Ecological Effects of Flow Intermittence in Gravel‐Bed Rivers

Datry, Thibault

doi:10.1002/9781118971437.ch10

Cited by 3 publications

(7 citation statements)

References 166 publications

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“…The three mesocosms with only sediment (no added OM) served as controls. The temperature treatments were based on typical isolated pool temperatures in the Albarine River in France, which were found to increased from 15°C to 25°C in the summer of 2011 (Datry, 2017). The highest temperature treatment, 30°C, was chosen as a temperature extreme, which may become a reality under increasing summer temperatures due to climate change.…”

Section: Methodsmentioning

confidence: 99%

Temperature and organic matter quantity drive CO2 and CH4 fluxes in isolated pools of non-perennial rivers

Silverthorn,

Azougui,

López-Rojo

et al. 2023

Preprint

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Rivers are important contributors to global greenhouse gas (GHG) exchange with the atmosphere. However, much less is known about biogeochemical dynamics in rivers when they dry, particularly in isolated pools created by drying. Our objective was to examine the effects of water temperature and allochthonous organic matter (OM) quantity on carbon dioxide (CO2) and methane (CH4) fluxes in isolated pools. We used an automated analyzer to measure CO2 and CH4 from 36 mesocosms filled with sediments and water from a non-perennial river, with temperature (20, 25, 30 °C) and Alnus glutinosa leaf litter (2g, 5g, 10 g) manipulations in triplicate. We found positive individual effects of water temperature and OM quantity on CO2 fluxes, and a synergistic effect of water temperature and OM on CH4 fluxes during the late stages of the incubation. Given the increase in water temperature and OM inputs in rivers associated with climate change, our results indicate an associated increase in CO2, and a disproportionate increase in CH4 fluxes to the atmosphere, potentially contributing towards a positive climate feedback loop.

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Section: Methodsmentioning

confidence: 99%

Temperature and organic matter quantity drive CO2 and CH4 fluxes in isolated pools of non-perennial rivers

Silverthorn,

Azougui,

López-Rojo

et al. 2023

Preprint

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“…Conversely, Johnson et al (2014) highlighted that tributary inputs facilitated notable longitudinal variations in T w during a non‐drought summer. Reduced advective upstream inputs becomes most prevalent when flow cessation events occur, such as systems exclusively fed by groundwater inputs (i.e., no upstream contributions—White et al, 2018) or hydrologically disconnected instream pools that undergo rapid warming (Datry, 2017).…”

Section: Processes Governing Drought‐induced River Water Temperature:...mentioning

confidence: 99%

“…The effects of upstream advective influences (surface water contributions) on T w is dependent on the thermal properties and relative discharges of the mainstem channel and inflowing tributaries. For instance, in northeast Scotland, Hrachowitz et al (2010) (Datry, 2017).…”

Section: The Influences Of Water Source Contribution On River Water T...mentioning

confidence: 99%

Drought impacts on river water temperature: A process‐based understanding from temperate climates

White,

Khamis,

Dugdale

et al. 2023

Hydrological Processes

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High river water temperature (Tw) extremes have been widely reported during drought conditions as extreme low‐flows often coincide with high atmospheric energy inputs. This has significant implications for freshwater ecosystem health and sustainable river management practices globally. However, the extent to which different meteorological and hydrological processes interact during droughts to govern Tw dynamics, and how this varies between environmental contexts, remains poorly understood. Here, we review the mechanisms controlling Tw dynamics during droughts across temperate, maritime environments, using the United Kingdom as a detailed case study. We evidence that Tw spikes have widely occurred during extreme low‐flow events observed within droughts, but such trends have been inconsistent due to varying hydroclimatic conditions and river basin controls. To better understand this, we re‐conceptualize the mechanisms governing drought‐induced Tw dynamics operating across three ‘process sets’: (i) ‘energy flux dynamics’ as non‐advective controls on Tw; (ii) the role of ‘reach‐scale habitat conditions’ in mediating non‐advective controls on Tw, including hydraulic properties (e.g., residence time) and physical conditions (e.g., riparian vegetation coverages, wetted perimeters); (iii) ‘water source contributions’ (surface water and groundwater) as advective heat and water flow controls. We review natural and anthropogenic influences affecting Tw controls within each process set and discuss how such mechanisms are likely to change under drought conditions. More systematic research (spanning various river environments and drought severities) is required to test such concepts, with existing scientific knowledge on drought‐induced Tw dynamics being largely gleaned from studies examining non‐extreme low‐flow conditions or with broader focuses (e.g., annual thermal dynamics). We conclude by highlighting critical future research questions that need to be answered to better model Tw dynamics during future droughts and for unmonitored sites. Such scientific advances would more effectively inform how high Tw extremes could be better managed through evidence‐based mitigation and adaptation strategies.

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“…When a channel shifts from lotic to lentic conditions, biological communities also change abruptly towards pond‐like communities (Anna et al, 2009; Bonada et al, 2020; Hill & Milner, 2018). However, if pools remain disconnected, many can become unviable for most organisms due to high temperatures, low dissolved oxygen and concentrated nutrients (Datry, 2017; Woelfle‐Erskine et al, 2017). In some cases, active hyporheic inflow can replenish pools with cool and oxygenated water (Anna et al, 2009; Bonada et al, 2020).…”

Section: The ‘Typical’ Ecohydrology Of Iresmentioning

confidence: 99%

“…Prolonged water deficit during a drought induces a suite of physico‐chemical changes (Gómez et al, 2017) that occur faster and are more severe than during regular flow cessation events, thus exposing the biota to extreme conditions compared to normal years. For example, during a drought, temperature rose from 14 to 25°C, and dissolved oxygen decreased from 12 to 4 mg L −1 in 2 weeks in three pools of the Albarine River in France (Datry, 2017), exceeding physiological thresholds for many aquatic species (Vander Vorste, Mermillod‐Blondin, Hervant, Mons, & Datry, 2016). Typically, dissolved oxygen and pool volume quickly decrease once riffles become disconnected while temperature and conductivity increase, with salinity sometimes reaching exceptionally high levels (Bae & Park, 2019; Golladay et al, 2004; Lind et al, 2006; Obedzinski et al, 2018; Woelfle‐Erskine et al, 2017).…”

Section: Ecohydrological Interactions In Ires During Droughtsmentioning

confidence: 99%

Drought in intermittent river and ephemeral stream networks

2021

Self Cite

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Intermittent rivers and ephemeral streams (IRES), those watercourses that periodically cease to flow or dry, are the world's most widespread type of river ecosystem.Our understanding of the natural hydrology and ecology of IRES has greatly improved, but their responses to extreme events such as drought remain a research frontier. In this review, we present the state of the art, knowledge gaps and research directions on droughts in IRES from an ecohydrological perspective. We clarify the definition of droughts in IRES, giving recommendations to promote transferability in how ecohydrological studies characterize droughts in non-perennial stream networks. Based on a systematic search of the literature, we also identify common patterns and sources of variation in the ecological responses of IRES to droughts and provide a roadmap for further research to enable improved understanding and management of IRES during those extreme hydrological events. Confusion in the terminology and the lack of tools to assess the hydrological responses of IRES to drought may have hindered the development of drought research in IRES. We found that 44% of studies confused the term drought with seasonal drying and that those that measure droughts in a transferable way are a minority. Studies on ecological responses to drought in IRES networks are still rare and limited to a few climatic zones and organisms and mainly explored in perennial sections. Our review highlights the need for additional research on this topic to inform IRES management and conservation.

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Ecological Effects of Flow Intermittence in Gravel‐Bed Rivers

Cited by 3 publications

References 166 publications

Temperature and organic matter quantity drive CO2 and CH4 fluxes in isolated pools of non-perennial rivers

Temperature and organic matter quantity drive CO2 and CH4 fluxes in isolated pools of non-perennial rivers

Drought impacts on river water temperature: A process‐based understanding from temperate climates

Drought in intermittent river and ephemeral stream networks

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