Abstract
Asparagopsis armata has international commercial relevance due to its high bromoform content, which can reduce the methane emissions from cattle when incorporated into their diet. However, few studies have reported on at‐sea cultivation techniques and their effect on bromoform content in A. armata. In this study, we assessed the effects of seeding density (150, 300 and 600 g WW m −1 ) on the specific growth rate (SGR) and bromoform content of A. armata in suspended culture on a marine farm. We also tested whether transport conditions affected bromoform content, comparing emersed and immersed A. armata biomass after 3.5 h. Seeding density had a strong effect on the SGR of A. armata with the lowest seeding density having significantly greater growth (1.5 to 5 times) than higher seeding densities. Transporting the A. armata biomass in seawater increased its bromoform content (by 73.6%) relative to the immersed material. These findings will inform efficient approaches to the sea‐based culture of A. armata .