Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; BIOACID; Biological Impacts of Ocean Acidification; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chlorophyll a; Chromista; Coast and continental shelf; Dry mass; Fresh weight, complete; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); German Bight, North Sea; Germination rate; Growth/Morphology; Growth rate; Helgoland; Identification; Incubation duration; Inhibition of net photosynthesis; Irradiance; Irradiance, standard deviation; Laboratory experiment; Laminaria hyperborea; Life stage; Light:Dark cycle; Macroalgae; Maximal electron transport rate, relative; Maximum photochemical quantum yield of photosystem II; Meeresstation Helgoland; MULT; Multiple investigations; Net photosynthesis rate, oxygen; Net photosynthesis rate, oxygen, per chlorophyll a; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; off_Helgoland; Oogonium formation rate; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Phlorotannins; Potentiometric; Potentiometric titration; Primary production/Photosynthesis; Replicate; Reproduction; Salinity; Single species; Species; Temperate; Temperature, water; Temperature, water, standard deviation; Treatment