FIGURE 4.

The effects of CO₂ and/or temperature on the abundance (g^-1 sediment) of (A) bacterial 16S rRNA, (B) archaeal 16S rRNA, and (C) bacterial nirS genes in the bottom layer (0.5–2.5 cm) of muddy sediment. Four syringe cores were taken at each time point (T0, light gray; T7, dark gray; and T28, black) from each environmental treatment (x-axis). Significant effects from the model output are indicated by the letter a (where there is an interaction with day); b (interaction between elevated CO₂ and elevated temperature). Error bars represent standard deviation of repeated measurements (n = 4) from treatment replicates (n = 3).