Biodiversity in perennial and intermittent rivers: a meta‐analysis

Abstract

Comprehensive knowledge of the effects of disturbances on biodiversity is crucial for conservation and management, not least because ecosystems with low biodiversity may be the most vulnerable. In rivers, the role of disturbance in shaping aquatic biodiversity has mainly focused on floods. Perennial rivers (PRs) often flood, whereas intermittent rivers (IRs) flood, stop flowing and dry. Despite the recent and significant increase in research on IRs, controversy remains about whether they are more or less biodiverse than PRs. Our aim was to determine (Q1) if PRs and IRs differ in biodiversity and (Q2) if the direction and magnitude of the differences (effect sizes) are related to environmental (climate, season, habitat, longitudinal zonation and anthropogenic disturbance) and/or biological factors (taxonomic group). We conducted a meta‐analysis on 44 published studies of PR and IR biodiversity that had replicated data. We applied random effects models to the data to obtain weighted mean effect sizes for differences between PRs and IRs, and their confidence intervals, by first considering all studies and then by splitting studies into groups on the basis of the above factors. We found that biodiversity was significantly higher in PRs than in IRs (Q1). We also detected significant differences (PRs> IRs) in studies of macroinvertebrates, in those conducted within arid and temperate climates, dry and wet sampling seasons, headwaters, and regions subject to different levels of anthropogenic disturbance (Q2). Our meta‐analysis suggests that the expected increase in the prevalence of IRs in certain regions of the world due to global change could result in a decrease in freshwater biodiversity. To better manage and preserve aquatic biodiversity under future global change scenarios and to avoid potential ecosystem consequences of biodiversity loss, conservation efforts should be targeted towards those environmental conditions or taxonomic groups with significant differences (PRs > IRs).

Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation

“…The same pattern with latitude was also found for phylogenetic beta-diversity. When comparing perennial and intermittent/temporary streams and rivers globally, the metanalysis by Soria et al [479] indicated that perennial rivers were generally more diverse, in terms of taxonomic richness and diversity of macroinvertebrates, fish, and diatoms than intermittent rivers. However, this was not the case for Mediterranean-climate regions, for which perennial and intermittent rivers were equally diverse.…”

Freshwater conservation planning informed and validated by public participation: The Ebro catchment, Spain, as a case study

“…One of the criticisms of the workshop participants was that the proposed RPAs included intermittent and ephemeral reaches. Despite these streams having lower biodiversity values than their perennial counterparts (Soria, Leigh, Datry, Bini, & Bonada, ), their conservation value should not be underestimated (Acuña et al, ). They hold particular species with adaptations to withstand or to recover from dry periods (Bogan et al, ), they have particular ecological dynamics (Datry et al, ; McIntosh et al, ; von Schiller, Bernal, Dahm, & Martí, ), and they provide numerous ecosystem services (Datry et al, ).…”

Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter

“…Despite their widespread distribution and distinct role in biogeochemical cycling, IRES are notably missing in current analyses of global carbon budgets and other biogeochemical processes such as cycling of nutrients and DOM (Datry et al, ). Still, research on IRES is based primarily on studies spanning fine spatial extents (Leigh et al, ), which limits our understanding of their roles in ecosystem processes at the global scale (Datry et al, ; Skoulikidis, Sabater et al, ; von Schiller et al, ; but see Datry et al, ; Soria, Leigh, Datry, Bini, & Bonada, ). The contribution of IRES particularly to biogeochemical processes must be understood and quantified to correctly estimate carbon and nutrient fluxes.…”