Responses of ground‐dwelling arthropods to surface flow drying in channels and adjacent habitats along Mediterranean streams

Abstract

Intermittent streams are dynamic ecosystems that alternate between dry and wet states. Despite their global dominance, we have scant information about the effects of surface flow drying on terrestrial arthropods in channel and adjacent terrestrial habitats. In the present study, we used pitfall traps to characterise the terrestrial arthropod assemblages along lateral gradients (channel, riparian, and upland habitats) in perennial and intermittent reaches of two contrasting Mediterranean intermittent streams (Rogativa and Fuirosos streams). Simultaneously, we assessed changes in assemblage composition and structure on five sampling occasions over the entire drying period (i.e. 29 days). The composition of arthropod assemblages differed among streams, flow regimes, habitat types, and sampling dates. In contrast, depending on the stream, taxonomic richness and total abundance were similar between perennial and intermittent reaches, but differed among habitat types. Formicidae, Araneae, Collembola, and Coleoptera explained most of the differences between flow regimes and habitat types in both streams. In Rogativa stream, arthropod abundances peaked in the dry channel and increased with drying time, while abundances decreased in riparian and upland habitats. It implies that the dry channel may be colonized by riparian and upland arthropods to a greater or lesser extent depending on the stream and the specific landscape context. Our results emphasize the importance of dry channels as temporary habitats for terrestrial arthropod assemblages. Thus, the dry period should be considered explicitly when assessing biodiversity of and establishing management strategies for intermittent streams and their fringing riparian and upland areas.Values in italics indicate statistical significance at P < 0.05. GROUND-DWELLING ARTHROPOD ASSEMBLAGES IN INTERMITTENT STREAMS

Temporary streams in temperate zones: recognizing, monitoring and restoring transitional aquatic‐terrestrial ecosystems

“…Globally, TS research remains freshwater‐focussed, with few studies of dry‐channel ecology and fewer still that integrate terrestrial and aquatic components . Such integrative research is needed to improve understanding of spatiotemporal variability in community composition as ecosystems transition between lotic, lentic, and terrestrial states .…”

High Variability Is a Defining Component of Mediterranean-Climate Rivers and Their Biota

“…For example, in California, Mazor et al [118] demonstrated acceptable performance of current biomonitoring indices such as the Southern California Index of Biotic Integrity (IBI) for many intermittent streams. Moreover, innovative approaches, such as one based on terrestrial fauna [119,120] are being developed.…”

Dissimilarity in the riparian arthropod communities along surface water permanence gradients in aridland streams

“…Although ground-dwelling arthropod communities frequently do not change during seasonal drying in intermittent river reaches (Corti & Datry, 2014;McCluney & Sabo, 2012;O'Callaghan, Hannah, Boomer, Williams, & Sadler, 2013), there is strong and significant divergence in composition between perennial and intermittent reaches in a variety of streams (Corti & Datry, 2016;Ellis, Crawford, & Molles, 2001;Sánchez-Montoya et al, 2016). Our study differs from prior work (e.g., Corti Ellis et al, 2001;Sánchez-Montoya et al, 2016) in that we examine community dissimilarity over spatial and seasonal gradients along multiple stream channels over multiple years and that we examine both nestedness and turnover components of beta diversity over this spatial gradient. Our study differs from prior work (e.g., Corti Ellis et al, 2001;Sánchez-Montoya et al, 2016) in that we examine community dissimilarity over spatial and seasonal gradients along multiple stream channels over multiple years and that we examine both nestedness and turnover components of beta diversity over this spatial gradient.…”

“…Here, we build on this body of work and compare richness (alpha diversity) and differences in composition (beta diversity) at the landscape scale across a replicated set of stream channels with perennial headwaters and intermittent to ephemeral lower reaches. Our study differs from prior work (e.g., Corti & Datry, 2016;Ellis et al, 2001;Sánchez-Montoya et al, 2016) in that we examine community dissimilarity over spatial and seasonal gradients along multiple stream channels over multiple years and that we examine both nestedness and turnover components of beta diversity over this spatial gradient. Specifically, we aim to test whether nestedness or turnover explains dissimilarity in ground-dwelling riparian arthropod community composition along replicated gradients of streamflow permanence.…”

“…Further, a variety of grounddwelling arthropods rely on aquatic-derived resources (Juliano, 1986;Paetzold et al, 2005;Sanzone et al, 2003); thus, the composition of these communities may shift with decreasing surface water permanence. Although ground-dwelling arthropod communities frequently do not change during seasonal drying in intermittent river reaches (Corti & Datry, 2014;McCluney & Sabo, 2012;O'Callaghan, Hannah, Boomer, Williams, & Sadler, 2013), there is strong and significant divergence in composition between perennial and intermittent reaches in a variety of streams (Corti & Datry, 2016;Ellis, Crawford, & Molles, 2001;Sánchez-Montoya et al, 2016). Here, we build on this body of work and compare richness (alpha diversity) and differences in composition (beta diversity) at the landscape scale across a replicated set of stream channels with perennial headwaters and intermittent to ephemeral lower reaches.…”