Boosting Seaweed Growth with a Two-Kelp Strategy

Jenn Hoskins
3rd July, 2024

Boosting Seaweed Growth with a Two-Kelp Strategy

The co-culture system used in the study leverages the opposing buoyancy of Bull kelp (Nereocystis luetkeana) (N) and Sugar kelp (Saccharina latissima) (S) to create vertical separation, enabling a more efficient use of the water column to increase total biomass yield per unit area.

Adapted from: Stekoll et al. (Photo by David Bailey) / CC BY (Source)

Key Findings

  • The study took place in Kodiak, Alaska, where researchers grew two kelp species together to optimize biomass yield
  • Combining Saccharina latissima and Nereocystis luetkeana in a single farming system produced the highest total yields
  • Despite having 45% fewer grow-lines, the yield of Nereocystis in the combined arrays was similar to that in the Nereocystis-only arrays
Interest in farming kelps has expanded beyond traditional uses like food, feed, or biofuels. There is growing interest in using seaweed biomass for bioplastics and other products that could replace petroleum-derived materials. For these applications to be economically viable, large quantities of biomass are needed. Building and maintaining large kelp farms can be costly, which necessitates optimizing biomass yield per unit area. A promising approach involves growing two species of kelps together: one that grows downwards and another that is buoyant and grows upwards. This method increases the spacing in three dimensions, potentially enhancing overall yield. A recent study conducted by the University of Alaska Fairbanks explored this innovative approach by growing Saccharina latissima and Nereocystis luetkeana together in a longline array in Kodiak, Alaska[1]. Saccharina latissima, commonly known as sugar kelp, typically grows hanging down from longlines. In contrast, Nereocystis luetkeana, a buoyant kelp, grows upwards. The researchers set up closely spaced lines seeded in early February 2023, placing them 3 meters below the surface. The arrays were harvested in late June 2023. The study found that the combined arrays, which included both Saccharina and Nereocystis, produced the highest total yields. Interestingly, despite having 45% fewer grow-lines, the yield of Nereocystis in the combined arrays was statistically similar to that in the Nereocystis-only arrays. These results suggest that integrating different kelp species in a single farming system can optimize space and increase biomass production, which is crucial for large-scale macroalgal production. This study builds on previous research that highlights the environmental benefits and scalability of kelp farming. For instance, a Life Cycle Assessment (LCA) of a 400-hectare Chinese kelp farm showed that large-scale kelp cultivation could achieve lower energy consumption and a smaller carbon footprint compared to smaller farms[2]. The Chinese farm, which harvested 60,000 tons of kelp annually, demonstrated that mature, large-scale production is more efficient in terms of electricity and fuel use. Furthermore, breeding programs have also aimed to improve kelp yields. A multi-year study by the U.S. Department of Energy's ARPA-E MARINER program focused on breeding Saccharina latissima to meet the growing demands of the mariculture industry[3]. The program found that crosses between sugar kelp and skinny kelp species resulted in higher yields and longer blades, suggesting that selective breeding can enhance kelp production. The University of Alaska Fairbanks study ties these findings together by demonstrating that combining different kelp species in a single farming system can further optimize biomass yield. This approach could complement large-scale, efficient farming practices observed in Chinese kelp farms[2] and benefit from the improved yields achieved through selective breeding programs[3]. Overall, the study provides valuable insights into optimizing kelp farming for large-scale production, making it a promising solution for generating biomass for bioplastics and other sustainable products.

SustainabilityPlant ScienceMarine Biology

References

Main Study

1) Optimizing seaweed biomass production - a two kelp solution

Published 2nd July, 2024

https://doi.org/10.1007/s10811-024-03296-w

Related Studies

2) Life Cycle Assessment of a large commercial kelp farm in Shandong, China.

https://doi.org/10.1016/j.scitotenv.2023.166861

3) Skinny kelp (Saccharina angustissima) provides valuable genetics for the biomass improvement of farmed sugar kelp (Saccharina latissima).

https://doi.org/10.1007/s10811-022-02811-1


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