Examples of shores and tide levels surveyed in the present study. A - Mindelo, in northern Portugal, B - Santa Cruz, in central Portugal and, C - Dona Ana, in southern Portugal. D - High intertidal at Monte Clérigo, with Melarhaphe neritoides, E - Mid-intertidal at Arrifana, with barnacles and mussels, F - Low intertidal at Mindelo featuring Himanthalia elongata, which is now almost extinct from the area. Photos taken by Fernando P. Lima.