River primary production and metabolism

Ecosystem ecology encompasses the interactions between biotic (community attributes) and abiotic components of a system. Ecosystem studies focus on defining and exploring functional processes, including nutrient cycling, decomposition, and primary productivity, or the amount of carbon fixed in an ecosystem. In aquatic ecosystems, gross primary productivity (GPP) and respiration (R) can be measured using diel changes in dissolved oxygen concentration. Net ecosystem productivity (NEP), or the net carbon fixed, is calculated by subtracting respiration from gross primary productivity. (NEP = GPP – R).

A principal ecosystem project in our lab is investigating the effects of hydrogeomorphology on NEP in sand bed rivers. Changes in hydrology alter the geomorphic structure of the river, creating diverse habitats within the river, including backwaters, side channels, and point bars. Current studies are comparing NEP in both lateral and longitudinal habitats.