Seawater carbonate chemistry and phytoplankton growth and mortality

• Main Authors: Ragazzola, Federica, Marchini, Agnese, Adani, Mario, Bordone, Andrea, Castelli, Alberto, Cerrati, Gabriella, Kolzenburg, Regina, Langeneck, Joachim, di Marzo, Carlotta, Nannini, Matteo, Raiteri, Giancarlo, Romanelli, Elisa, Santos, Mar, Vasapollo, Claudio, Pipitone, Carlo, Lombardi, Chiara
• Format: Dataset
• Language: English
• Published: PANGAEA 2021
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Benthos; Bicarbonate ion; Calcification/Dissolution; Calcification rate; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Containers and aquaria (20-1000 L or < 1 m**2); Electric potential; potential difference; electromotive force; Ellisolandia elongata; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Macroalgae; Mediterranean Sea; Net calcification rate of calcium carbonate; dark; light; Net photosynthesis rate; oxygen; Nitrate; Nitrogen dioxide; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.939993; https://doi.org/10.1594/PANGAEA.939993

In coastal marine ecosystems coralline algae often create biogenic reefs. These calcareous algal reefs affect their associated invertebrate communities via diurnal oscillations in photosynthesis, respiration and calcification processes. Little is known about how these biogenic reefs function and how they will be affected by climate change. We investigated the winter response of a Mediterranean intertidal biogenic reef, Ellisolandia elongate exposed in the laboratory to reduced pH conditions (i.e. ambient pH – 0.3, RCP 8.5) together with an extreme heatwave event (+1.4°C for 15 days). Response variables considered both the algal physiology (calcification and photosynthetic rates) and community structure of the associated invertebrates (at taxonomic and functional level). The combination of a reduced pH with a heatwave event caused Ellisolandia elongata to significantly increase photosynthetic activity. The high variability of calcification that occurred during simulated night time conditions, indicates that there is not a simple, linear relationship between these two and may indicate that it will resilient to future conditions of climate change. In contrast, the associated fauna were particularly negatively affected by the heatwave event, which impoverished the communities as opportunistic taxa became dominant. Local increases in oxygen and pH driven by the algae can buffer the microhabitat in the algal fronds, thus favouring the survival of small invertebrates.