Calcium alginate as a biocompatible encapsulation agent: Material characterization and physiological effects in Gracilaria dura

The transportation of seaweed propagules (vegetative) materials is a major bottleneck in aquaculture due to high mortality, reduced viability, and deterioration of biochemical and physiological traits during prolonged transportation. Calcium alginate, a biocompatible encapsulation agent, was evaluated for preparing seaweed propagules using Gracilaria dura . This innovation represents a significant advance in seaweed biotechnology, offering, new material, improved process, and transformative applications. The study assessed alginate encapsulation as a propagule preparation strategy utilizing bio-effector treatment (0.25 mg L −1 BAP for 60 min, followed by 1 g L −1 AMPEP for 60 min and 0.25 mg L −1 kinetin for 30 min). Alginate beads showed 81–86% transparency, good rheological stability, and higher gel strength in non-immersed beads (410 g cm −2 ) compared to seawater-immersed beads (354 g cm −2 ). Encapsulation reduced chlorophyll a (24.9 µg g −1 FW), phycocyanin (22.5 µg g −1 FW), and phycoerythrin (55.76 µg g −1 FW) content. Treated beads showed higher total antioxidant capacity (422.94 µg g −1 ) than untreated biomass (326.40 µg g −1 ). Peak NPP and GPP occurred in April (0.113 ± 0.010 and 0.120 ± 0.008 mg C L −1 h −1 , respectively), with lower respiration in treated encapsulated thalli. HPLC revealed high hormones, while negligible pathogens confirmed material safety. The pathogenic bacterial load (CFU/g) was evaluated to determine and address the biosecurity aspects. Thus, encapsulation of propagules in calcium alginate beads combined with bio-effector treatment significantly improved physiological performance, antioxidant activity, and microbial safety that could aid its use for potential transportation application of seaweed propagules.