Abstract
In recent years, research projects and enterprises have documented that the sugar kelp, Saccharina latissima, can be successfully cultivated in Northern European waters. There is a need however, for optimizing production methods to achieve an economically viable and competitive business. A novel direct seeding method, applying juvenile sporophytes directly onto textiles immediately before deployment, could be part of the optimization, as it obviates the nursery process, and can be combined with novel seeding materials, such as non-woven textiles. An extensive comparison of biomass yield and quality was made between direct and traditional seeding methods and substrates, including three deployment campaigns in three different cultivation sites: Textile ribbons were directly seeded with juvenile sporophytes (<1 mm size), and deployed the following day, whereas kuralone twine was traditionally seeded with spores, and deployed after a nursery period. The seeded materials were deployed in September, October and November, at Hjarnø and Limfjorden, and in November at the Grenaa site. The direct seeding method gave yields comparable to the traditional seeding method (1.0 ± 0.1 kg FW m−1 and 1.0 ± 0.2 kg FW m−1, respectively) at the most exposed site, whereas at the sheltered sites, the direct seeding method only resulted in a measurable yield following the October deployment. The highest biomass yield was achieved using the traditional seeding method, deployed in September in the Limfjorden (1.6 ± 0.4 kg FW m−1). The biomass quality was not affected by seeding method, but differed significantly between sites, with biomass from the Limfjorden having the highest content of nitrogen (4.65 ± 0.07% N of DM) and the lowest content of iodine (1.612 ± 271 mg I kg−1 of DM). In future cultivation practices, the direct seeding method could be implemented in exposed locations in Danish waters, whereas for the more sheltered/turbid waters, improvements are needed for the direct seeding technique to become feasible.
Highlights
The cultivation of kelp species holds a great potential for producing a valuable biomass supporting sustainable production of food, feed, bio energy and other applications [1,2]
An extensive comparison of biomass yield and quality was made between direct and traditional seeding methods and substrates, including three deployment campaigns in three different cultivation sites: Textile ribbons were directly seeded with juvenile sporophytes (
The new direct seeding method, where juvenile sporophytes were seeded onto non-woven substrates using a binder, is promising in the cultivation of kelps, and could potentially reduce the costs associated with additional labor and space required in the nursery phase and accelerate the upscaling and mechanization of the seaweed production industry through more efficient deployment of seeded materials [8]
Summary
The cultivation of kelp species holds a great potential for producing a valuable biomass supporting sustainable production of food, feed, bio energy and other applications [1,2]. A new direct seeding technique has been proposed, where juvenile sporophytes are adhered onto specialized non-woven textile substrates using a binder [7,8,9]. These direct techniques have the advantage of not including the resource demanding nursery phase, and could lead the way towards the use of alternative cultivation substrates such as nets, which again could optimize the stocking density and area yield, and allow quicker and more efficient deployment on site, resulting in reduced cost per unit area of farm seeded [8]. The challenges relate to the attachment of the juvenile gametophytes/spo rophytes on the cultivation substrates and fouling of the non-woven textiles used, possibly affected by local exposure and water turbidity [7,8]
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