Publication Date:
2024-03-15
Description:
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 algal species (HAS), Vicicitus globosus, bloomed in the high pCO2 mesocosms. In these mesocosms, microzooplankton did not proliferate, and chl-a retention time in the water column increased. In these V. globosus-disrupted communities, the PHi/chl-a ratio [4.1 +- 1.5 μL O2/h/(μg chl-a)] was more similar to the PHi/chl-a ratio in a mixed plankton community than to a photoautotroph-dominated one.
Keywords:
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; pH; Pronoctiluca sp.; Proteins, particulate; Protoperidinium sp.; Respiration; Respiration rate, oxygen, potential; Salinity; Scuticociliates, fractionated; Subtropical North Atlantic; Temperate; Temperature, water; Tintinnida indeterminata; Torodinium sp.; Type
Type:
Dataset
Format:
text/tab-separated-values, 6763 data points
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