Biodiversity in temporary rivers – The impact of climate change
To date, few river studies have focused on the effect of a gradient of flow intermittence on the richness, density and traits of macroinvertebrates living in and around temporary streams. However, the importance of dry riverbeds in maintaining the diversity of groups of both terrestrial and aquatic species, and thus regulating the transfer and transformation of energy and materials and defining the resilience of the system, has been recently highlighted. The aim of the CLITEMP (Climate change effects on aquatic and terrestrial invertebrate assemblages in European rivers: The influence of duration of dry period in temporary rivers) project was to investigate how the duration, extent and severity of the dry period control the make-up of assemblages of both terrestrial and aquatic organisms. The resulting data can be used to predict the effects of climate change on biodiversity and ecosystem processes in European rivers. Biologists analysed changes in community structure and composition and in biological traits of groups of macroinvertebrates along a gradient of flow intermittence in temporary rivers. Scientists also studied the effects of different habitats on macroinvertebrate communities and the impact of extending the period when the riverbed is dry on terrestrial invertebrates, and on the links between aquatic and terrestrial organisms. Results showed that temporary rivers act as corridors for terrestrial invertebrates moving along the river course between patches of water and other suitable habitats. This supports the hypothesis that flow intermittence is a master variable, driving river assemblage structure and composition and the distribution of biological traits. It was found that when the length of dry periods increased, the number of species within assemblages of invertebrates decreased. CLITEMP will have a significant impact on research, management and monitoring of temporary streams and rivers. It will also directly affect the bioassessment of temporary streams with regard to the European Water Framework Directive (WFD). The project's findings will help water managers to reformulate the current bioassessment and monitoring schemes for temporary river basins, where the effect of flow intermittence on aquatic vertebrate communities has generally been neglected until now.
Keywords
Temporary rivers, climate change, flow intermittence, riverbeds, invertebrates, bioassessment
