Multiple stressors including eutrophication, sediment runoff, dredging and coastal development have been suggested as drivers of this negative development. Although bladder wrack is now recovering in some areas (Kautsky, Martin, & Snoeijs-Leijonmalm, 2017, Laamanen, Korpinen, Zweifel, & Andersen, 2017), it is still declining at other locations (Vahteri & Vuorinen, 2016). During the last years, the depth distribution has increased, for instance at the Swedish coast of the northern Baltic proper and the Sea of Aland. Eutrophication is suggested to be the main driver for the historical decrease in bladder wrack (Torn et al.,