Metabolism Regimes in Regulated Rivers of the Illinois River Basin, USA

Abstract

Metabolism estimates organic carbon accumulation by primary productivity and removal by respiration. In rivers it is relevant to assessing trophic status and threats to river health such as hypoxia as well as greenhouse gas fluxes. We estimated metabolism in 17 rivers of the Illinois River basin (IRB) for a total of 15,176 days, or an average of 2.5 years per site. Daily estimates of gross primary productivity (GPP), ecosystem respiration (ER), net ecosystem productivity (NEP), and the air-water gas exchange rate constant (K600) are reported, along with ancillary data such as river temperature and saturated dissolved oxygen concentration, barometric pressure, and river depth and discharge. Workflows for metabolism estimation and quality assurance are described including a new method for estimating river depth. IRB rivers are dominantly heterotrophic; however, autotrophy was common in river locations coinciding with reported harmful algal blooms (HABs) events. Metabolism of these regulated Midwestern U.S. rivers can help assess the causes and consequences of excessive algal blooms in rivers and their role in river ecological health.

River Control Points for Algal Productivity Revealed by Transport Analysis

“…Our transport analysis could be improved by adding features or processes to better represent river storage zones (Runkel, 1998) that may themselves foster algal production and resupply the main stem after high flows (Reynolds, 1994;Rome et al, 2021), but would also increase data requirements. And in lieu of, or in addition to, increased continuous data collection, this transport analysis could be improved and validated using remote sensing (Qin & Shen, 2019), Lagrangian water quality sampling (Crawford et al, 2015;Wickland et al, 2022), or other site information such as gross primary productivity (Choi et al, 2022;Harvey et al, 2024).…”