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

Abstract

The riparian areas around streams and rivers are often thought of as distinct habitats with unique species. Research on riparian zones has traditionally focused on those bordering perennial waterways; thus, we know much less about riparian species supported by intermittent and ephemeral streams. As nonperennial streams make up the vast majority of stream channels in many landscapes, we aimed to investigate how surface water permanence affects riparian communities.We focus on riparian ground-dwelling arthropods, a group that often depends on resources derived from surface and/or ground water. We sampled riparian ground-dwelling arthropods along surface water permanence gradients in 3 replicated stream channels in southeastern Arizona to assess patterns in diversity and community similarity. We found that alpha diversity did not differ between reach types, but high species turnover led to significant community dissimilarity among perennial, intermittent, and ephemeral riparian zones. Further, intermittent and ephemeral riparian zones harbored more unique species not found at other reach types than did perennial reaches. These patterns were strongest during the dry season, when intermittent and ephemeral reaches are most likely to lack surface water. Our results suggest not only that the riparian zones of nonperennial streams host equivalent arthropod diversity to their perennial counterparts but also that these communities have little overlap with those at perennial reaches.As a result, intermittent and ephemeral stream channels should receive greater consideration than they currently do in efforts to conserve regional biodiversity.

Coleoptera associated with intermittent streams and their riparian zones in south coastal British Columbia

“…One of our most notable findings was that, in our study area, taxon richness was identical between perennial and intermittent streams, despite abundance being four times greater in the former than in the latter. These results are consistent with findings from more arid zones (Sánchez-Montoya et al 2016, 2020; Moody and Sabo 2017) and from a temperate river basin in Europe (Corti and Datry 2014). Within each study area, community composition varied among sites and between time periods, despite intermittent and perennial sites being within 100–400 m of one another and, according to our assessment, presenting comparable environmental variables.…”

“…During the flowing phase at both of our study sites, unique taxa were found at the intermittent site that were not present in the same habitat type (streambank, riparian zone) at the nearby perennial site. Previous research has attributed the dissimilarity between stream types to high taxa turnover due to the unique conditions created by patterns of flow cessation and onset (Moody and Sabo 2017). In our study, taxa from Cerambycidae, Lampyridae, and Nitidulidae were found only in habitats around the intermittent reaches.…”

Implementing an Operational Framework to Develop a Streamflow Duration Assessment Method: A Case Study from the Arid West United States

“…Positive indicators of ephemerality may lead to greater confidence in the acceptance of ephemeral classifications from an SDAM. Some studies suggest that terrestrial arthropods and non-hydrophytic plants may serve as useful indicators [ 77 , 130 , 131 ], but further exploration is needed to incorporate them into SDAMs.…”

The terrestrial and semi‐aquatic invertebrates of intermittent rivers and ephemeral streams

“…Similar patterns in invertebrate composition have been found in dry riverbeds around the world. High abundances of ants, beetles, and spiders were recorded in Australia (Steward, 2012), Italy (Steward, 2012), Namibia (Lalley et al ., 2006), USA (Moody & Sabo, 2017) and South Africa (Wishart, 2000), and high abundances of ants and springtails in New Zealand (Larned, Datry & Robinson, 2007). Wishart (2000) found that the invertebrate composition in dry riverbeds was diverse, with 19 invertebrate orders identified from just three sites.…”