Neglecting biodiversity baselines in longitudinal river connectivity restoration impacts priority setting

Area of Science:

• River ecology
• Conservation biology
• Freshwater habitat restoration

Background:

• Riverine ecosystems face significant fragmentation due to artificial barriers, hindering aquatic organism movement and dispersal.
• Habitat connectivity restoration is a major goal in conservation, yet current prioritization methods often overlook species-specific population fragmentation and biodiversity baselines.

Purpose of the Study:

• To investigate the impact of neglecting biodiversity baselines on prioritizing river barrier removals for conservation.
• To develop and apply a novel modeling approach for prioritizing conservation actions in river systems.

Main Methods:

• Combined species distribution modeling with network connectivity analysis in the Rhine-Aare river system, Switzerland.
• Assessed how barrier removals affect structural and functional connectivity and species habitat suitability.
• Compared species-distribution-informed prioritization with species-agnostic metrics.

Main Results:

• High barrier density significantly reduced river connectivity and habitat suitability for aquatic species.
• Prioritization of barrier removals differed substantially when considering species' expected distributions versus simple river length.
• Barriers within areas suitable for species received higher removal priority to enhance functional connectivity.

Conclusions:

• Integrating existing barriers with species' historical and current distributions is crucial for effective river connectivity restoration.
• This approach ensures that restoration efforts maximize the recovery and long-term persistence of riverine fish diversity.