Light availability and temperature, not increased CO2, will structure future meadows of Posidonia oceanica

• Main Authors: Hendriks, Iris, Olsen, Ylva, Duarte, Carlos Manuel
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; Aragonite saturation state; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; partial pressure; Coast and continental shelf; Dry mass; Experiment; Experiment duration; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Identification; Irradiance; Laboratory experiment; Leaf; growth rate; standard error; Leaf area; Leaf area index; Light; Light saturation point; Maximal electron transport rate; relative; Maximum photochemical quantum yield of photosystem II; Mediterranean Sea; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Photosynthetic quantum efficiency; Plantae; Posidonia oceanica; Potentiometric; Potentiometric titration; Primary production/Photosynthesis; Range; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.875001; https://doi.org/10.1594/PANGAEA.875001

We evaluated the photosynthetic performance of Posidonia oceanica during short-term laboratory exposures to ambient and elevated temperatures (24-25 °C and 29-30 °C) warming and pCO2 (380, 750 and 1000 ppm pCO2) under normal and low light conditions (200 and 40 µmol photons/m**2/s respectively). Plant growth was measured at the low light regime and showed a negative response to warming. Light was a critical factor for photosynthetic performance, although we found no evidence of compensation of photosynthetic quantum efficiency in high light. Relative Electron Rate Transport (rETRmax) was higher in plants incubated in high light, but not affected by pCO2 or temperature. The saturation irradiance (Ik) was negatively affected by temperature. We conclude that elevated CO2 does not enhance photosynthetic activity and growth, in the short term for P. oceanica, while temperature has a direct negative effect on growth. Low light availability also negatively affected photosynthetic performance during the short experimental period examined here. Therefore increasing concentrations of CO2 may not compensate for predicted future conditions of warmer water and higher turbidity for seagrass meadows.