Publication Date:
2024-05-27
Description:
Sea ice retreat, changing stratification, and ocean acidification are fundamentally changing the light availability and physico-chemical conditions for primary producers in the Arctic Ocean. However, detailed studies on ecophysiological strategies and performance of key species in the pelagic and ice-associated habitat remain scarce. Therefore, we investigated the acclimated responses of the diatoms Thalassiosira hyalina and Melosira arctica toward elevated irradiance and CO2 partial pressures (pCO2). Next to growth, elemental composition, and biomass production, we assessed detailed photophysiological responses through fluorometry and gas-flux measurements, including respiration and carbon acquisition. In the pelagic T. hyalina, growth rates remained high in all treatments and biomass production increased strongly with light. Even under low irradiances cells maintained a high-light acclimated state, allowing them to opportunistically utilize high irradiances by means of a highly plastic photosynthetic machinery and carbon uptake. The ice-associated M. arctica proved to be less plastic and more specialized on low-light. Its acclimation to high irradiances was characterized by minimizing photon harvest and photosynthetic efficiency, which led to lowered growth. Comparably low growth rates and strong silification advocate a strategy of persistence rather than of fast proliferation, which is also in line with the observed formation of resting stages under low-light conditions. In both species, responses to elevated pCO2 were comparably minor. Although both diatom species persisted under the applied conditions, their competitive abilities and strategies differ strongly. With the anticipated extension of Arctic pelagic habitats, flexible high-light specialists like T. hyalina seem to face a brighter future.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Antenna size; Aragonite saturation state; Arctic; Bicarbonate ion; Biogenic silica, per cell; Biogenic silica/Carbon, organic, particulate; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, particulate, per cell; Carbon, organic, particulate, production per cell; Carbon/Nitrogen ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Central_Arctic_ocean; Chlorophyll a/particulate organic carbon ratio; Chlorophyll a per cell; Chromista; Connectivity between photosystem II; Electron transport rate, relative; Electron transport rate, relative, maximum velocity; Event label; EXP; Experiment; Fluorometry; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gas-flux measurement; Growth/Morphology; Growth rate; Identification; Irradiance; KongsfjordenOA; Laboratory experiment; Light; Light saturation point; Maximum light use efficiency; Maximum photochemical quantum yield of photosystem II; Melosira arctica; Net photosynthesis rate, carbon dioxide, per chlorophyll a; Net photosynthesis rate, oxygen, per chlorophyll a; Net photosynthesis rate, oxygen, per particulate organic carbon; Non photochemical quenching; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Open ocean; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate organic carbon production, per chlorophyll a; Particulate organic carbon production, per particulate organic carbon; Pelagos; Percentage; pH; pH, standard deviation; Photosynthetic efficiency, carbon production; Photosynthetic quotient; Phytoplankton; Polar; Primary production/Photosynthesis; Ratio; Reopening rate; Respiration; Respiration rate, oxygen, per chlorophyll a; Salinity; Single species; Species, unique identification; Species, unique identification (Semantic URI); Species, unique identification (URI); Temperature, water; Temperature, water, standard deviation; Thalassiosira hyalina; Treatment: partial pressure of carbon dioxide; Type
Type:
Dataset
Format:
text/tab-separated-values, 4737 data points
