Recovering European River Invertebrate Communities Homogenize or Differentiate Depending on Anthropogenic Stress.

Area of Science:

• Ecology
• Environmental Science
• Conservation Biology

Background:

• Biodiversity loss leads to biotic homogenization, simplifying ecosystems and reducing functionality.
• Assessing conservation success often relies on local diversity metrics, overlooking broader community changes like biotic differentiation.

Purpose of the Study:

• To investigate if reduced anthropogenic stress can reverse biotic homogenization and promote biotic differentiation in European river invertebrate communities.
• To analyze how varying levels of anthropogenic stress influence trends in taxonomic and trait beta-diversity.

Main Methods:

• Analyzed 447 time series of river invertebrate communities across 48 European river basins (1994-2023).
• Measured community similarity using taxonomic and trait beta-diversity.
• Related beta-diversity trends to anthropogenic stress indicators: ecological quality, temperature increase, and land cover pressure.

Main Results:

• Beta-diversity trends were strongly mediated by anthropogenic stress; lower-stress basins showed differentiation, higher-stress basins showed homogenization.
• The direction of beta-diversity change depended on the identity of traits involved, not just gains or losses.
• Additions promoted differentiation at low stress but homogenization at high stress; subtractions showed the inverse.

Conclusions:

• Beta-diversity responds asymmetrically to anthropogenic stress, with both homogenization and differentiation occurring simultaneously.
• Conservation success assessment requires considering stress-dependent beta-diversity responses for effective ecosystem recovery.
• Understanding these responses is crucial for targeted management strategies promoting long-term ecosystem health.