Testing the Performance of Macroinvertebrate‐Based Indices of Intermittence in Rivers Beyond Their Region of Development

Intermittent rivers represent more than half of the length of the global river network, and their extent is predicted to increase. Although flow intermittence is a natural phenomenon, it is exacerbated by the combined and interacting effects of climate change and anthropogenic pressures. This increasing intermittence represents a major threat to freshwater biodiversity and highlights the pressing need for indices that can assess the responses of freshwater biota to drying events. However, most such indices remain untested beyond their region of origin, limiting their widespread use. We addressed this gap by testing the capacity of two macroinvertebrate-based indices that respond to flow intermittence (the drought effect of habitat loss on invertebrates [DEHLI] index and the monitoring intermittent streams index [MIS-index]), developed and evaluated in United Kingdom, to distinguish between perennial and intermittent river sites in Italy. Scores for both indices and index-derived richness metrics (i.e., the taxa richness of groups of environmental association classified by the indices) were higher at perennial than at intermittent sites. Among index-derived richness metrics, only those including rheophilic taxa were lower at intermittent sites, whereas others were comparable at perennial and intermittent sites. Our results suggest that both indices have the potential for use beyond their original region of development, with a better performance of the DEHLI index due to its family-level taxonomic resolution. However, their responsiveness could be enhanced by regional adaptation to increase the pool of scoring taxa. In addition, the development of conceptual frameworks predicting assemblage composition in intermittent rivers across different biogeographical regions could guide the future development of new indices for flow intermittence.