macroalgae cultivation

The potential for growing marine biomass in Europe is great. Both natural assumptions, existing expertise and an ever-increasing need for food suggest that such a venture can be successful. However, this will require a continued active, targeted and not least coordinated effort.

In order for macroalgae such as kelp to grow, certain conditions must be met. Like other photosynthesizing plants, they need light, CO2, nitrogen, phosphorus and micronutrients such as various vitamins and minerals. In seawater, CO2 is found in dissolved form, and most macroalgae absorb CO2 in the form of HCO3 – ions. In order to succeed in kelp cultivation, one must master both the collection and release of spore plants, cultivation in the sea and harvesting of the farmed kelp. Both for the cultivation of seedlings and on-growing in sea, you need a license. Cultivation of seedlings requires temperature control, either of the air temperature of the whole unit or of the water in the cultures. The seawater must have very good quality for both small- and large-scale cultivation work; filtration, down to 0.2 – 5 μm, significantly increases water quality and is essential for large-scale production to avoid contamination. In addition, the kelp needs air supply. There are big differences when it comes to seedling production of different species, because the life cycle can be different. In any case, the most popular algae in Norway, sugar kelp and winged kelp, have quite similar life cycles.

For on-growing in sea it is important to notice that high water temperatures limit algae growth and development. Ideally, average maximum temperatures should not exceed 15° C. Minimum winter temperatures should not be so low that ice develops. Places with brackish water should be avoided, as the kelp’s productivity drastically decreases on salinity lower than 30 PSU.

Seaweed cultures require sites with suitable water exchange. Current at speeds between 5 and 10 cm s-1 is useful for growing kelp. In general, good kelp population nearby is a good indicator that the site is productive.

You can read more about macroalgae farming in the Macroalgae cultivation protocol by the Norwegian Seaweed Association