Figure 4

Xanthophyll cycle pigment ratios (average ± standard deviation; n = 5) in Vaucheria litorea and Elysia chlorotica in response to different light conditions: (i) “Dark”, dark-adapted samples for 60 min before the start of chlorophyll (Chl) fluorescence measurements; (ii) “HL”, high-light stress correspondent to exposure to 1800 μmol photons m⁻² s⁻¹ for 15 min; and (iii) “Recovery”, exposure to dark conditions during 30 min following the HL stress.

(a) Dt/(Dt + Dd) ratios (content of diatoxanthin [Dt] relative to the total pool of pigments of the xanthophyll cycle Dt + diadinoxanthin [Dd]). (b) Total pool of pigments of the xanthophyll cycle per Chl a. * indicates significant differences (P < 0.05) between light treatments (Dark, HL and Recovery).