Seawater carbonate chemistry and respiratory metabolism of microplankton

• Main Authors: Tames-Espinosa, Mayte, Martinez, I, Romero-Kutzner, Vanesa, Coca, Josep, Algueró-Muñiz, Maria, Horn, Henriette G, Ludwig, Andrea, Taucher, Jan, Bach, Lennart Thomas, Riebesell, Ulf, Packard, Ted T, Gómez, May
• Format: Dataset
• Language: English
• Published: PANGAEA 2020
• Subjects: Alkalinity; total; Amoeba; Amphidinium; Aragonite saturation state; Bicarbonate ion; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chlorophyll a; Ciliates; Coast and continental shelf; Community composition and diversity; DATE/TIME; Day of experiment; Dinophyceae; Diplopsalis group indeterminata; Entire community; Event label; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gymnodinium; Katodinium glaucum; KOSMOS_2014; KOSMOS_2014_Atlantic-Reference; KOSMOS_2014_Mesocosm-M1; KOSMOS_2014_Mesocosm-M2; KOSMOS_2014_Mesocosm-M3; KOSMOS_2014_Mesocosm-M4; KOSMOS_2014_Mesocosm-M5; KOSMOS_2014_Mesocosm-M6; KOSMOS_2014_Mesocosm-M7; KOSMOS_2014_Mesocosm-M8; KOSMOS_2014_Mesocosm-M9; Macro-nutrients; MESO; Mesocosm experiment; Mesocosm label; Mesocosm or benthocosm; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Oxytoxum; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.925263; https://doi.org/10.1594/PANGAEA.925263

In the autumn of 2014, nine large mesocosms were deployed in the oligotrophic subtropical North-Atlantic coastal waters off Gran Canaria (Spain). Their deployment was designed to address the acidification effects of CO2 levels from 400 to 1,400 μatm, on a plankton community experiencing upwelling of nutrient-rich deep water. Among other parameters, chlorophyll a (chl-a), potential respiration (PHi), and biomass in terms of particulate protein (B) were measured in the microplankton community (0.7–50.0 μm) during an oligotrophic phase (Phase I), a phytoplankton-bloom phase (Phase II), and a post-bloom phase (Phase III). Here, we explore the use of the PHi/chl-a ratio in monitoring shifts in the microplankton community composition and its metabolism. PHi/chl-a values below 2.5 μL O2/h/ (μg chl-a) indicated a community dominated by photoautotrophs. When PHi/chl-a ranged higher, between 2.5 and 7.0 μL O2/h/ (μg chl-a), it indicated a mixed community of phytoplankton, microzooplankton and heterotrophic prokaryotes. When PHi/chl-a rose above 7.0 μL O2/h/ (μg chl-a), it indicated a community where microzooplankton proliferated (>10.0 μL O2/h/ (μg chl-a)), because heterotrophic dinoflagellates bloomed. The first derivative of B, as a function of time (dB/dt), indicates the rate of protein build-up when positive and the rate of protein loss, when negative. It revealed that the maximum increase in particulate protein (biomass) occurred between 1 and 2 days before the chl-a peak. A day after this peak, the trough revealed the maximum net biomass loss. This analysis did not detect significant changes in particulate protein, neither in Phase I nor in Phase III. Integral analysis of PHi, chl-a and B, over the duration of each phase, for each mesocosm, reflected a positive relationship between PHi and pCO2 during Phase II [alpha = 230*10−5 μL O2/h/L/(μatm CO2)/(phase-day), R2 = 0.30] and between chl-a and pCO2 during Phase III [alpha= 100*10−5 μg chl-a/L/ (μ atmCO2)/ (phase-day), R2 = 0.84]. At the end of Phase II, a harmful ...