Experimental design.

The diagram shows the different thermal/dark treatments (15°C dark, 15°C, 20°C, 22.5°C, 25°C and a dynamic heat stress with a peak temperature of 25°C: 25°C DHS) applied for 8 days in the gametophytes of Laminaria digitata from two populations and the subsequent recovery phase at 5°C and 15°C for 27 days. Gametophyte density and growth, development of ontogenetic stages and sporophyte recruitment parameters evaluated at different time points are also shown in the diagram.