Z. marina ramets and Ulva thalli were collected from Kristineberg Marine Research Station, Fiskebäckskil, on the West
coast of Sweden in November, 2009, stored in different containers and transported to the Botany Department, Stockholm University. At the laboratory, both seagrasses and Ulva thalli were kept separately in cold (10–12 ◦C) aerated natural seawater, with fluorescent light of ca. 60 mol photon m−2 s−1, and left to acclimate for one week prior to initiation of the experiment.