Seawater carbonate chemistry, N/C and P/C biomass ratios, Polyunsaturated fatty acids of Rhodomonas sp. and Phaeodactylum tricornutum

• Main Authors: Bi, Rong, Ismar, Stefanie M, Sommer, Ulrich, Zhao, Meixun
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; partial pressure; Chromista; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Laboratory strains; Macro-nutrients; Nitrogen/Carbon ratio; Nitrogen/Phosphorus ratio; Nitrogen cellular quota; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phaeodactylum tricornutum; Phosphorus/Carbon ratio; Phytoplankton; Polyunsaturated fatty acids; Ratio; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.883475; https://doi.org/10.1594/PANGAEA.883475

Marine phytoplankton is simultaneously affected by multiple environmental drivers. To-date integrative assessments of multiple combined effects are rare on the relationship between elemental stoichiometry and biochemicals in marine phytoplankton. We investigated responses of stoichiometric (N:C and P:C ratios) and fatty acid-based (polyunsaturated fatty acid, PUFA) indicators of nutritional quality to three N:P supply ratios (10:1, 24:1, and 63:1 mol/mol), three temperatures (12, 18, and 24°C) and two pCO2 levels (560 and 2400 µatm) in the marine phytoplankters Rhodomonas sp. and Phaeodactylum tricornutum. Overall, warming and nutrient deficiency showed dramatic effects, but increased pCO2 had modest effects on the two indicators of nutritional quality. Specifically, warming showed strong positive effects on N:C and P:C ratios in Rhodomonas sp. but negative effects on PUFAs in both species. The low N- and low P-media led to low contents of both nutrients but high contents of PUFAs in the biomass of Rhodomonas sp., while the response of P. tricornutum was more complex: N:C ratios were lowest at the intermediate N:P supply but P:C ratios responded negatively to P deficiency and positively to N deficiency. Large variations in the two indicators of nutritional quality can be attributed to species-specific physiological optima and interactions between the three manipulated variables. Our results suggest that stoichiometric and FA-based indicators of nutritional quality may change differentially in response to warming and nutrient deficiency in marine phytoplankton, highlighting the relevance of simultaneous considerations of the two indicators of nutritional quality, when assessing food web dynamics under future ocean scenarios.