Exploring the Cultivation of Ulva intestinalis in Low-Salinity Environments of the Baltic Sea

Ulva intestinalis holds promise for sustainable aquaculture in the Baltic Sea, but success has so far been limited by high environmental variability. This study examines how environmental factors influence sporogenesis, attachment, and growth of U. intestinalis in the low-salinity Baltic Sea. Optimal sporogenesis was observed at nutrient levels of 4–7 g/L, with peak zoospore release at 22–24 °C. Artificial substrates showed limited attachment success, as competing algae like Pylaiella littoralis and Cladophora glomerata often outperformed Ulva. Mesh cage cultivation demonstrated potential, achieving growth rates similar to controlled systems, though storm-induced turbidity lowered growth. These findings highlight the importance of tailored Baltic Sea cultivation strategies, focusing on nutrient, temperature, water stability, and competition management to enhance Ulva production. As the first pilot experiments in the region, they provide essential input for developing informed strategies that support more detailed trials and future scaled-up production.