Interaction of nutrient enrichment and farming method on performance of the red seaweed Kappaphycus alvarezii

To meet the increasing demand for kappa carrageenan, several strategies have been employed to improve eucheumatoid seaweed productivity, such as nutrient enrichment (NE) and the application of some efficient farming methods (FM). This study aims to investigate the interaction of NE (applied as ammonium phosphate at 3.5 g L⁻¹) and farming method on the performance of the eucheumatoid seaweed Kappaphycus alvarezii. Three farming methods, that is, Sway (SW), Spring (SP), and modified fixed-off bottom (MFOB), were employed for nutrient-enriched (NE) and non-enriched control fronds for a period of 45 days. NE significantly improved the growth and carrageenan yield of the seaweed and afforded protection against the incidence of ice-ice disease; meanwhile, the effect of FM and NE-FM interaction was non-significant. NE increased the gel strength of the extracted carrageenan; meanwhile, SP farm led to the highest gel strength, followed by MFOB.