Do intermittent and ephemeral Mediterranean rivers belong to the same river type?

Argyroudi, Anna; Chatzinikolaou, Y.; Poirazidis, Κonstantinos; Lazaridou, Maria

doi:10.1007/s10452-008-9176-9

Cited by 42 publications

(11 citation statements)

References 39 publications

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“…This finding is supported by the results from studies of invertebrate population genetics in streams that show that dry reaches act as barriers for weak or moderate aerial dispersers, such as some Ephemeroptera, dispersing within dry channels (Chester, Miller, Valenzuela, Wickson, & Robson, 2015). When not totally dry, lentic conditions prevailing in stream channels during dry phases are often associated with high temperature and low dissolved oxygen, (Anna, Yorgos, Konstantinos, & Maria, 2008; Boulton, 2003), which could potentially create desert areas for aerial dispersers with selective oviposition behaviour. Alternatively, if pools are used for oviposition, poor water quality may decrease egg or larval survival, thus limiting settlement and spread of aerial dispersers (Alp, Indermaur, & Robinson, 2013; Encalada & Peckarsky, 2007; Lancaster & Downes, 2018).…”

Section: Discussionmentioning

confidence: 99%

Fragmentation promotes the role of dispersal in determining 10 intermittent headwater stream metacommunities

et al. 2020

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Dispersal, defined as the movement of individuals among local communities in a landscape, is a central regional determinant of metacommunity dynamics in ecosystems. Whereas both natural and anthropogenic ecosystem fragmentations can limit dispersal, previous attempts to measure such limitations have faced considerable context dependency, due to a combination of spatial extent and associated environmental variability, the wide range of dispersal modes, and abilities of organisms or variation in network topologies. Therefore, the role dispersal plays compared to local environmental filtering in explaining metacommunity dynamics remains unclear in fragmented dendritic ecosystems. We quantified α‐ and β‐diversity components of invertebrate metacommunities across 10 fragmented headwater stream networks and tested the hypothesis that dispersal is the primary determinant of biodiversity organisation in these dynamic and spatially constrained ecosystems. Alpha‐diversity was much lower in intermittent than perennial reaches, even long after rewetting, indicating an overwhelming effect of drying including a legacy effect on local communities. Beta‐diversity was never correlated with environmental distances but predominantly explained by spatial distances accounting for river network fragmentation. The nestedness proportion of β‐diversity was considerable and reflected compositional differences where communities from intermittent reaches were subsets of perennial reaches. Altogether, these results indicate dispersal as the primary process shaping metacommunity dynamics in these 10 headwater stream networks, where local communities recurrently undergo extinction and recolonisation events. This challenges previous conceptual views that local environment filtering is the main driver of headwater stream metacommunities. As river networks become increasingly fragmented due to global change, our results suggest that some freshwater ecosystems currently driven by local environment filtering could gradually become dispersal‐limited. In this perspective, shifts from perennial to intermittent flow regimes represent ecological thresholds that should not be crossed to avoid jeopardising river biodiversity, functional integrity, and the ecosystem services they provide to society.

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Section: Discussionmentioning

confidence: 99%

Fragmentation promotes the role of dispersal in determining 10 intermittent headwater stream metacommunities

et al. 2020

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“…, 2004). Comparable intermittent assemblages of specialised, rapidly developing (<8 weeks) stoneflies, blackflies and midges have been found in short flow‐duration streams in Canada (Williams & Hynes, 1976), Australia (Towns, 1985; Boulton & Lake, 1992), the United States (Abell, 1984; Miller & Golladay, 1996) and Europe (Anna et al. , 2009), and as such may be useful as a global indicator assemblage for intermittent flow conditions in ungauged streams.…”

Section: Discussionmentioning

confidence: 99%

Flow intermittency alters longitudinal patterns of invertebrate diversity and assemblage composition in an arid‐land stream network

2013

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Summary 1. Temporary streams comprise a large proportion of the total length of most stream networks, and the great majority of arid‐land stream networks, so it is important to understand their contribution to biotic diversity at both local and landscape scales. 2. In late winter 2010, we sampled invertebrate assemblages in 12 reaches of a large arid‐land stream network (including perennial and intermittent headwaters, intermittent middle reaches and perennial rivers) in south‐east Arizona, U.S.A. Intermittent reaches had then been flowing for c. 60 days, following a dry period of more than 450 days. We sampled a subset of the perennial study reaches three more times between 2009 and 2011. Since intermittent reaches were dry during these additional sampling periods, we used assemblage data from two other intermittent streams in the study network (sampled in 2004–05 and 2010) to explore interannual variability in intermittent stream assemblage composition. 3. Invertebrate richness was lowest in intermittent reaches, despite their often being connected to species‐rich perennial reaches. The assemblages of these intermittent reaches were not simply a subset of the species in perennial streams, but rather were dominated by a suite of stoneflies, blackflies and midges with adaptations to intermittency (e.g. egg and/or larval diapause). On average, 86% of individuals in these samples were specialists or exclusive to intermittent streams. Predators were 7–14 times more abundant in perennial than in intermittent reaches. 4. Despite being separated by long distances (12–25 km) and having very different physical characteristics, the assemblages of perennial headwaters and rivers were more similar to one another than to intervening intermittent reaches, emphasising the prime importance of local hydrology in this system. 5. The duration and recurrence intervals of dry periods, and the relative importance of dispersal from perennial refuges, probably influence the magnitude of biological differences between neighbouring perennial and temporary streams. Although perennial headwaters supported the highest diversity of invertebrates, intermittent reaches supported a number of unique or locally rare species and as such contribute to regional species diversity and should be included in conservation planning.

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“…Less-predictable or more-ephemeral streams may support biological communities that differ more from those in perennial streams than what we observed. Anna et al (2008) found large differences in bioassessment indices between ephemeral and intermittent streams, and Gallart et al (2012) found that unpredictable hydrologic regimes decreased the measured ecological status of temporary streams. Therefore, bioassessment tools developed from perennial streams may provide comparable interpretations only at nonperennial streams with sufficient relative flow permanence.…”

Section: Assessment Tools Work In Nonperennial Streamsmentioning

confidence: 99%

Aquatic invertebrate community structure along an intermittence gradient: Selwyn River, New Zealand

Arscott

Larned

Scarsbrook

et al. 2010

Journal of the North American Benthological Society

120

144

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Do intermittent and ephemeral Mediterranean rivers belong to the same river type?

Cited by 42 publications

References 39 publications

Fragmentation promotes the role of dispersal in determining 10 intermittent headwater stream metacommunities

Fragmentation promotes the role of dispersal in determining 10 intermittent headwater stream metacommunities

Flow intermittency alters longitudinal patterns of invertebrate diversity and assemblage composition in an arid‐land stream network

Aquatic invertebrate community structure along an intermittence gradient: Selwyn River, New Zealand

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