Seawater carbonate chemistry and biomass and fatty acid composition of a post-bloom marine plankton community

• Main Authors: Dörner, Isabel, Hauss, Helena, Aberle, Nicole, Lohbeck, Kai T, Spisla, Carsten, Riebesell, Ulf, Ismar, Stefanie M
• Format: Dataset
• Language: English
• Published: PANGAEA 2020
• Subjects: Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; 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; Community composition and diversity; DATE/TIME; Date/time end; Day of experiment; Entire community; Event label; Fatty acids; Fatty acids of water; Field experiment; Fjord; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); KOSMOS_2015; KOSMOS_2015_Mesocosm-M1; KOSMOS_2015_Mesocosm-M2; KOSMOS_2015_Mesocosm-M3; KOSMOS_2015_Mesocosm-M4; KOSMOS_2015_Mesocosm-M5; KOSMOS_2015_Mesocosm-M6; KOSMOS_2015_Mesocosm-M7; KOSMOS_2015_Mesocosm-M8; KOSMOS_2015_Mesocosm-M9; KOSMOS Bergen; MESO; Mesocosm experiment; Mesocosm or benthocosm; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phase (mineralogy/biology); Phosphate; Phytoplankton; biomass; Salinity; Norway; Bergen; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.929270; https://doi.org/10.1594/PANGAEA.929270

A mesocosm approach was used to investigate the effects of ocean acidification (OA) on a natural plankton community in coastal waters off Norway by manipulating CO2 partial pressure ( pCO2). Eight enclosures were deployed in the Raunefjord near Bergen. Treatment levels were ambient (320 µatm) and elevated pCO2 (~2000 µatm), each in 4 replicate enclosures. The experiment lasted for 53 d in May-June 2015. To assess impacts of OA on the plankton community, phytoplankton and protozooplankton biomass and total seston fatty acid content were analyzed. In both treatments, the plankton community was dominated by the dinoflagellate Ceratium longipes. In the elevated pCO2 treatment, however, biomass of this species as well as that of other dinoflagellates was strongly negatively affected. At the end of the experiment, total dinoflagellate biomass was 4-fold higher in the control group than under elevated pCO2 conditions. In a size comparison of C. longipes, cell size in the high pCO2 treatment was significantly larger. The ratio of polyunsaturated fatty acids to saturated fatty acids of seston decreased at high pCO2. In particular, the concentration of docosahexaenoic acid (C 22:6n3c), essential for development and reproduction of metazoans, was less than half at high pCO2 compared to ambient pCO2. Thus, elevated pCO2 led to a deterioration in the quality and quantity of food in a natural plankton community, with potential consequences for the transfer of matter and energy to higher trophic levels.