@article{article_1850193, title={A preliminary study on the effects of seagrass wrack extract as biofertilizer on the growth, ice-ice disease, nitrogen, and phosphorus assimilation and carrageenan quality of eucheumatoid seaweed Kappaphycus striatus}, journal={Aquatic Research}, volume={9}, pages={166–175}, year={2026}, DOI={10.3153/AR26014}, url={https://izlik.org/JA84TT29CD}, author={Tahiluddin, Albaris and Terzi, Ertuğrul}, keywords={Biofertilizer, Carrageenan, Eucheumatoid seaweed farming, Kappaphycus, Seagrass wrack}, abstract={<p>Eucheumatoid seaweed farming is a significant aquaculture activity, not only supplying carrageenan to the global market but also serving as a vital livelihood source for many marginalised coastal communities, particularly in Tawi-Tawi, Philippines. However, the practice of applying chemical fertilisers in eucheumatoid seaweed farming to boost production by enhancing growth performance and mitigating ice-ice disease has become a contentious issue among local stakeholders in this region. This preliminary, proof-of-concept study investigated the potential of utilising seagrass wrack (Thalassia hemprichii) as a biofertilizer alternative, evaluating its effects on growth, ice-ice disease prevalence and intensity, nitrogen and phosphorus assimilation, and carrageenan quality (yield and gel strength) in the eucheumatoid seaweed Kappaphycus striatus. The experiment employed various concentrations of seagrass wrack extract (SWE): 0 mL L⁻¹ (control), 9 mL L⁻¹, 18 mL L⁻¹, and 27 mL L⁻¹. The results revealed no significant effects of SWE on growth or ice-ice disease prevalence and intensity (number and length of ice-ice spots per bundle) after 15, 30, and 45 days of cultivation. Nitrogen and phosphorus assimilation did not significantly impact SWE. Additionally, no impact on gel strength was observed after 45 days. Interestingly, a significant difference was detected in carrageenan yield, with the 27 mL L⁻¹ SWE treatment exhibiting a notably higher yield compared to all other treatments at the 45-day mark. While this study demonstrates the potential of SWE to enhance carrageenan yield, its lack of significant effects on K. striatus growth and health raises concerns about its overall suitability as a biofertilizer. Therefore, further research is warranted to explore the potential optimisation of the seagrass wrack extract, investigate the use of alternative seagrass wrack species or combinations, and identify strategies to improve the overall effectiveness of SWE as a biofertilizer. </p>}, number={2}, organization={This research received external funding from the Southeast Asian Regional Center for Graduate Study and Research in Agriculture (SEARCA) PhD Research Scholarship.}