Cultivation protocols the rhodophytes, Devaleraea mollis and Palmaria hecatensis from Alaska

Species diversification is crucial for the long-term viability, competitiveness, and sustainability of the seaweed farming industry in the Pacific Northwest. This study varied temperature, photoperiod, and irradiance conditions to grow Devalaraea mollis indoors and developed the first on-land cultivation protocols for Palmaria hecatensis. Both rhodophytes from Alaskahave ecotypes adapted to environmental conditions that differ from those at lower latitudes. The study also explored the use of different nutrient sources to potentially increase growth rates without compromising biomass quality or raising production costs. Results showed that specific growth rates of D. mollis and P. hecatensis significantly differed depending on the level of factors tested, indicating distinct ecological and physiological adaptations. D. mollis exhibited higher growth rates in warmer temperatures and responded to higher irradiance levels with spore release but showed no clear preference between neutral and long-day photoperiods. In contrast, P. hecatensis demonstrated higher growth rates in cooler environments with a long-day photoperiod promoting the most growth without spore release. Nutrient supplementation revealed that growth in D. mollis was affected by nutrient formulation, while P. hecatensis showed no significant growth variation. These findings underscore the importance of species- and geography-specific protocols for seaweed farming. Further research is needed to optimize the potential cultivation protocols provided here. Cultivation protocols would also benefit from exploring the ecological and physiological nuances of both species.