Dark acclimation of Lithophyllum kotschyanum and Porolithon sp. Photochemical quantum yield in the light (white background) and in the dark (grey shading) of the topside (black circles) and underside (open circles) of L. kotschyanum thalli and the upper surface of Porolithon sp. crusts (black triangles). Darkness occurred at 14:50, thus the measurement at 15 minutes represents 10 second of 'quasi' dark-acclimation. Data presented as mean ± SD.