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The European seaweed sector transitions from harvesting wild stocks only to harvesting and farming seaweed. This transition comes with the need to rethink the role of the European sector on the global scale; insight is needed into the organization of, and innovation in, the global seaweed value chain. This article presents results from our study on value chains using Gereffi’s conceptual framework. A systematic review of scientific publications published between 2010 and 2020 was executed for five markets: pharmaceuticals, bioplastics, biostimulants, alginate and cosmetics. It is concluded that innovation in the use of seaweed takes place across the globe and thus that a focus on high-value applications alone will not set the nascent European seaweed sector apart from established producing regions such as Asia. The studied global value chains are organised around strong lead firms that require suppliers to produce according to codified product characteristics. The European seaweed sector needs to increase the collaboration and develop joint efforts to develop safe and sustainable products that meet the demands of regulators, lead firms and consumers. Stronger coordination in the value chain will facilitate further business development, by stimulating collaboration and innovations.

The Australian redclaw crayfish Cherax quadricarinatus is a freshwater crustacean aquacultured in many countries. Redclaw crayfish are often exposed to saline waters in attempts to improve flavor, to relieve stress during transport, and to prevent or treat parasitic infestations. However, the effect of salinity on the crayfish osmoregulatory process is not well studied. In the present work, we assessed the effect of various salinities on survival, growth, and osmoregulation in redclaw crayfish. Adult crayfish were maintained at seven salinities (0, 2, 4, 6, 8, 10, and 12 ppt) for 4 weeks, and hemolymph osmolality, gill sodium potassium ATPase activity, and sodium potassium chloride cotransporter expression were assessed. In another experiment, juvenile crayfish were size sorted to similar weights and stocked at four salinities (0, 2, 4, and 6 ppt) for 8 weeks. The animals were group weighed every 2 weeks and individually weighed at the end of the eighth week. Hemolymph osmolality was constant as salinity increased from 0 to 10 ppt then a significant increase was observed at 12 ppt. Redclaw growth rate decreased with an increase in salinity from 0 to 6 ppt. Sodium potassium ATPase activity and sodium potassium chloride cotransporter expression increased with salinity increase. Although salinity might help treat ectoparasites, improve taste, and reduce transportation stress, long-term exposure increases osmoregulatory metabolic costs and affects growth and energy consumption.

Phlorotannins, C-based defence compounds in brown seaweeds, show a high degree of spatial and temporal vari-ation within seaweed species. One important model explaining this variation is the Carbon Nutrient Balance Model (CNBM), which states that the relative supply of carbon and limiting nutrients will determine the level of defence compounds in plants. Nitrogen is often considered to be the limiting nutrient for marine macroalgal growth and the CNBM thus predicts that when the carbon:nitrogen ratio is high, photosynthetically fixed carbon will be allocated to production of phlorotannins. In the present study, we evaluated the effects of light (i.e. carbon) and nitrogen on the phlorotannin content of two intertidal brown seaweeds, Ascophyllum nodosum and Fucus vesiculosus. This was done in an observational field study, as well as in a manipulative experiment where plants from habitats with different light regimes were subjected to different nitrogen and light treatments, and their phlorotannin content was measured after 14 days. The results showed that there was a negative relationship between tissue nitrogen and phlorotannin content in natural populations of F. vesiculosus, but not in A. nodosum. In the short term, the phlorotannin content in both algal species was not affected by changes in nitrogen availability. Exposure to sunlight had a positive effect on the phlorotannin content in natural populations of both algal species but, in the manipulative experiment, only F. vesiculosus showed a rapid response to changes in light intensities. Plants subjected to sunlight contained higher phlorotannin content than shaded plants. In conclusion, the results imply that nitrogen availability explains some of the natural variation in the phlorotannin content of F. vesiculosus, but the light environment has greater importance than nitrogen availability in predicting the phlorotannin content of each species.