The Norwegian coastline covers more than 10° in latitude and provides a range in abiotic and biotic conditions for seaweed farming. In this study, we compared the effects of cultivation depth and season on the increase in biomass (frond length and biomass yield), chemical composition (protein, tissue nitrogen, intracellular nitrate and ash content) and biofouling (total cover and species composition) of cultivatedSaccharina latissimaat nine locations along a latitudinal gradient from 58 to 69° N. The effects of light and temperature on frond length and biofouling were evaluated along with their relevance for selecting optimal cultivation sites. Growth was greater at 1–2 m than at 8–9 m depth and showed large differences among locations, mainly in relation to local salinity levels. Maximum frond lengths varied between 15 and 100 cm, and maximum biomass yields between 0.2 and 14 kg m⁻². Timing of maximum frond length and biomass yield varied with latitude, peaking 5 and 8 weeks later in the northern location (69° N) than in the central (63° N) and southern (58° N) locations, respectively. The nitrogen-to-protein conversion factor (averaged across all locations and depths) was 3.8, while protein content varied from 22 to 109 mg g⁻¹DW, with seasonality and latitude having the largest effect. The onset of biofouling also followed a latitudinal pattern, with a delayed onset in northern locations and at freshwater-influenced sites. The dominant epibiont was the bryozoanMembranipora membranacea. Our results demonstrate the feasibility ofS. latissimacultivation along a wide latitudinal gradient in North Atlantic waters and underscore the importance of careful site selection for seaweed aquaculture.

The sugar kelp Saccharina latissima has received intense scientific attention over the last decades. In recent years, interest in cultivation of the species has strongly increased in the North Atlantic Ocean and the Eastern Pacific Ocean, driven by the great potential of S. latissima to be utilised for various industrial applications, including food, feed, and biomaterials. Accordingly, current research has focused on improving farming methods and technology, environmental impacts, and site selection. In addition, many studies have investigated the varying chemical composition of S. latissima, extraction of commercially interesting components, and the use of the biomass and its derived components in various applications. This review provides a comprehensive overview of farming and applications of S. latissima from the last 15 years. Additional insights on other research topics, such as ecology, physiology, biochemical and molecular biology of S. latissima, are given in the first review, “The sugar kelp Saccharina latissima I: recent advances in a changing climate” (Diehl et al. 2023).

To reach the goal of an industrialised macroalgae industry in Norway and other high-cost countries in the near future, a standardised seedling production method to improve quality control and predictability of cultivated biomass is essential. A total of 11 different treatments for seeding twine or rope with meiospores, gametophytes or juvenile sporophytes from the kelp Saccharina latissima were measured for growth (frond length, frond area, biomass yield and density) and protein content after 80 and 120 days at sea. Meiospore- and gametophyte-seeded twines were pre-cultivated in the hatchery for 14–42 days prior to deployment, while juvenile sporophytes of different ages were seeded on ropes directly on the day of deployment using a commercial binder to attach the seedlings. The results showed that seeding with meiospores pre-cultivated in the hatchery for 42 days (S42) before deployment gave significantly longer fronds (77.0 ± 6.7 cm) and a higher biomass yield (7.2 ± 0.1 kg m⁻¹) at sea compared to other treatments. The poorest growth was measured for the direct-seeded sporophytes pre-cultivated in free-floating cultures for 35 days prior to deployment (D35; 34.4 ± 2.4 cm frond length and 1.6 ± 0.4 kg m⁻¹). Image analysis was used to measure the coverage of the twine substrate before deployment, and a correlation was found between substrate coverage and frond length at sea, indicating that this can be used as a tool for quantity and quality control during the hatchery phase and before deployment. The protein content did not reveal any large differences between the treatments after 120 days of cultivation.

The aquaculture of macroalgae for human consumption and other high-end applications is experiencing unprecedented development in European countries, with the brown algae Saccharina latissima being the flag species. However, environmental conditions in open sea culture sites are often unique, which may impact the biochemical composition of cultured macroalgae. The present study compared the elemental compositions (CHNS), fatty acid profiles, and lipidomes of S. latissima originating from three distinct locations (France, Norway, and the United Kingdom). Significant differences were found in the elemental composition, with Norwegian samples displaying twice the lipid content of the others, and significantly less protein (2.6%, while French and UK samples contained 6.3% and 9.1%, respectively). The fatty acid profiles also differed considerably, with UK samples displaying a lower content of n-3 fatty acids (21.6%), resulting in a higher n-6/n-3 ratio. Regarding the lipidomic profile, samples from France were enriched in lyso lipids, while those from Norway displayed a particular signature of phosphatidylglycerol, phosphatidylinositol, and phosphatidylcholine. Samples from the UK featured higher levels of phosphatidylethanolamine and, in general, a lower content of galactolipids. These differences highlight the influence of site-specific environmental conditions in the shaping of macroalgae biochemical phenotypes and nutritional value. It is also important to highlight that differences recorded in the lipidome of S. latissima make it possible to pinpoint specific lipid species that are likely to represent origin biomarkers. This finding is relevant for future applications in the field of geographic origin traceability and food control.

The article Effect of seeding methods and hatchery periods on sea cultivation of Saccharina latissima (Phaeophyceae): a Norwegian case study, written by Si

The sugar kelp Saccharina latissima has received intense scientific attention over the last decades. In recent years, interest in cultivation of the species has strongly increased in the North Atlantic Ocean and the Eastern Pacific Ocean, driven by the great potential of S. latissima to be utilised for various industrial applications, including food, feed, and biomaterials. Accordingly, current research has focused on improving farming methods and technology, environmental impacts, and site selection. In addition, many studies have investigated the varying chemical composition of S. latissima, extraction of commercially interesting components, and the use of the biomass and its derived components in various applications. This review provides acomprehensive overview of farming and applications of S. latissima from the last 15 years. Additional insights on other research topics, such as ecology, physiology, biochemical and molecular biology of S. latissima, are given in the first review, “The sugar kelp Saccharina latissima I: recent advances in a changing climate” (Diehl et al. 2023).