A multi-unit (minimum 8 units), ideally rack-mounted photo-bioreactor (PBR) system for closed, biosecure cultivation of macroalgae gametophytes and sporophytes propagated by fragmentation, with capacity to also support microalgae culture. Each unit must provide independent closed-loop control of temperature, pH, and LED light spectrum/intensity, enabling parallel climate-stress treatments (e.g., simulated heatwave vs. ambient baseline) on the same rack footprint, alongside biosecure fragmentation, low-shear circulation, and fine-particle filtration to prevent contamination. A centralized controller must allow monitoring and logging across all units while preserving independent control per unit. The system will support climate-impact research on harvested seaweed species, including thermal performance and stress-response trials.