Ecological Indicators (Sep 2024)
A modelling approach to assess climate change impacts on taxonomic and functional diversity of European stream macroinvertebrates: Implications for water quality monitoring
Abstract
Climate change is predicted to influence freshwater ecosystems by altering water temperature and seasonal discharge, as well as the frequency and magnitude of extreme events (i.e., droughts, floods, and heatwaves). Such alterations are expected to impact the distribution of freshwater organisms, modifying the structural and functional characteristics of aquatic communities. In this study, we first modelled the present and future (2050 and 2080) distribution of environmentally suitable areas (ESAs) for nearly 600 freshwater macroinvertebrate taxa across Europe using long-term average and extreme event estimates for river water discharge based on hydrological models and changes in air temperature. Next, we calculated the functional diversity of species assemblages across the time horizons and assessed how ESA gains/losses would impact functional richness across Europe. Finally, we calculated three widely adopted biological indices used to perform the ecological status assessment of rivers in Europe for the different time horizons to analyse how these indices would be contingent on changes in future ESAs. Our results show that the number of ESAs is projected to decrease significantly by 40 % in several parts of South and West Europe, while it is expected to increase in North and North-East Europe by 60 %, suggesting potential changes in taxonomic richness and composition along a latitudinal gradient due to climate change. Conversely, functional richness was projected to vary less (±10 %) in the whole study area across the time horizons, highlighting a discrepancy between taxonomic and functional change magnitude. Lastly, projected gains/losses of ESA are likely to result in significant changes in the biological indices, indicating that the baseline conditions for determining the ecological status of European rivers should be re-assessed due to the influence of climate change.
