Ecological roles and threats to aquatic refugia in arid landscapes: dryland river waterholes

Sheldon, Fran; Bunn, Stuart E.; Hughes, Jane; Arthington, Angela; Balcombe, Stephen Richard; Fellows, Christy Susan

doi:10.1071/mf09239

Cited by 171 publications

(148 citation statements)

References 85 publications

(116 reference statements)

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“…In non-perennial watercourses maximal and minimal fluxes 556 may occur during hydrologic phase transitions, and, although short-lived and problematic 557 to quantify at larger regional scales such hot and cold moments may comprise an 558 appreciable component of the local and regional carbon budgets for aquatic systems. Up 559 to 75% of watercourses in Australia are ephemeral (Sheldon et al 2010) and these non- …”

mentioning

confidence: 99%

The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange

et al. 2016

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The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water-air and soil-air exchange. Biogeochemistry, 132(1), pp. 87-102. (doi:10.1007/s10533-016-0289-2) This is the author's final accepted version.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/133460/ Ephemeral streams and wetlands are characterized by complex cycles of submersion and 26 emersion, which influence the greenhouse gas flux rates. In this study we quantify the 27 spatiotemporal variability in CO 2 and CH 4 concentrations and fluxes of an intermittent 28 first-order stream over three consecutive wet and dry cycles spanning 56 days, to assess 29 how hydrologic phase transitions influence greenhouse gas evasion. Water column excess 30 CO 2 ranged from -11 to 1600 µM, and excess CH 4 from 1 to 15 µM. After accounting for 31 temporal changes in the ratio of wet versus dry streambed hydraulic radius, total CO 2 -C 32 fluxes ranged from 12 to 156 mmol m -2 d -1 , with an integrated daily mean of 61 ± 25 33 mmol m -2 d -1 . Soil-air evasion rates were approximately equal to those of water-air 34 evasion. Rainfall increased background water-air CO 2 -C fluxes by up to 780% due to an 35 increase in gas transfer velocity in the otherwise still waters. CH 4 -C fluxes increased 19-36 fold over the duration of the initial, longer wet-cycle from 0.1 to 1.9 mmol m -2 d -1 . 37Temporal shifts in water depth and site-specific ephemerality were key drivers of carbon 38 dynamics in the upper Jamison Creek watercourse. Based on these findings, we 39 hypothesize that the cyclic periodicity of fluxes of biogenic gases from frequently 40 intermittent streams (wet and dry cycles ranging from days to weeks) and seasonally 41 ephemeral watercourses (dry for months at a time) are likely to differ, and therefore these 42 differences should be considered when integrating transient systems into regional carbon 43 budgets and models of global change.

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confidence: 99%

The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange

et al. 2016

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“…Here, we consider one type of intermittent streams: those that become spatially discontinuous during periods of low flow, with water persisting in isolated pools. These streams often exhibit a "boom and bust" ecology with species rapidly recolonizing newly wetted reaches from refugia during high flow periods (Sheldon et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Abiotic habitat thresholds for salmonid over‐summer survival in intermittent streams

2017

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Abstract. Intermittent streams lose surface flow during part of the year but can provide important habitat for imperiled fishes in residual pools. However, extended intermittency can drive high mortality as pool contraction decreases pool quality, and some pools dry completely. We evaluated the influence of a suite of abiotic habitat characteristics on the over-summer survival of two imperiled salmonid fishes (coho salmon Oncorhynchus kisutch; steelhead trout Oncorhynchus mykiss) at four study sites on two tributaries of Salmon Creek (Sonoma County, California, USA) from 2012 to 2014, during deepening drought conditions. Study sites spanned an intermittency gradient from continuous flow to near-dry conditions, and included alluvial and bedrock stream reaches. We estimated over-summer survival at the pool scale from fish presenceabsence data based on paired early-late summer snorkel surveys. We measured pool dimensions and water quality parameters monthly (more frequently during summer dry down) and, in 2013 and 2014, recorded water quality with continuous loggers in selected pools. We performed: (1) logistic regression in a generalized linear modeling framework to identify factors limiting over-summer survival and (2) classification trees using the random forests ensemble learning method to identify abiotic thresholds for sustaining salmonids. Results suggested that different factors governed mortality of the two species. Coho salmon, which tended to survive in large, deep pools, were limited by minimum dissolved oxygen (DO) concentrations. In contrast, steelhead trout, which tended to survive in pools with large surface area, were sensitive to pool geometry and temperature. Both species persisted for weeks in large pools with low DO levels, including in pools where at least part of the water column reached sublethal or lethal levels. Our results suggest that shallow, lateral hyporheic flow may be important for maintaining DO and temperatures suitable for sustaining salmonids in isolated pools, whereas groundwater discharge originating from deeper flow paths may generate low-DO conditions that inhibit salmonid persistence. Geomorphically complex watersheds with a variety of pool geometries and high rates of lateral hyporheic exchange are those most likely to serve as "sanctuary reaches" for imperiled Pacific salmonid populations in semi-arid regions in the context of a changing climate.

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“…sections of the rivers where there is a net movement of groundwater to surface water) are thus partly insulated from the greater hydrological variability induced by climate change (Poole and Berman 2001;CSIRO 2008). Although groundwater cannot provide flood pulses, we postulate that improved management of groundwater may help sustain floodplain and riparian vegetation, and in-channel refugia (Poole and Berman 2001;Sheldon et al 2010) and would require the current over-use of many groundwater aquifers to be stemmed (NWC 2009).…”

Section: Future Options For Freshwater Conservationmentioning

confidence: 99%

Australia's Murray - Darling Basin: freshwater ecosystem conservation options in an era of climate change

Pittock

Finlayson

2011

Mar. Freshwater Res.

194

114

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Abstract. River flows in the Murray-Darling Basin, as in many regions in the world, are vulnerable to climate change, anticipated to exacerbate current, substantial losses of freshwater biodiversity. Additional declines in water quantity and quality will have an adverse impact on existing freshwater ecosystems. We critique current river-management programs, including the proposed 2011 Basin Plan for Australia's Murray-Darling Basin, focusing primarily on implementing environmental flows. River management programs generally ignore other important conservation and adaptation measures, such as strategically located freshwater-protected areas. Whereas most river-basin restoration techniques help build resilience of freshwater ecosystems to climate change impacts, different measures to enhance resilience and reoperate water infrastructure are also required, depending on the degree of disturbance of particular rivers on a spectrum from free-flowing to highly regulated. A crucial step is the conservation of free-flowing river ecosystems where maintenance of ecological processes enhances their capacity to resist climate change impacts, and where adaptation may be maximised. Systematic alteration of the operation of existing water infrastructure may also counter major climate impacts on regulated rivers.

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Ecological roles and threats to aquatic refugia in arid landscapes: dryland river waterholes

Cited by 171 publications

References 85 publications

The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange

The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange

Abiotic habitat thresholds for salmonid over‐summer survival in intermittent streams

Australia's Murray - Darling Basin: freshwater ecosystem conservation options in an era of climate change

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