Drought and postdrought recovery cycles in an intermittent Mediterranean stream: structural and functional aspects

Acuña, Vicenç; Muñoz, Isabel; Giorgi, Adonis; Omella, Meritxell; Sabater, Francesc; Sabater, Sergi

doi:10.1899/04-078.1

Cited by 253 publications

(232 citation statements)

References 45 publications

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“…Hydrologic and biogeochemical differences between pools can contribute to heterogeneity in habitat quantity and quality during dry periods (Fellman et al 2011, Vazquez et al 2011. For example, drying-induced fragmentation concentrates organic matter (Towns 1985, Stanley et al 1997, Caruso 2002, which, when combined with high microbial respiration and low air-water gas exchange rates, can subsequently deplete dissolved oxygen (DO; Acuña et al 2005).…”

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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Section: Introductionmentioning

confidence: 99%

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

2017

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“…In most cases, taxa richness of aquatic macroinvertebrates was lower in NPRS than in PRS (Muñoz, 2003;Morais et al, 2004;Sánchez-Montoya et al, 2009, 2010Belmar et al, 2012;Datry, 2012;Datry et al, 2014b), but see Bonada et al (2007bBonada et al ( , 2008 and Skoulikidis et al (2011). The seasonal community composition differed between PRS and NPRS (Bonada et al, 2008); in NPRS, invertebrates exhibiting low dissolved oxygen requirements and pool-like strategies dominate during the contracting phase (Pires et al, 2000;Acuña et al, 2005;Bonada et al, 2007b;García-Roger et al, 2013), whereas resilient taxa and species with riffle-like strategies dominate during the expansion phase (Bonada et al, 2007b;Datry et al, 2014b). Overall, collectors are more abundant in NPRS than in PRS and, in particular for NPRS, the number of predators increases in remaining pools during the contracting phase (Sabater et al, 2006;Bonada et al, 2007b).…”

Section: Biotic Responses To Flow Intermittencymentioning

confidence: 99%

Non-perennial Mediterranean rivers in Europe: Status, pressures, and challenges for research and management

Skoulikidis

Sabater

Datry

et al. 2017

Science of The Total Environment

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223

134

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Non-perennial rivers and streams (NPRS) cover N 50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Contents lists available at ScienceDirect Science of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n vPlans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability -at least as far as it is possible to assess -we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems.

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“…Aquatic and terrestrial species colonize and emigrate from intermittent rivers in response to shifts between wet and dry habitat (Acuña et al, 2005;Corti and Datry, 2012;Datry et al, 2012;Davey and Kelly, 2007;Steward et al, 2011). A smaller number of intermittent river specialists persist through multiple wet-dry cycles; this group includes aestivating fish and encysting invertebrates (Kikawada et al, 2005;Perry et al, 2008;Sayer, 2005).…”

Section: T H Snelder Et Al: Regionalization Of Patterns Of Flow Inmentioning

confidence: 99%

Regionalization of patterns of flow intermittence from gauging station records

Snelder

Datry

Lamouroux

et al. 2013

Hydrol. Earth Syst. Sci.

117

127

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Abstract. Understanding large-scale patterns in flow intermittence is important for effective river management. The duration and frequency of zero-flow periods are associated with the ecological characteristics of rivers and have important implications for water resources management. We used daily flow records from 628 gauging stations on rivers with minimally modified flows distributed throughout France to predict regional patterns of flow intermittence. For each station we calculated two annual times series describing flow intermittence; the frequency of zero-flow periods (consecutive days of zero flow) in each year of record (FREQ; yr −1 ), and the total number of zero-flow days in each year of record (DUR; days). These time series were used to calculate two indices for each station, the mean annual frequency of zero-flow periods (mFREQ; yr −1 ), and the mean duration of zero-flow periods (mDUR; days). Approximately 20 % of stations had recorded at least one zero-flow period in their record. Dissimilarities between pairs of gauges calculated from the annual times series (FREQ and DUR) and geographic distances were weakly correlated, indicating that there was little spatial synchronization of zero flow. A flow-regime classification for the gauging stations discriminated intermittent and perennial stations, and an intermittence classification grouped intermittent stations into three classes based on the values of mFREQ and mDUR. We used random forest (RF) models to relate the flow-regime and intermittence classifications to several environmental characteristics of the gauging station catchments. The RF model of the flow-regime classification had a cross-validated Cohen's kappa of 0.47, indicating fair performance and the intermittence classification had poor performance (cross-validated Cohen's kappa of 0.35). Both classification models identified significant environment-intermittence associations, in particular with regional-scale climate patterns and also catchment area, shape and slope. However, we suggest that the fair-to-poor performance of the classification models is because intermittence is also controlled by processes operating at scales smaller catchments, such as groundwater-table fluctuations and seepage through permeable channels. We suggest that high spatial heterogeneity in these small-scale processes partly explains the low spatial synchronization of zero flows. While 20 % of gauges were classified as intermittent, the flow-regime model predicted 39 % of all river segments to be intermittent, indicating that the gauging station network under-represents intermittent river segments in France. Predictions of regional patterns in flow intermittence provide useful information for applications including environmental flow setting, estimating assimilative capacity for contaminants, designing bio-monitoring programs and making preliminary predictions of the effects of climate change on flow intermittence.

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Drought and postdrought recovery cycles in an intermittent Mediterranean stream: structural and functional aspects

Cited by 253 publications

References 45 publications

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

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

Non-perennial Mediterranean rivers in Europe: Status, pressures, and challenges for research and management

Regionalization of patterns of flow intermittence from gauging station records

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