Global prevalence of non-perennial rivers and streams

Messager, Mathis L.; Lehner, Bernhard; Cockburn, Charlotte; Lamouroux, Nicolas; Pella, Hervé; Snelder, Ton; Tockner, Klement; Trautmann, Tim; Watt, Caitlin; Datry, Thibault

doi:10.1038/s41586-021-03565-5

Cited by 341 publications

(237 citation statements)

References 106 publications

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“…Then, the potential for population recovery following drought was severely compromised by the impacts of numerous in-stream barriers which individually and collectively acted to severely limit opportunities for fish to move and repopulate depleted habitat patches. While our study focuses on dryland rivers of the northern portion of Australia's Murray Darling Basin, reliance of fish populations upon refugia and movement for their viability are characteristic of nonperennial rivers everywhere, with a recent estimate such rivers constitute up to 60% of the global river network (Messager et al, 2021). Therefore, our results have global relevance.…”

Section: Discussionmentioning

confidence: 93%

Risks to Fish Populations in Dryland Rivers From the Combined Threats of Drought and Instream Barriers

Marshall

Lobegeiger

Starkey³

2021

Front. Environ. Sci.

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In dryland rivers, flow intermittency means fish populations are often subjected to drought disturbance. The viability of these fish populations depends on the availability of waterhole refuges for individuals to survive drought (resistance) and the ability of surviving fish to repopulate the rivers by recruitment and dispersal once flow returns (resilience). In this study we combined remote-sensed mapping of the locations of waterholes that lasted through an extreme drought in the northern Murray Darling Basin, Australia, with an assessment of the impacts of in-stream barriers on limiting the opportunities for fish to move and repopulate after drought. We found that at the peak of this 2018–2020 drought, the worst on record for some rivers and the most spatially synchronous recorded across the region, waterholes were few and generally small – representing only 11% of the total river channel network. All the fish in the region that survived the drought were concentrated into this limited waterhole refuge habitat. Even small instream structures, such as minor weirs, caused large reductions in the opportunities for fish to move between river segments when there is flow. Almost all the 104 instream structures assessed reduced long-term fish movement opportunities, measured as days with discharge greater than calculated barrier drown out thresholds, by more than 70% and up to 100%, when compared to opportunities for movement if the barrier was not present. This large impact from small instream barriers is a consequence of flow intermittency and is likely to reduce fish population resilience and impact the capacity of fish populations to recover after drought. Combining information on the risks posed by limited refuge habitat availability during drought and from reduced movement opportunity following drought allowed us to identify river segments where these combined threats are the greatest risk to viability of local fish populations. Considering the spatial arrangements of these risks provides a means to systematically prioritize mitigation measures such as weir removal to improve fish movement opportunities and local management of key waterholes to increase drought resistance. The approach used here provides a guide for assessing and prioritizing the management of fish population viability risks from drought and fragmentation by barriers in any non-perennial river setting.

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Section: Discussionmentioning

confidence: 93%

Risks to Fish Populations in Dryland Rivers From the Combined Threats of Drought and Instream Barriers

Marshall

Lobegeiger

Starkey³

2021

Front. Environ. Sci.

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“…Over 50% of the global stream network is intermittent, experiencing flow cessation and drying at some points in space and time (Acuña et al 2014). The frequency, duration and magnitude of intermittency are expected to dramatically increase in response to climate change and growing water use (Messager et al 2021). In arid and semiarid regions, intermittent streams are the dominant surface water type (Datry et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream

et al. 2021

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Droughts are recognized to impact global biogeochemical cycles. However, the implication of desiccation on in-stream carbon (C) cycling is not well understood yet. We subjected sediments from a lowland, organic rich intermittent stream to experimental desiccation over a 9-week-period to investigate temporal changes in microbial functional traits in relation to their redox requirements, carbon dioxide (CO2) and methane (CH4) fluxes and water-soluble organic carbon (WSOC). Concurrently, the implications of rewetting by simulated short rainfalls (4 and 21 mm) on gaseous C fluxes were tested. Early desiccation triggered dynamic fluxes of CO2 and CH4 with peak values of 383 and 30 mg C m−2 h−1 (mean ± SD), respectively, likely in response to enhanced aerobic mineralization and accelerated evasion. At longer desiccation, CH4 dropped abruptly, likely because of reduced abundance of anaerobic microbial traits. The CO2 fluxes ceased later, suggesting aerobic activity was constrained only by extended desiccation over time. We found that rainfall boosted fluxes of CO2, which were modulated by rainfall size and the preceding desiccation time. Desiccation also reduced the amount of WSOC and the proportion of labile compounds leaching from sediment. It remains questionable to which extent changes of the sediment C pool are influenced by respiration processes, microbial C uptake and cell lysis due to drying-rewetting cycles. We highlight that the severity of the dry period, which is controlled by its duration and the presence of precipitation events, needs detailed consideration to estimate the impact of intermittent flow on global riverine C fluxes.

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“…Flow intermittence alters carbon processing Ecological implications at river-network scale Intermittent rivers are the most predominant lotic ecosystem worldwide (Messager et al 2021). Given their capacity to accumulate large amounts of organic matter during the dry phase (Datry et al 2018), intermittent rivers often experience hot moments (sensu McClain et al 2003) of microbial processing of C during rewetting events (Marcé et al 2019;Shumilova et al 2019).…”

Section: Resultsmentioning

confidence: 99%

“…For example, the combination of land use heterogeneity, instream processing and hydrological mixing triggers chemical diversity of dissolved organic matter along river networks (Casas-Ruíz et al 2020;Peter et al 2020), We suggest hydrological dynamics of intermittent tributaries could create a powerful mechanism of chemical diversification of leaf litter at local and river network scale with unknown consequences for decomposition dynamics. Intermittent rivers represent over half of the global river network length and this fraction will likely increase due to climate and global change (Messager et al 2021); therefore, accounting for dry-phase-associated diversity effects could be critical to achieve a mechanistic understanding and realistic modeling of C fluxes at regional and global scale (Marcé et al 2019).…”

mentioning

confidence: 99%

Flow intermittence alters carbon processing in rivers through chemical diversification of leaf litter

Campo

Corti

Singer

2021

Limnol Oceanogr Letters

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The dry phase of intermittent rivers promotes the accumulation of leaf litter on various terrestrial and aquatic habitats. This environmental heterogeneity causes a chemical diversification of leaf litter by a range of physical and biological degradation processes acting across the various habitats. After flow resumption, the chemically diversified leaves are mixed and subject to continued decomposition downstream. We hypothesized that the chemical diversification of leaf litter during the dry phase would affect leaf litter decomposition under re‐established lotic conditions. Our laboratory treatments mimicking dry‐phase habitats caused a strong chemical diversification of leaf litter, which—upon combination in mixed litter bags—accelerated its decomposition in a perennial river reach. We suggest that intermittent rivers may act as hotspots of organic matter diversification, with potential implications for organic matter processing at the river‐network scale.

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Global prevalence of non-perennial rivers and streams

Cited by 341 publications

References 106 publications

Risks to Fish Populations in Dryland Rivers From the Combined Threats of Drought and Instream Barriers

Risks to Fish Populations in Dryland Rivers From the Combined Threats of Drought and Instream Barriers

Desiccation time and rainfall control gaseous carbon fluxes in an intermittent stream

Flow intermittence alters carbon processing in rivers through chemical diversification of leaf litter

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