Palmaria palmata (Dulse) cultivation in Denmark – new strategies for hatchery optimization

Interest in Palmaria palmata for human consumption has increased in Europe lately, indicated by high market prices reaching 245 € per dry kg. As demands go up, focus on cultivation rather than wild harvest is important to avoid diminishment of wild populations and to secure a sustainable production.

However, low spore-to-seedling efficiency, imposing a high requirement of sori for seeding in large-scale cultivation, points to a need for developing current hatchery techniques. In a step-wise approach focusing on spore release, spore seeding, and seedling development, we have developed new protocols to optimize cultivation practice for P. palmata.

In a line of setups, we have investigated the effect of parameters, such as substrate type and water agitation, on the spore release rate, the spore settlement and the seedling development. Also, in a new approach using released spore aggregates as inoculum, we have tested the ability of these to re-attach using high agitation seeding as an alternative to the normally used gravity-based seeding method.

Finally, a first attempts to seed on nets in a high-agitated flow-through system has been carried out. The level of water agitation had a strong positive effect on the settlement and dispersal of spores and seedlings in general, with a further implication for the ability of macerated spore aggregates to re-attach.

Aggregates germinating into a mixture of spores and sporelings during 30 days showed an ability of discoid re-attachment and growth after maceration pretreatment, and applying high water agitation resulted in 39% survival of seedlings which is to be considered high for this species. Based on this study, we suggest new versatile strategies for P. palmata cultivation including the use of germinated spore aggregates showing the ability of discoid re-attachment on twine, and high-agitated seeding systems for improved spore use and spore dispersal on cultivation lines