Measured diurnal curves of dissolved oxygen (DO) concentration have been used to estimate the gross primary production (GPP), ecosystem respiration (R), and net ecosystem production (NP) of aquatic communities. Open-system one-station and two-station methods have been employed to estimate the rate of NP, R, and GPP. We conducted field measurements in Minnehaha Creek, MN (44o56'N, 93o28'W), to quantify the spatial and temporal variabilities of DO concentrations and, consequently, evaluated the estimates of NP. Dimensionless analysis of DO mass balance revealed the dominance of local photosynthesis over respiration, advection, re-aeration, and dispersion along the studied reach. Two alternative estimation methods of stream metabolism provided similar estimates of NP with 0.65>kaTa>0.17 within the studied reach where ka is the re-aeration rate and Ta is the water parcel average travel time. The spatial variability of DO change along the creek revealed an average length scale of 10m over which DO exhibited significant autocorrelation. The autotrophic-heterotrophic balance, quantified by GPP to R ratio, scaled with local stream geomorphic and hydraulic conditions from diverse geographic areas, providing useful predictive relationships expressed in terms of easily measurable abiotic parameters.
- Fluid mechanics
- Gross primary production