Figure 1.
Fatty acid composition and concentration of Thalassiorira pseudonana cultured at different CO2 treatments.
A) Percentage of polyunsaturated (PUFA), monounsaturated (MUFA), and saturated (SFA) fatty acids relative to total fatty acids during the exponential growth phase cultured at low (realized value of 365 µatm pCO2, n = 5) and high (realized value of 915 µatm pCO2, n = 3) CO2 treatments used as copepod food source. B) Change in the fatty acid composition in T. pseudonana after a shift from high to low pCO2 conditions (n = 1 per treatment level). Time 0 are measured values before the culture media shift. Error bars indicate standard errors.
Figure 2.
Fatty acid composition, somatic growth and reproduction of Acartia tonsa across CO2 treatment combinations.
A) Percentage of polyunsaturated (PUFA), monounsaturated (MUFA), and saturated (SFA) fatty acids relative to total fatty acids in female copepods. B) Principal component analysis (PCA) of fatty acid composition for the dietary algae Thalassiorira pseudonana and A. tonsa of the different treatment combinations. PCA scores 1 explained 40% of the variability (see x-axis of c) and was highly negatively correlated with 22:6n-3 (r2 = 0.73), 20:4n-6+20:5n-3 (r2 = 0.85), 18:3n-6 (r2 = 0.73) and 16:1 (r2 = 0.79), and positively with 22:1n-9 (r2 = 0.25) and 18:1n-9t (r2 = 0.57). PCA score 2 explained 17% of the overall variability (see y-axis of c) and was strongest positively correlated with 24:0 (r2 = 0.84). Loadings of the PC scores are shown in Figure S2). C) Stage distribution of A. tonsa individuals at day 10. C4, C5, C6 = copepodite stage 4, 5, and adult, respectively. D) Egg production rate (EPR) of incubated females (n = 12 per treatment level). EPR was significantly different between treatments (F(3, 44) = 18.02, p<0.001). Different letters above bars represent significant differences from a Tukey HSD test. The bars represent the 25th, 50th and 75th percentiles, whiskers stand for the 10th and the 90th percentiles and black points show outliers. Legend refers to treatment combinations of copepod zooplankton (Z) and phytoplankton food source (P) at low (L) and high (H) pCO2.
Table 1.
Regression statistics of Acartia tonsa egg production as a linear function of fatty acid composition.