Bacterial disease in seaweed aquaculture: pathogen diversity and future solutions

In recent years, there has been a rapid expansion in seaweed aquaculture due to the increased demand for sustainable food, pharmaceuticals, and other industrial needs. This growth has been accompanied by a rise in disease prevalence, jeopardising the economic viability of seaweed farming and the livelihoods of millions reliant on the sector. Here, through focusing on the complex interactions between seaweed hosts and their microbial communities, we review current knowledge on bacterial seaweed pathogens. We discuss the challenges associated with pathogen identification, including the constraints of traditional approaches and the complexities arising from resident commensal bacteria. We then assess the use of probiotics, selective breeding, Integrated Multi-Trophic Aquaculture (IMTA), site selection, and the priming of early life stages as emerging disease management strategies, while highlighting the need for omics-based studies to identify disease biomarkers and commercially relevant disease-resistant strains. We conclude by underlining the importance of early detection systems and improved knowledge dissemination within the sector to enable a more proactive and sustainable approach to disease management.