A landscape approach to advance intermittent river ecology

Abstract

Summary Intermittent rivers are increasingly viewed as shifting mosaics of lotic (flowing water), lentic (standing water) and terrestrial (dry riverbed) habitats. The diversity, spatial arrangement, temporal turnover and connectivity of these habitats are controlled by the magnitude, frequency, duration and extent of drying and rewetting events, which maintain habitat heterogeneity and control biodiversity and biogeochemical processes in intermittent rivers. We consider intermittent rivers as spatiotemporal landscape mosaics to identify the implications such a view has for empirical and theoretical developments in landscape and river ecology. Using observational data of flow states collected by citizen scientists along 1400 km of river channels in western France, we used landscape metrics and ecologically scaled indices for four hypothetical, aquatic species (two fish and two insects) to describe the dynamics of intermittent river mosaics for five catchments. Dry patches dominated most observation dates but flowing patches had the longest average length and occupied the greatest proportion of channel length. At the start of each summer, catchments were almost entirely composed of flowing patches but lentic and dry patches could represented up to 80% of the catchments as summer progressed. Patch dynamics were typified by high levels of spatiotemporal variability. In contrast, ecologically scaled indices did not vary greatly among catchments within species. The ecologically scaled indices representing small fish were the most affected by habitat fragmentation. Such a landscape perspective could affect understanding of biodiversity patterns and biogeochemical processes in intermittent rivers. We outline the methodological developments required to integrate landscape approaches into intermittent river research, the associated challenges and current limitations in landscape ecology tools and models and the benefits of citizen science data sets. The continued quantification of shifting habitat mosaics in intermittent rivers will provide multiple opportunities to advance river and landscape ecology.

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

“…Hence, species with low tolerance to multiple stressors are eliminated from artificial NPRS, and habitat fragmentation constrains recolonization pathways (Phillipsen and Lytle, 2013;Datry et al, 2016b). Chemical pollution derived from agricultural activity may have caused the observed decline of amphibian populations in NPRS (e.g.…”

“…Since NRPS are often considered as possessing no economic value, it is unlikely that managers are going to install flow gauging stations in these catchments; thus, mapping of NPRS could be, alternatively, achieved through citizen-science projects. In some regions of France, for example, fisher associations are mapping flow states across N3500 km of river networks, by means of visual observation (Datry et al, 2016b). Such efforts could be applied at the European scale, currently one of the goals of the Cost Action SMIRES.…”

Aquatic insects dealing with dehydration: do desiccation resistance traits differ in species with contrasting habitat preferences?

“…Although some species of water beetles resist the dry phase of temporary waters in microrefuges in situ, as adult or larvae stages (e.g., Davy-Bowker, 2002; Stubbington et al, 2016), winged adults of many species show a more resilient strategy, dispersing by flying from drying sites to more favourable wet habitats (Bilton, 2014; Strachan, Chester & Robson, 2015). The duration of exposure to drying stress during dispersal depends on specific biological traits (e.g., flight ability) and landscape configuration, i.e., the availability of suitable habitats that may serve as wet refuges and the distance and connectivity between them (Datry et al, 2016; Larned et al, 2010). But even short exposures to drying stress are challenging for flying aquatic insects, because flight activity is associated to a strong dehydration (Dudley, 2000).…”

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

“…Citizen science creates opportunities to overcome the lack of hydrological data and may contribute to densify the flow‐state observation network (Buytaert et al, ; Datry, Pella, Leigh, Bonada, & Hugueny, ; Turner & Richter, ; van Meerveld, Vis, & Seibert, ). In France, new sources of observational data are available thanks to the Observatoire National des Etiages Network (ONDE; https: //onde.eaufrance.fr; Nowak & Durozoi, ).…”