Effects of different seedstrings on the nursery of Pyropia yezoensis

Seedstring cultivation is a fundamental method for Pyropia yezoensis aquaculture, as it provides an artificial substrate for the attachment of P. yezoensis spores and growth of gametophytes. This method has been widely used in the P. yezoensis aquaculture all over the world because of its convenience for seaweed management and harvest. However, the composition and types of seedstrings vary in different countries. Little is known about the effect of different seedstrings in terms of spore attachment and early development of gametophytes in P. yezoensis. In this study, four types of commercially available seedstrings from Korea (KR), China (CN), and Japan (JP1 and 2) and three new seedstring types developed by W.L. Gore & Associates, Inc. (Gore A, B, and C) were compared in terms of seeding density, growth rate, and biomass yield. Our results show that the Gore C seedstring had the highest seeding density and yield among all seedstrings. The Gore B had the lowest seeding density and yield. The Gore A and B seedstrings had the highest growth rate at early stages in development. The CN and KR seedstring showed lower growth rates than the other seedstring types. A comprehensive evaluation shows that the Gore C seedstring type had the best performance among all seven seedstrings under laboratory conditions. Future studies are needed to test the performance of the seedstrings on Pyropia farms.