Seasonal effects of irradiance and pCO2 enrichment on brown alga Fucus vesiculosus in the Baltic Sea

Carbon content, nitrogen content, carbon:nitrogen ratio, chlorophyll a and chlorophyll fluorescence parameters (ETRmax, Ek, alpha, Fv/Fm) of Fucus vesiculosus were measured in two experiments (winter-summer) in the Tvärminne Zoological Station, SW Finland, Northern Baltic Sea. The algae were exposed to two irradiance treatments: 165 µmol photons/m²/s and 81 µmol photons/m²/s (winter) and 198 µmol photons/m²/s and 131 µmol photons/m²/s (summer) for high and low light treatments, respectively, with 8:16 h (winter) and 16:8 h (summer) light/dark rhythm. Irradiance was provided by Philips TL-D Super 80 58W 830 fluorescent light bulbs.