Flow intermittence and land cover drive biotic heterogeneity in stream macroinvertebrates
metacommunities
local contribution to beta diversity; species turnover; richness difference; beta diversity; aquatic
macroinvertebrate; non-perennial rivers.
Freshwater ecosystems harbor a high biodiversity that is threatened by climate change and human
pressures. In river ecosystems, these threats are increasing the proportion of non-perennial rivers and
ephemeral streams. These rivers alternate between flowing, pool, and dry phases, supporting regional
biodiversity through communities adapted to hydrological variability. However, more frequent and
severe droughts are undermining community resilience, decreasing local diversity and changing species
composition. Furthermore, land conversion for agriculture, pasture, and urbanization alters river
hydrology. Therefore, the primary objective of this study is to investigate how flow intermittence and
land use influence the structure of aquatic macroinvertebrate metacommunities by analyzing the
components of beta diversity (species turnover and richness difference) using the Local Contribution to
Beta Diversity (LCBD) metric. We investigated nine metacommunities, each composed of several river
reaches spanning a continuum of perennial and non-perennial conditions in southeastern France. Our
results revealed that spatial factors (latitude and longitude), land use and the probability of flow
intermittence were important predictors for both species turnover and richness difference. Overall, we
observed that reaches with greater natural land cover and higher probability of flow intermittence
harbor macroinvertebrate communities with more exclusive species compositions. Consequently,
these habitats should be prioritized in conservation planning. Moreover, streams with high levels of
anthropogenic should be restored, especially through riparian reforestation.