2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

6/06/2017 | 9:45 AM - 10:00 AM | MACRO-SCALE AND LOCAL DRIVERS OF ANNUAL METABOLISM IN STREAMS AND RIVERS | 302B

MACRO-SCALE AND LOCAL DRIVERS OF ANNUAL METABOLISM IN STREAMS AND RIVERS

In streams and rivers, ecosystem services integrate metabolic processes over timescales of seasons to years. Major theories of metabolism describe local, regional, and longitudinal patterns at similar timescales. In contrast, our empirical understanding of gross primary production (GPP) and ecosystem respiration (ER) derives from measurements spanning much shorter periods. Here we synthesize newly-estimated and previously published annual metabolic rates from >350 streams and rivers to understand their patterns and drivers. Metabolism varied less among than within years, suggesting that annual rates are the appropriate timescale to compare systems. Effects of drainage area on GPP varied with climate and land use, but a newly-developed light model that incorporates both local and regional factors better explained these patterns. ER was better predicted by GPP in larger channels, where more light supports production and more discharge dilutes terrestrial inputs. Net Ecosystem Production (NEP) was virtually always negative, and extreme heterotrophy occurred near pollutant discharge points (NPDES) and canal discharges. We conclude that annual metabolism of modern river networks reflects both broad-scale climatic and terrestrial patterns as well as local anthropogenic drivers.

S24 Towards a predictive freshwater ecology: using time-series data to understand and forecast responses to a changing environment
C10 Biogeochemistry
S29 Macrosystem Ecology of Aquatic Systems

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Presenters/Authors

Jim Heffernan (), Duke University, james.heffernan@duke.edu;