2.3 Allometric scaling relationships
Prior to calculating allometric scaling relationships, we calculated cumulative values for respiration and HEFs as the sum of all reaches upstream of a given reach (and inclusive of the reach), as visualized for a watershed in Figure S2. We calculated allometric scaling relationships as cumulative hyporheic aerobic respiration (g CO2 d-1) against watershed area (km2) following Wollheim et al. (2022). First, we grouped reaches in each basin into 10 equally sized quantiles based on cumulative HEF, which is an important control of hyporheic respiration (Son et al. 2022). Within each quantile, a random subset of 50 reaches representing the range of stream orders was selected via bootstrapping and used to calculate slope, intercept, and R2 values for the relationship between cumulative respiration and watershed area. This process was then iterated 1000 times for each combination of bin and basin to calculate average values and confidence intervals for slope, intercept, and R2 values.