Land-based aquaculture offers several advantages for seaweed cultivation, such as precise control of growing conditions and circumventing the need for boats, but to expand the land-based seaweed industry, there is a need for more affordable and scalable production of seed stock. Gametophyte banking of kelp has been shown as a key technique to improve consistency and product quality for ocean-based farms. Our goal for this study was to combine these techniques and develop a protocol for kelp gametophyte seeding in land-based systems, from the nursery phase to a grow out phase in tumble culture.
Gametophyte cultures of Alaria marginata were used to inoculate ceramic tiles nested within centrally lit nurseries suitable for micro- and macroalgae, referred to as CLASH (Core Lit Apparatus for Seaweed Hatcheries). We tested the effects of tile depth, relative position, and two application methods on tile cover (% total area) and blade length at harvest (mm), then transferred the kelp seedlings into secondary tumble cultures to monitor survival. Harvest data were obtained from 36 tiles distributed across three replicate tanks after an eight-week trial, and we fit a linear mixed-effects model to account for the hierarchical structure.
After eight weeks in nursery, tile cover and blade length were 89.01 ± 9.96 % and 5.32 ± 3.98 mm respectively (mean ± SD, Figure 1). There were no significant effects of depth, position, or application method on tile cover or length (p > 0.05), and kelp blades persisted for three weeks in tumble culture before ending all trials. Our findings show the potential of using gametophyte cultures in combination with fully land-based aquaculture methods. Additional studies seek to optimize culturing conditions within our nursery system to improve yields when seeding with gametophytes, as well as scaling up use of CLASH for commercial production in tumble culture.