Metabolic synchrony in stream networks

Synchrony of dissolved oxygen (DO) signals among river network elements reflects the dynamic balance between shared regional drivers, signal propagation, and local hydraulic, energetic, and metabolic heterogeneity. We used high frequency DO measurements at 42 sites across five watersheds catchments to evaluate DO signal synchrony among reaches in response to dynamic variation in light availability and discharge. We hypothesized that homogeneity of light availability and longitudinal hydrologic connectivity between sites would enhance synchrony in DO signals. We observed strong support that increasing spatial homogeneity of light inputs, both in magnitude and diel variation, greatly increase diel DO signal synchrony both within and across stream networks during early spring and fall. We further observed the central role of longitudinal connectivity in controlling within network synchrony. Specifically, shared regional drivers (light, temperature) increase the synchrony in DO signals when flow connectivity was high, whereas fine-scale patch behavior and low synchrony, especially in smaller streams, occurred when connectivity declines. A model including light synchrony and longitudinal connectivity explained 65% of variation in dynamic DO synchrony. We provide a framework for evaluating DO signal synchrony at confluences with implications for broadly understanding solute where network flow elements mix. DO synchrony and network and confluence scales provides an empirical demonstration of the dynamic balance between regional drivers and local patch dynamics modulated by the flow-varying length scales of signal integration.