Assessing the potential for sea-based macroalgae cultivation and its application for nutrient removal in the Baltic Sea

Abstract

<p>Marine <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/eutrophication" title="Learn more about eutrophication from ScienceDirect's AI-generated Topic Pages">eutrophication</a> is a pervasive and growing threat to global <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/environmental-impact-assessment" title="Learn more about sustainability from ScienceDirect's AI-generated Topic Pages">sustainability</a>. Macroalgal cultivation is a promising <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/circular-economy" title="Learn more about circular economy from ScienceDirect's AI-generated Topic Pages">circular economy</a> solution to achieve nutrient reduction and food security. However, the location of production hotspots is not well known. In this paper the production potential of <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/macroalgae" title="Learn more about macroalgae from ScienceDirect's AI-generated Topic Pages">macroalgae</a> of high commercial value was predicted across the Baltic Sea region. In addition, the nutrient limitation within and adjacent to macroalgal farms was investigated to suggest optimal site-specific configuration of farms. The production potential of <em>Saccharina latissima</em> was largely driven by <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/salinity" title="Learn more about salinity from ScienceDirect's AI-generated Topic Pages">salinity</a> and the highest production yields are expected in the westernmost Baltic Sea areas where salinity is >23. The direct and interactive effects of light availability, temperature, salinity and nutrient concentrations regulated the predicted changes in the production of <em>Ulva intestinalis</em> and <em>Fucus vesiculosus</em>. The western and southern Baltic Sea exhibited the highest farming potential for these species, with promising areas also in the eastern Baltic Sea. Macroalgal farming did not induce significant nutrient limitation. The expected spatial propagation of nutrient limitation caused by macroalgal farming was less than 100–250 m. Higher propagation distances were found in areas of low nutrient and low water exchange (e.g. offshore areas in the Baltic Proper) and smaller distances in areas of high nutrient and high water exchange (e.g. western Baltic Sea and Gulf of Riga). The generated maps provide the most sought-after input to support blue growth initiatives that foster the sustainable development of macroalgal cultivation and reduction of in situ nutrient loads in the Baltic Sea.<br></p>