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Stream metabolism, encompassing gross primary production and ecosystem respiration, reflects the fundamental energetic dynamics of freshwater ecosystems. These processes regulate the concentrations of dissolved gases like oxygen and carbon dioxide, which in turn shape aquatic food webs and ecosystem responses to stressors such as floods, drought, and nutrient loading. Historically difficult to quantify, stream metabolism is now measurable at high temporal resolution thanks to advances in sensor technology and modeling. The StreamPULSE dataset includes high-frequency sensor data, metadata, and modeled estimates of ecosystem metabolism. This living dataset contributes to a growing body of open-access data characterizing the metabolic pulse of stream ecosystems worldwide. To contribute to StreamPULSE, visit data.streampulse.org. All data contributed to StreamPULSE become public after an optional embargo period. Use this publication to access annual data releases, or use data.streampulse.org to download new data as they become available. 

Abstract Freshwater wetlands process large amounts of nutrients originating from agricultural fields. Yet, these systems also have the potential to produce substantial amounts of nitrous oxide (N₂O) and methane (CH₄), both potent greenhouse gasses (GHGs). Agricultural land use alters delivery of nutrients and carbon (C) to downstream wetlands, and changing climate is altering hydroperiods. These drivers modulate wetland microbial processes responsible for GHG production including denitrification and methanogenesis. Studies have correlated GHGs to C quantity and nutrients independently; fewer studies identify how nutrients and C composition interact to modulate GHG concentrations in wetlands. In wetlands located in Indiana, USA, we studied how CH₄, N₂O, and carbon dioxide (CO₂) correlated to C quantity and composition, nutrient concentrations, size, hydrology, and surrounding agricultural land use. CH₄production was correlated to dissolved organic carbon (DOC) concentrations and composition using UV‐Vis spectroscopy. CH₄concentrations were positively correlated to spectral slope from 275 to 295 nm, an indicator of autochthonous primary production, and negatively correlated to humification index. N₂O concentrations positively correlated to total dissolved nitrogen and humification index (HIX). CH₄concentrations were highest in the large wetland with negligible canopy cover, dense macrophytes and algae, and high concentrations of autochthonous‐like DOC. Thus, we suspect phototrophic methanogenesis is an important driver of CH₄variation across systems. Concentrations of N₂O were highest in the agricultural wetland, likely driven by higher NO₃⁻concentrations. Our findings suggest agricultural nutrients strongly shift greenhouse gas production profiles but do not necessarily increase global warming potential of GHGs released by wetlands. 

Mean annual temperature and mean annual precipitation drive much of the variation in productivity across Earth's terrestrial ecosystems but do not explain variation in gross primary productivity (GPP) or ecosystem respiration (ER) in flowing waters. We document substantial variation in the magnitude and seasonality of GPP and ER across 222 US rivers. In contrast to their terrestrial counterparts, most river ecosystems respire far more carbon than they fix and have less pronounced and consistent seasonality in their metabolic rates. We find that variation in annual solar energy inputs and stability of flows are the primary drivers of GPP and ER across rivers. A classification schema based on these drivers advances river science and informs management. 

Abstract Sunlight can oxidize dissolved organic carbon (DOC) to dissolved inorganic carbon (DIC) in freshwaters. The importance of complete photooxidation, or photomineralization, as a sink for DOC remains unclear in temperate rivers, as most estimates are restricted to lakes, high latitude rivers, and coastal river plumes. In this study, we construct a model representing over 75,000 river reaches in the Connecticut River Watershed (CRW), USA, to calculate spectrally resolved photomineralization. We test the hypothesis that photomineralization is a negligible DOC sink across all reaches and flow conditions relative to DOC fluxes. Our model quantifies reaction rates and transport drivers within the river reaches for the ranges of flow conditions, incoming solar irradiance, and canopy cover shading observed throughout the year. Our model predicts average daily areal photomineralization rates ranging from 1.16 mg‐C m⁻² day⁻¹in low flow river reaches in the winter, to 18.33 mg‐C m⁻² day⁻¹in high flow river reaches during the summer. Even for high photomineralization fluxes, corresponding photomineralization uptake velocities are typically at least an order of magnitude smaller than those reported for other instream processes. We calculate DOC elimination by photomineralization relative to DOC fluxes through individual stream reaches as well as the entire riverine portion of the CRW. We find that relative photomineralization fluxes are highest in summer drought conditions in low order streams. In median flows and mean light intensities, for an average watershed travel distance, 3%–5% of the DOC fluxes are eliminated, indicating that photomineralization is a minor DOC sink in temperate rivers. 

Abstract The increasing availability of high‐frequency freshwater ecosystem metabolism data provides an opportunity to identify links between metabolic regimes, as gross primary production and ecosystem respiration patterns, and consumer energetics with the potential to improve our current understanding of consumer dynamics (e.g., population dynamics, community structure, trophic interactions). We describe a conceptual framework linking metabolic regimes of flowing waters with consumer community dynamics. We use this framework to identify three emerging research needs: (1) quantifying the linkage of metabolism and consumer production data via food web theory and carbon use efficiencies, (2) evaluating the roles of metabolic dynamics and other environmental regimes (e.g., hydrology, light) in consumer dynamics, and (3) determining the degree to which metabolic regimes influence the evolution of consumer traits and phenology. Addressing these needs will improve the understanding of consumer biomass and production patterns as metabolic regimes can be viewed as an emergent property of food webs.