Challenges, developments and perspectives in intermittent river ecology

Abstract

Summary Although more than half the world's river networks comprise channels that periodically cease to flow and dry [intermittent rivers (IRs)], river ecology was largely developed from and for perennial systems. Ecological knowledge of IRs is rapidly increasing, so there is a need to synthesise this knowledge and deepen ecological understanding. In this Special Issue, we bring together 13 papers spanning observational case studies, field and laboratory experiments and reviews to guide research and management in this productive field of freshwater science. We summarise new developments in IR ecology, identify research gaps and needs, and address how the study of IRs as highly dynamic ecosystems informs ecological understanding more broadly. This series of articles reveals that contemporary IR ecology is a multifaceted and maturing field of research at the interface between aquatic and terrestrial ecology. This research contributes to fresh water and general ecology by testing concepts across a range of topics, including disturbance ecology, metacommunity ecology and coupled aquatic‐terrestrial ecosystems. Drying affects flow continuity through time and flow connectivity across longitudinal, lateral and vertical dimensions of space, which aligns well with the recent emphasis of mainstream ecology on meta‐system perspectives. Although most articles here focus on the wet phase, there is growing interest in dry phases, and in the terrestrial vegetation and invertebrate assemblages living in and along IR channels. We encourage interdisciplinary studies on IRs to further blur the demarcation between aquatic and terrestrial ecosystems and develop more integrated perspectives. As a result of climate change and human modification of landscapes and waterways, flooding and drought are expected to become more extreme and widespread. Shifts in streamflow regimes from perennial to intermittent may exacerbate the duration and frequency of dry phases in IRs with serious implications for river ecosystems and the quality and diversity of services they provide.

Parallels and contrasts between intermittently freezing and drying streams: From individual adaptations to biodiversity variation

“…To date, ecological research on IRES has mainly focused on drying streams (Datry, Fritz, & Leigh, ; Leigh et al., ) and freezing ecology of aquatic environments in streams has not been thoroughly studied. In particular, studies on the ecological effects of total water column and bottom freezing in stream channels are scarce, making it difficult to make general conclusions about the effects of freezing on FIRES biodiversity.…”

A classification approach to reconstruct local daily drying dynamics at headwater streams

“…Due to their upstream position in the network, their size, and their high reactivity to natural or human disturbances, HS are generally naturally prone to flow intermittence (Datry, Larned, & Tockner, ; Fritz et al, ). Intermittent rivers and ephemeral streams (IRES) are defined by periodic flow cessation and may experience partial or complete dry up at some location in time and space (Datry, Fritz, & Leigh, ; Larned et al, ; Leigh et al, ). They range from ephemeral streams that flow a few days after rainfall to intermittent rivers that recede to isolated pools (Datry et al, ).…”

Drying duration and stream characteristics influence macroinvertebrate survivorship within the sediments of a temporary channel and exposed gravel bars of a connected perennial stream

“…Intermittent rivers experience periods of surface flow cessation and typically the drying of some or all of the river bed (Bogan et al, 2015;Datry et al, 2016). These streams comprise a large proportion of the total channel length across the globe, occurring throughout climatic zones from the poles to the equator (Leigh et al, 2016a), making a significant contribution to regional biodiversity , but have typically been overlooked and excluded from national and international legislation protecting streams from anthropogenic degradation (Acuña et al, 2014(Acuña et al, , 2017.…”