Managing zoosporic infections in microalgae production systems: ecology, detection, risk factors, and biosecurity strategies

Zoosporic parasites represent a pervasive and structurally embedded biosecurity challenge in large-scale microalgae cultivation systems. These fungal and fungal-like organisms, characterised by motile zoospores, combine active host localisation, rapid intracellular development, and long-term persistence through resistant resting stages. Under the high-density, monoculture conditions typical of industrial production, such life-history traits facilitate rapid transmission, nonlinear outbreak dynamics, and recurrent culture collapse. Despite their demonstrated impact on productivity, economic performance, and operational continuity, zoosporic parasites remain insufficiently integrated into routine monitoring frameworks and risk management strategies, with control practices still largely reactive.