant impact on aquaculture productivity, the bacterial drivers and environmental sources of WLD are still poorly understood. This study characterizes the bacteriomes associated with P. ornatus larvae and their culture environment across two hatcheries: Ornatas Pty Ltd. in Townsville, Queensland (a commercial hatchery), and the Institute for Marine and Antarctic Studies (IMAS) in Hobart, Tasmania (a research hatchery) to identify bacterial composition and potential sources of pathogens. Using Oxford Nanopore 16s rRNA gene sequencing, we profiled bacterial communities from healthy and diseased phyllosoma, as well as environmental compartments including water, biofilm, fresh and aged feed: Feed 6 h old and feed 20 h old. Diseased larvae across both hatcheries showed distinct bacterial shifts, with elevated relative abundance of Aquimarina spp. and Vibrio spp. taxa detected by Nanopore 16S sequencing. Notably, these taxa were also detected in the rearing environment, particularly in fresh feed and biofilm, which suggests possible transmission pathways. The detection of overlapping bacterial communities between larvae and their environment supports the hypothesis that environmental parameters play a critical role in WLD onset and progression. These findings provide new insights into the bacterial ecology of WLD, identifying potential causative agents and their environmental sources. Moreover, this study highlights the importance of integrated microbiome surveillance across the rearing system and informs the future development of microbiome‐based health monitoring and disease mitigation strategies in P. ornatus hatcheries.