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

Abstract

Intermittent rivers, which experience periods of flow cessation and streambed drying, occur globally. Given that the frequency and duration of stream drying events is likely to increase as a result of anthropogenic pressures and global climate change, riverbed sediments may become increasingly important as refuge habitat for benthic macroinvertebrates. Our study examined the effect of surface water loss and increasing drying duration on the survivorship of the most abundant benthic invertebrate, Gammarus pulex (L.) (Amphipoda: Gammaridae), inhabiting the wet subsurface sediments of exposed gravel bars within a perennial stream and a connected temporarily flowing side channel. G. pulex survivorship declined more over time during drying conditions compared to control conditions (flowing water present).Survivorship was greater in the temporary channel and may reflect the greater water retention capacity of fine sediments in the subsurface and abiotic stability compared to the free-draining exposed gravel bars on the main channel. Our results illustrate that saturated subsurface sediments may facilitate G. pulex persistence during surface drying events and highlight the need for effective refuge management and conservation for instream fauna during drying events.

Life‐history traits are poor predictors of species responses to flow regime change in headwater streams

“…Freshwater species of Amphipoda are known to be able to retreat to the hyporheos to withstand temporary stream drying (Stubbington, 2012; Vadher et al, 2018). However, although the amphipod Uroctena sp.…”

Extreme low‐flow effects on riverine fauna: A perspective on methodological assessments

“…In addition, we acknowledge that some field-based assessments and controlled experiments may be inherently linked, but the results published separately (e.g. Vadher et al, 2018aVadher et al, , 2018b and/or may be interwoven within larger research projects like PhD theses (e.g. Dewson, 2007;Picken, 2021).…”

Body size affects the vertical movement of benthic amphipods through subsurface sediments in response to drying

“…Channel drying and loss of surface water results in distinct species assemblages (Leigh et al, 2016;Bogan et al, 2017;Mathers et al, 2019a), characterised by fauna exhibiting resistance and resilience traits to surface water drying such as use of atmospheric oxygen (Stanley et al, 1994), desiccationresistant life stages (Stubbington et al, 2016), or the ability to rapidly recolonize following the rewetting and resumption of favourable conditions (Vander Vorste et al, 2016a;Pařil et al, 2019). Although surface water may not be available, water may persist in subsurface sediments (hyporheic zone) which may provide a potential refuge for macroinvertebrates (Williams & Hynes, 1974;Vadher et al, 2018a). However, the refuge potential may be highly variable depending on water table depth (Vander Vosrte et al, 2016b) and the nature of surface-groundwater exchange (Folegot et al, 2018).…”