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Abstract Studies of stream macroinvertebrates traditionally use sampling methods that target benthic habitats. These methods could underestimate biodiversity if important assemblage components exist outside of the benthic zone. To test the efficacy of different sampling methods, we collected paired reach‐wide benthic and edge samples from up to 10 study reaches in nine basins spanning an aridity gradient across the United States. Edge sampling targeted riparian‐adjacent microhabitats not typically sampled, including submerged vegetation, roots, and overhanging banks. We compared observed richness, asymptotic richness, and assemblage dissimilarity between benthic samples alone and different combinations of benthic and edge samples to determine the magnitude of increased diversity and assemblage dissimilarity values with the addition of edge sampling. We also examined how differences in richness and assemblage composition varied across an aridity gradient. The addition of edge sampling significantly increased observed richness (median increase = 29%) and asymptotic richness (median increase = 173%). Similarly, median Bray–Curtis dissimilarity values increased by as much as 0.178 when benthic and edge samples were combined. Differences in richness metrics were generally higher in arid basins, but assemblage dissimilarity either increased or decreased across the aridity gradient depending on how benthic and edge samples were combined. Our results suggest that studies that do not sample stream edges may significantly underestimate reach diversity and misrepresent assemblage compositions, with effects that can vary across climates. We urge researchers to carefully consider sampling methods in field studies spanning climatic zones and the comparability of existing data sets when conducting data synthesis studies. 

Freshwater species face numerous threats across the globe, including urbanization. Within cities in regions with drier climates, dewatering and channelization of rivers commonly occur and reduce or eliminate freshwater biodiversity. The discharge of effluent (treated wastewater) has been used to restore flow in some of these rivers, but our knowledge is negligible about how ecological communities develop and change in these unique but increasingly common ecosystems. In this study, we quantified aquatic macroinvertebrate community development in the Santa Cruz River (Arizona, U.S.A.), where effluent‐restored flow more than 100 years after the river dried up. We tracked community development over a 2‐year period in reaches where flow had been restored and compared those findings with data from a reference reach. Our study period also encompassed a massive disturbance where effluent releases temporarily ceased and sediment was dredged from the channel, allowing us to quantify the impacts of urban channel maintenance activities on recovering communities. Macroinvertebrate colonization was rapid following the initial flow restoration and channel dredging, with density and species richness values reaching or exceeding those of the reference reach within a few months, but community composition remained quite distinct after 2 years. Flow duration and the number of dry days in the month prior to sampling were the most influential factors in macroinvertebrate metrics. Simply adding effluent to dewatered urban rivers has the potential to restore diverse aquatic fauna, but targeted reintroductions may be needed for sensitive or dispersal‐limited taxa.