Dispersal Capacity Influences the Recovery of Biodiversity

Pollutants from industry, households, and agriculture are placing significant pressure on our rivers. Although numerous restoration measures have improved water quality in the past and enabled a partial recovery of biodiversity, this positive trend has stagnated. An international research team led by Prof. Dr Peter Haase (Senckenberg/University of Duisburg-Essen) has identified species' dispersal capacity as a key factor in the recolonisation of restored rivers. The findings were recently published in the scientific journal Global Change Biology.

As early as 2023, Haase’s team highlighted in a widely recognised Nature publication that, despite improved water quality, the recovery of biodiversity has stagnated since 2010. The researchers now provide an explanation: “Dispersal capacity is a crucial factor,” says Haase. “It determines whether a species can colonise new or restored habitats—either through active movement such as swimming or flying, or through passive dispersal, for instance via water currents. This capacity significantly influences genetic mixing and resilience to environmental changes.”

For the study, the research team analysed data from 1,327 time series spanning the period from 1968 to 2021, covering 23 European countries. The analysis revealed that in recovering rivers, species diversity increased, particularly among species with high dispersal capacity—including swimming and drifting organisms as well as insects with large wings, such as diving beetles and caddisflies. By contrast, in deteriorating water bodies, species richness declined, and the proportion of highly mobile species decreased.

However, this trend varied locally, and improved water quality did not always result in the return of highly mobile species. “To make river restoration more effective, conservation measures should enhance landscape connectivity to better link habitats. This is particularly important for the integration of species-rich ‘source’ populations, which play a crucial role in successful recolonisation. In light of climate change, flexible strategies are also required to adapt to shifting environmental conditions, enhance ecosystem resilience, and ensure the long-term effectiveness of conservation efforts,” says Dr Carlos Cano-Barbacil, the study’s lead author and a postdoctoral researcher in Haase’s group.

More Information

Publication: Cano-Barbacil C, Sinclair JS, Welti EAR, Haase P. Recovery and Degradation Drive Changes in the Dispersal Capacity of Stream Macroinvertebrate Communities. Glob Chang Biol. 2025 31(1): e70054.

https://doi.org/10.1111/gcb.70054

Press release by The University of Duisburg-Essen (UDE), author Juliana Fischer