Intermittent streams that periodically cease surface flow have long been understudied in ecology and underrepresented in conservation policy. However, they currently account for 30-50% of the global river network, and that number is rising due to anthropogenic water extraction, land-use change, and climate change. We explored the Coleoptera biodiversity of the south Pacific-coast region of British Columbia, Canada, using pitfall traps at perennial and naturally-intermittent stream reaches, in shoreline, dry streambed, and riparian habitats, in both flowing (spring/early summer) and non-flowing (late summer) phases. We found that habitats around perennial reaches had significantly greater abundance of Coleoptera than those around intermittent reaches. However, neither habitat type nor flow regime were significant predictors of taxon richness, and intermittent stream sites featured unique taxa that were not found near perennial streams. This aligns with recent results from other taxonomic groups, finding that intermittent ecosystems can host high taxonomic diversity of Coleoptera, on par with or even greater than that of perennial streams. Because intermittent streams will likely become more prevalent within the global river network, we urgently need a better understanding of how different species use these habitats, which can inform appropriate biodiversity conservation efforts and flow management.

The dataset was collected in 2021 around four stream reaches in coastal British Columbia. Each row of data represents a pooled sample comprising six pitfall traps. Traps were deployed in either riparian habitat around the streams, or on the streambank (for flowing streams) or streambed (for dry streams), for an average of seven days per deployment period. Coleoptera individuals were identified to the lowest possible taxonomic level in the laboratory, using a microscope, species identification keys, and species lists from relevant areas. At the same time that pitfall traps were deployed, soil samples were collected from the same locations. Soil moisture was calculated by weighing soil samples before and after drying them in an oven, and ash-free dry mass (AFDM) was calculated after combusting subsamples of soil in a muffle furnace.