Catherine M. Wilding1, Carly L. Daniels2, Jessica Knoop3, Dan A. Smale1.
1 Marine Biological Association of the UK, Citadel Hill, Plymouth, Devon, UK.
2 College of Maths Science and Engineering, University of Exeter, Penryn, Cornwall, TR10 9EZ, UK.
3 Research Group Phycology, Department of Biology, Krijgslaan 281, Sterre S8 , 9000 Ghent, Belgium
The cultivation of macroalgae is an emerging field across Europe, driven by a wide range of applications. However, commercialisation is impeded by high laboratory costs associated with traditional twine seeding. The recent development of a ‘bio-binder’ allows direct seeding onto cultivation lines followed rapidly by deployment. This can reduce production costs, bypassing the lab grow-out stage necessitated by twine seeding, but requires validation at sea.
We compared the success of twine seeding with two direct seeding methods using a Saccharina latissima gametophyte suspension applied at a standardised density of 2.45 mL m-1. Spools of twine were inoculated with meiospores and tank cultured for 7 weeks, after which twine was coiled around cultivation lines for deployment. A ‘one-stage’ direct technique involved mixing gametophytes and bio-binder solution together prior to application onto cultivation lines, while a ‘two-stage’ technique involved application of gametophytes to lines prior to coating with bio-binder. Once seeded, lines were deployed at sea as 6m long ‘droppers’ at a mixed seaweed and mussel farm in Cornwall, UK, for eight months.
Preliminary results indicate that success of direct seeding is inter-annually variable. Seeding method has a considerable effect on yield, morphology, and density of both S. latissima and non-target Saccorhiza polyschides, which settled on lines from adjacent wild populations. Further, reduced yield of S. latissima is correlated with increased abundance of S. polyschides at deeper depths, and from direct rather than twine seeding. These initial findings have the potential to progress the nascent European macroalgal cultivation industry towards commercialisation.