New hatchery methods for efficient spore use and seedling production of Palmaria palmata (dulse)

Abstract

Palmaria palmata (dulse) is a high valued rhodophyte; nevertheless, its hatchery methods are underdeveloped. New hatchery methods are required to improve the spore use efficiency and seeding quality, which are important benchmarks for a viable cultivation. This study investigated a method using vertical seeding tanks (exp. 1), hemispherical agitation and flow-through conditions to improve spore dispersal on net substrates. Tanks were inoculated with different amounts of sori tissue, which sporulated in three consecutive seeding periods. The results demonstrated significant effect of seeding period where 5–15 g FW sori could be used to seed three nets (~ 126 m rope) over the course of 9 days providing a density up to 10 seedlings cm−1 after 32 days. The effluent spores were collected in detaining tanks and germinated into a propagule mix of female and male gametophytes. The propagule mix was efficient as a secondary seeding inoculum, as propagules were able to reattach to substrates up to 39 days after their release as spores (exp. 2). Adding male gametes to the propagule mix and spore seeded ropes was tested as a relevant hatchery step to activate female gametophytes and significantly resulted in more than a doubling of seedlings (exp. 3). This study present new methods and strategies to improve spore use efficiency and to obtain an equal spore dispersal on net substrates for hatchery production of P. palmata.