Seawater carbonate chemistry and coccolithophore abundances and CaCO3 concentrations during the 2013 MedSeA mesocosm experiment

• Main Authors: D'Amario, Barbara, Pérez-Mejías, Carlos, Grelaud, Michaël, Paraskevi, Pitta, Krasakopoulou, Evangelia, Ziveri, Patrizia
• Format: Dataset
• Language: English
• Published: PANGAEA 2020
• Subjects: Alkalinity; total; Ammonia; Aragonite saturation state; Bicarbonate ion; Calcification/Dissolution; Calcite saturation state; Calcium carbonate; particulate; Calculated; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell density; Coast and continental shelf; Coccospheres; malformed; Community composition and diversity; Conductivity sensor; Aanderaa; type 3919; Counted; Crete-mesocosms; DATE/TIME; Day of experiment; Entire community; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Laboratory experiment; Mass; Measured and/or detected by SYRACO software; Mediterranean Sea; MESO; Mesocosm experiment; Mesocosm or benthocosm; Nitrate; Nitrite; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; Pendant Temperature/Light Data Logger 64K; HOBO; pH; Phosphate; Potentiometric; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.931628; https://doi.org/10.1594/PANGAEA.931628

Mesocosm experiments have been fundamental to investigate the effects of elevated CO2 and ocean acidification (OA) on planktic communities. However, few of these experiments have been conducted using naturally nutrient-limited waters and/or considering the combined effects of OA and ocean warming (OW). Coccolithophores are a group of calcifying phytoplankton that can reach high abundances in the Mediterranean Sea, and whose responses to OA are modulated by temperature and nutrients. We present the results of the first land-based mesocosm experiment testing the effects of combined OA and OW on an oligotrophic Eastern Mediterranean coccolithophore community. Coccolithophore cell abundance drastically decreased under OW and combined OA and OW (greenhouse, GH) conditions. Emiliania huxleyi calcite mass decreased consistently only in the GH treatment; moreover, anomalous calcifications (i.e. coccolith malformations) were particularly common in the perturbed treatments, especially under OA. Overall, these data suggest that the projected increase in sea surface temperatures, including marine heatwaves, will cause rapid changes in Eastern Mediterranean coccolithophore communities, and that these effects will be exacerbated by OA.