No abstract

Macroalgae-based products are increasing in demand also in Europe. In the European Union, each category of macroalgae-based products is regulated separately. We discuss EU legislation, including the law on medicinal products, foods including food supplements and food additives, feed and feed additives, cosmetics, packaging materials, fertilizers and biostimulants, as well as biofuels. Product safety and consumer protection are the priorities with any new products. Macroalgae products can be sold as traditional herbal medicines. The novel food regulation applies to macroalgae foods that have not previously been used as food, and organic macroalgae are a specific regulatory category. The maximum levels of heavy metals may be a barrier for macroalgae foods, feeds, and fertilizers. Getting health claims approved for foods based on macroalgae is demanding. In addition to the rules on products, the macroalgae business is strongly impacted by the elements of the general regulatory environment such as agricultural/aquacultural subsidies, maritime spatial planning and aquaculture licensing, public procurement criteria, tax schemes, and trade agreements.

In parts of the Baltic Sea, the phytoplankton spring bloom communities, commonly dominated by diatoms, are shifting toward the co-occurrence of diatoms and dinoflagellates. Although phytoplankton are known to shape the composition and function of associated bacterioplankton communities, the potential bacterial responses to such a decrease of diatoms are unknown. Here we explored the changes in bacterial communities and heterotrophic production during the spring bloom in four consecutive spring blooms across several sub-basins of the Baltic Sea and related them to changes in environmental variables and in phytoplankton community structure. The taxonomic structure of bacterioplankton assemblages was partially explained by salinity and temperature but also linked to the phytoplankton community. Higher carbon biomass of the diatoms Achnanthes taeniata, Skeletonema marinoi, Thalassiosira levanderi, and Chaetoceros spp. was associated with more diverse bacterial communities dominated by copiotrophic bacteria (Flavobacteriia, Gammaproteobacteria, and Betaproteobacteria) and higher bacterial production. During dinoflagellate dominance, bacterial production was low and bacterial communities were dominated by Alphaproteobacteria, mainly SAR11. Our results suggest that increases in dinoflagellate abundance during the spring bloom will largely affect the structuring and functioning of the associated bacterial communities. This could decrease pelagic remineralization of organic matter and possibly affect the bacterial grazers communities.

Plankton communities and their temporal development have shifted towards earlier onset of the spring bloom and lower diatom-dinoflagellate proportions in parts of the Baltic Sea. We studied the effects of community composition and spring bloom phases on seston nutrient stoichiometry, revealing possible consequences of these shifts. Community composition, seston C:N:P:Si:chl a ratios, and physiological and environmental variables were determined for 4 research cruises, covering all major sub-basins and bloom phases. A redundancy analysis revealed that temperature and inorganic nutrients were the main drivers of community changes, and high diatom biomass was linked to low temperatures (growth phase). The effects of changing dominance patterns on seston stoichiometry were studied by applying a community ordination (non-metric multidimensional scaling and generalized additive models). C:N:P ratios increased from the growth phase (103:14:1) to the peak phase (144:18:1) and decreased after inorganic nitrogen was depleted (127:17:1). Taxonomic differences explained ~50% of changes in C:Si, N:Si, and chl a:C ratios and <30% for C:P and N:P, whereas C:N was virtually unaffected by the community composition. The fixed chl a:C range (~0.005-0.04) was largely determined by diatoms, independent of the dominant species. Thus, C:Si and N:Si could be used to estimate the share of diatoms to the seston and chl a:C to describe bloom phases and C budgets during spring. Interestingly, mixed communities featured higher C:N:P ratios than diatom-dominated ones. However, as community composition explained <30% of changes in C:N:P, we conclude that these ratios rather represent the total plankton physiology in natural plankton assemblages.