Twine selection is essential for successful hatchery cultivation of Saccharina latissima, seeded with either meiospores or juvenile sporophytes

Abstract

The predominant method used for the cultivation of European kelp involves seeding onto twine spools. The selection of a suitable twine is essential. In four experiments, synthetic and natural polymer twines were seeded with either meiospore or juvenile sporophytes of Saccharina latissima. Development was monitored over both the hatchery and outplanting phase at an experiment seaweed farm, Scotland, UK. Twisted twine seeded with meiospores gave 37 ± 21% higher biomass yield than the braided form, despite 46 ± 10% lower sporophyte density during the hatchery period. Twisted twine was also more favourable when sporophyte seeding, increasing juvenile retention by 140%. Three-month-old sporophytes had 50% weaker bioadhesion on polyamide (PA), polyester (PES) and polypropylene (PP) compared to polyvinyl alcohol (PVA). This was reflected in 11-24% higher biomass on PVA following outplanting. However, if the twine surface was treated by corona discharge before seeding, PA, PES and PP achieved an equivalent biomass to PVA. Jute and sisal twine had a toxic effect on the development of meiospores. In contrast, seeding with sporophytes was successful onto jute and sisal, but bioadhesion was weak. Finally, cotton was moderately toxic to meiospores but also had a bioadhesion strength and biomass yield comparable to PVA. We conclude that PVA and corona-treated synthetic twines are excellent for either meiospore or sporophyte seeding. Cotton is a very promising biodegradable twine, although further research is needed to optimise its physical structure. We also conclude that results during the hatchery period do not predict the success of seeded twine following outplanting.

Effect of seeding methods and hatchery periods on sea cultivation of Saccharina latissima (Phaeophyceae): a Norwegian case study

“…The rope structure and material used for seeding have proven to have a large impact on the harvesting yield. Twisted ropes have shown significantly better performance than braided ropes for both spore and juvenile sporophyte seeding (Kerrison et al 2019). The spores and gametophytes were seeded on a twisted nylon string (⌀ 1.2 mm and wound around ⌀ 18 mm twisted rope when deployed), while the treatments using a binder were seeded directly on a braided rope (⌀ 18 mm, AlgaeRope).…”

“…This method can be advantageous as the use of incubation facilities might be shortened by several weeks or, in the case of direct seeding, omitted completely. The use of a binder to attach spores, gametophytes or sporophytes to the substrate is preferred by several commercial farmers and in research projects (Mols-Mortensen et al 2017;Bak et al 2018;Kerrison et al 2018Kerrison et al , 2019. Recent experiments have shown that a binder method of cultivation is not only as effective as traditional methods but also can be 100 times more space-efficient during the laboratory phase (Kerrison et al 2018).…”

Comparing the effectiveness of twine- and binder-seeding in the Laminariales species Alaria esculenta and Saccharina latissima

“…Their firm initial attachment allows the sporophytes to immediately tolerate high wave energy. The physical and chemical characters of the twine dictate how strongly the juveniles are attached, and so can influence the final yield (Kerrison et al 2019b ). As the sporophytes mature, their developing holdfasts spread onto the carrier rope and will mechanically interlock around the rope and neighbouring holdfasts (pers.…”

The SeaCoRe system for large scale kelp aquaculture: a plug-and-play, compatible, open-source system for the propagation and transport of clonal gametophyte cultures

“…To this day, there is no clear consensus on which cultivation method is best suited for large-scale kelp aquaculture. Kelp aquaculture is still being practiced using two fundamentally different cultivation methods (Kerrison et al 2019;Goecke et al 2020), which are categorized here as the controlled-and uncontrolled reproductive methods (Ebbing et al 2021). The uncontrolled reproductive method (URM) is characterized by releasing substantial amounts of zoospores in large tanks that are filled with twine rope.…”