2022 Early Hearing Detection & Intervention Virtual Conference

March 13 - 15, 2022

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5/24/2018 | 12:15 PM - 12:30 PM | HYDROLOGICAL CONTROLS OVER ORGANIC MATTER SUPPLY AND METABOLIC ACTIVITY IN BOREAL STREAMS | 310 A

HYDROLOGICAL CONTROLS OVER ORGANIC MATTER SUPPLY AND METABOLIC ACTIVITY IN BOREAL STREAMS

The supply of dissolved organic matter (DOM) is an important driver of biogeochemical processes in streams. In boreal landscapes, DOM inputs often derive from organic rich, riparian soils connected to streams through lateral, near-surface flowpaths. Temporal changes in the riparian water table activate/deactivate these flowpaths, with higher flows typically leading to increased DOM quantity and quality in streams. These connections also vary in space, reflecting the influence of catchment topography on the size and arrangement of lateral flowpaths entering streams. Here we use estimates of ecosystem metabolism and additions of a metabolically active dye (resazurin) to explore how the processes regulating DOM inputs shape patterns of heterotrophic activity in boreal streams. Consistent with the predicted effects of activating surficial flowpaths, variation in discharge throughout the summer and autumn in a headwater stream was associated with large (5-fold) differences in ecosystem respiration. Furthermore, additions of resazurin revealed consistent increases in metabolic activity coinciding with the location of groundwater input zones. Together, these results illustrate how the physical processes governing the activation and spatial arrangement of riparian flowpaths influence patterns of boreal stream metabolism through effects on DOM delivery.

Organic Matter
Riparian
Hydrology

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Presenters/Authors

Ryan Sponseller (), Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden, ryan.sponseller@emg.umu.se;