Spatial heterogeneity and controls of ecosystem metabolism in a Great Plains river network

Dodds, Walter K.; Higgs, Sophie A.; Spangler, M.; Guinnip, James P.; Scott, Jeffrey D.; Hedden, Skyler C.; Frenette, Bryan D.; Taylor, Ryland; Schechner, Anne; Hoeinghaus, David J.; Evans‐White, Michelle A.

doi:10.1007/s10750-018-3516-0

Cited by 21 publications

(12 citation statements)

References 50 publications

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“…Others are primarily temporally distributed (e.g., large diel temperature cycles, but which roughly mirror each other at locations many kilometres apart). Still others are both spatially and temporally (spatiotemporally) distributed (e.g., primary production varies in response to both spatial heterogeneity in benthic autotroph cover and diel cycles in solar insolation; Reichert, Uehlinger, & Acuña, ; Dodds et al, ). Because measurements are made in water parcels moving through both space and time, Lagrangian sampling integrates both spatial and temporal variation (Hensley et al, ) making identification of causal processes difficult (Ensign et al, ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

Hensley

Spangler

DeVito

et al. 2020

Hydrological Processes

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Stream water chemistry is traditionally measured as variation over time at fixed sites, with sparse sites providing a crude understanding of spatial heterogeneity. An alternative Lagrangian reference frame measures changes with respect to both space and time as water travels through a network. Here, we collected sensor-based measurements of water chemistry at high spatial resolution along nearly 500 km of the Upper Colorado River. Our objective was to understand sources of spatiotemporal heterogeneity across different solutes and determine whether longitudinal change manifests as smooth gradients as suggested by the River Continuum Concept (RCC) or as abrupt changes as suggested by the Serial Discontinuity Concept (SDC). Our results demonstrate that Lagrangian sampling integrates spatiotemporal variation, and profiles reflect processes that vary in both space and time and over different scales.Over each day of sampling, water temperature (T) and dissolved oxygen (DO) varied strongly in response to diel solar cycles, with most of the variation driven by sampling time rather than sampling location. Equilibration of T and DO with the atmosphere limited small scale spatial heterogeneity, with variation at the entire profile scale driven by regional climate gradients. As such, T and DO profiles more closely approximated the smooth gradients of the RCC (though including temporal sampling artefacts). Conversely, variation in specific conductance and nitrate (NO 3 -N) was largely driven by spatial patterns of lateral inflows such as tributaries and groundwater. This resulted in discrete shifts in the profiles at or downstream of discontinuities, appearing as the profiles expected with the SDC. The concatenation of spatiotemporal variation that produces observed Lagrangian profiles presents interpretive challenges but also augments our understanding of where, how, and critically why water chemistry changes in time and space as it moves through river networks.

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Section: Introductionmentioning

confidence: 99%

Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

Hensley

Spangler

DeVito

et al. 2020

Hydrological Processes

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“…These data in aggregate suggest careful determination of what constitutes a "representative" reach required to obtain results reflecting general metabolic rates in a river. Few studies we are aware of do this in addition to Reichert et al (2009), Demars et al (2015, and Dodds et al (2018).…”

Section: Discussionmentioning

confidence: 96%

How do methodological choices influence estimation of river metabolism?

Schechner

Dodds

Tromboni

et al. 2021

Limnology & Ocean Methods

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River metabolism modeled from diurnal dissolved oxygen (DO) has become a widely used metric of ecosystem function, yet many papers provide insufficient methodological detail for replication. Only 79% of 43 sampled papers published from 2015 to 2019 mention calibration, 44% describe sensor placement, and 34% did not describe estimation approaches such that the study could be replicated. Given spatial heterogeneity in rivers influences metabolism, and measurement sensitivities vary with sensor model, it is important to have appropriately detailed information in reported methods along with a fundamental understanding of how river heterogeneity might influence metabolism. We deployed 2-8 sensors at 92 steppe river reaches to characterize site heterogeneity, evaluating how sensor placement and type, deployment length, drift correction, data source, local vs. remotely sensed data, and calibration can affect metabolism estimates. Estimates of gross primary production (GPP) and ecosystem respiration (ER) were inconsistent and unpredictable depending on deployment location within a river reach; GPP and ER rates varied up to 131% and 69%, respectively, across a river width and up to two orders of magnitude within a reach. DO sensor brands vary in precision and accuracy; we found even when operated within stated performance range, estimates of GPP and ER could vary by 82% and 198%, respectively, if not calibrated beyond factory setting, as determined using field data from a sample site. Inaccuracies from sensor drift over weeklong deployments led to an average 48% ER overestimation, and 2% GPP overestimation comparing uncorrected with corrected field data. We suggest best practices for more comparable, precise, representative, and accurate methods.

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“…Estimation of reaeration rate in streams is important to properly estimate the ecosystem metabolism 3 . In this study, the reaeration rate was estimated by the BASE v2.0 model using the time series of DO data 33 , 42 , 43 . BASE v2.0 is certainly advantageous for estimating reaeration rate and thus stream metabolic rates with the statistical reliability.…”

Section: Discussionmentioning

confidence: 99%

River Metabolism along a Latitudinal Gradient across Japan and in a global scale

Gurung

Iwata

Nakano

et al. 2019

Sci Rep

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Since temperature is a key factor affecting photosynthetic and respiration rates, the rates of gross primary production (GPP) and ecosystem respiration (ER) are expected to be lower for rivers at higher latitudes, while the net ecosystem production (NEP) rate likely decrease in rivers at lower latitude due to higher sensitivity of ER to temperature compared with GPP. To examine these possibilities, we estimated the ecosystem metabolism of 30 rivers located from 43.03°N to 32.38°N in Japan during summer using a Bayesian model with hourly changes in dissolved oxygen concentrations. In addition, we examined latitudinal trends of GPP, ER and NEP in a global scale by compiling and analyzing river metabolic data estimated in previous studies. Our analysis showed that both GPP and ER tended to increase with latitude, although these rates were positively related to water temperature in Japanese rivers. Global dataset of GPP and ER also showed increasing trend towards higher latitude. In addition, contrary to our initial expectations, NEP decreased with latitude and most rivers were net heterotrophic at both regional (Japanese rivers) and global scales. These results imply that the latitudinal temperature effect on river metabolism is masked by other factors not examined in this study, such as land use in the watershed, which play pivotal roles in explaining the latitudinal variation of river metabolism.

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Spatial heterogeneity and controls of ecosystem metabolism in a Great Plains river network

Cited by 21 publications

References 50 publications

Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

Evaluating spatiotemporal variation in water chemistry of the upper Colorado River using longitudinal profiling

How do methodological choices influence estimation of river metabolism?

River Metabolism along a Latitudinal Gradient across Japan and in a global scale

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