Seawater carbonate chemistry and growth of Prochlorococcus and Synechococcus strains

• Main Authors: Knight, Margaret A, Morris, J Jeffrey
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2020
• Subjects: Bacteria; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria <20 L; Cyanobacteria; Growth/Morphology; Laboratory experiment; Laboratory strains; Not applicable; Pelagos; Phytoplankton; Prochlorococcus sp.; Species interaction; Synechococcus sp.; Type; Figure; Experiment; Species; Strain; Identification; Treatment; Replicates; Comment; Time in days; Cell density; Growth rate; Frequency; Fitness; Salinity; Temperature, water; Alkalinity, total; pH; pH, standard deviation; Partial pressure of carbon dioxide water at sea surface temperature wet air; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Fugacity of carbon dioxide water at sea surface temperature wet air; Fugacity of carbon dioxide in seawater, standard deviation; Partial pressure of carbon dioxide, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Calcite saturation state; Calcite saturation state, standard deviation; Potentiometric titration; Potentiometric; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. 2010; Calculated using seacarb after Orr et al. 2018; Ocean Acidification International Coordination Centre OA-ICC; Ocean acidification
• Online Access: https://dx.doi.org/10.1594/pangaea.930555; https://doi.pangaea.de/10.1594/PANGAEA.930555

Anthropogenic CO2 emissions are projected to lower the pH of the ocean 0.3 units by 2100. Previous studies suggested that Prochlorococcus and Synechococcus, the numerically dominant phytoplankton in the oceans, have different responses to elevated CO2 that may result in a dramatic shift in their relative abundances in future oceans. Here we showed that the exponential growth rates of these two genera respond to future CO2 conditions in a manner similar to other cyanobacteria, but Prochlorococcus strains had significantly lower realized growth rates under elevated CO2 regimes due to poor survival after exposure to fresh culture media. Despite this, a Synechococcus strain was unable to outcompete a Prochlorococcus strain in co‐culture at elevated CO2. Under these conditions, Prochlorococcus' poor response to elevated CO2 disappeared, and Prochlorococcus' relative fitness showed negative frequency dependence, with both competitors having significant fitness advantages when initially rare. These experiments suggested that the two strains should be able to co‐exist indefinitely in co‐culture despite sharing nearly identical nutritional requirements. We speculate that negative frequency dependence exists due to reductive Black Queen evolution that has resulted in a passively mutualistic relationship analogous to that connecting Prochlorococcus with the “helper” heterotrophic microbes in its environment. : In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2021) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2021-04-19.