Transplant methods
All transplant sites were located in 4 – 5 m depth in area of open dead-matte, surrounded by P. oceanica meadow. In Mallorca and Cyprus, fragments were distributed between two sites, separated by approximately 1 km. In Catalunya, lack of suitable dead matte habitat meant that all fragments were placed in one site. Fragments were planted along parallel transects at 50 cm intervals and with a 50 cm gap between parallel transects (Fig. S1). Different treatments were mixed and deployed haphazardly along each transect.