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

Abstract

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 and early summer) and nonflowing (late summer) phases. We found that habitats around perennial reaches had significantly greater abundance of Coleoptera individuals than did those around intermittent reaches. However, neither habitat type nor flow regime was a significant predictor 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; that is, 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, a better understanding of how different species use these habitats is needed to inform appropriate biodiversity conservation efforts and flow management.