Seaweed farming is the fastest-growing aquaculture industry in the U.S . Bull K elp (Nereocystis luetkeana), valued for its commercial, cultural, and ecological significance in the Pacific Northwest, has drawn considerable interest. Cal Poly Humboldt established a one-acre seaweed farm in Humboldt Bay, CA. This study aimed to 1) assess twine efficiency in nursery cultivation of B ull K elp sporophytes, 2) evaluate growth at varying depths on the farm using different cultivation systems, and 3) analyze heavy metal and nutrient profiles of harvested biomass for human consumption safety.
The nursery consisted of eight 24-L tanks held in a flow-through recirculating system. Each tank incubated five 10-inch spools wrapped in different twine types, including Hemp (Hem) 1mm, Kuremono Kuraraay vinolyn (Kur) 1mm, Korean- polypropylene (PP)/ polyethylene (PE) (Kor) 1.5mm, Gortex-polyester/fluoropolymer (Gor), and Powers-Nylon 1.2mm (Nyl). Sporophytes were nursed for six months, and the quality was assessed based on % coverage, blade coloration, blade consistency, and unwanted growth.
Preliminary analyses using Shapiro -Wilk and Levene’s tests revealed non-normal data distribution and heterogeneous variances. The Kruskal-Wallis test confirmed significant variations in spool quality among different twine types. Dunn’s post-hoc test highlighted Kur as superior (p = 0.02 ; Kur vs Gortex ) and 0.03 (Kur vs Korean
). One-w ay ANOVA and Tukey HSD post-hoc test confirmed spool quality variations across twine types (Fig . 2, 3)
.
Results from this study contributed to a comprehensive understanding of Bull Kelp cultivation on long lines in California.