Different photosynthetic responses of haploid and diploid Emiliania huxleyi (Prymnesiophyceae) to high light and ultraviolet radiation

Abstract Solar radiation varies quantitatively and qualitatively while penetrating through the seawater column thus is one of most important environmental factors shaping vertical distribution pattern phytoplankton. The haploid diploid life-cycle phases coccolithophores might have different preferences. Therefore, two respond differently to high solar photosynthetically active (PAR, 400–700 nm) ultraviolet (UVR, 280–400 nm). To test this, Emiliania huxleyi were exposed oversaturating irradiance. In presence PAR alone, effective quantum yield was reduced by 10% more due higher damage rate photosystem II in cells than cells. addition UVR resulted further inhibition for both first 25 min, partly because increased II. Intriguingly, this UVR-induced completely recovered half an hour later. This recovery confirmed comparable maximum yields, relative electron transport rates yields treated with + UVR. Our data indicated that photosynthesis phase sensitive visible light but resistant inhibition, reflecting ecological niches which species adapts. Graphical