Spatio-temporal variability of lowland river properties and effects on metabolic rate estimates
- Author(s): VILLAMIZAR AMAYA, SANDRA ROCIO
- Advisor(s): Harmon, Thomas C.
- et al.
To determine how local features within a river reach may result in discernible transverse gradients of basic water properties and consequently of metabolic rates, we collected high-resolution spatiotemporal data across a transect spanning a lowland river cross-section. The robotically-accessed sampling points facilitated precise estimation of spatial metabolic rates for three diel cycles in April and four in September. We verified the existence of transverse spatial variability for the raw data and the derived metabolic rates, and attribute this to the combined effects of channel hydrogeomorphology and the light/shade patterns produced by the northeast to southwest orientation of the river and the riparian plant community structure along the upstream reach. Light/shade patterns observed on the reach promote gradients of available radiation and water temperature for metabolic processes, and reach hydrogeomorphology creates a transverse velocity gradient resulting in incomplete transverse mixing over timescales associated with metabolic processes. The methods and findings of this study are significant with respect to understanding spatiotemporal variation of lotic ecosystem processes at the reach scale or smaller. Such processes are potentially important in the context of ecohydrologic considerations, including designing and assessing restoration efforts, floodplain-channel dynamics, and groundwater-surface water discharges and hyporheic exchange