Context

Rivers and streams are among the most degraded ecosystems worldwide, yet they play a crucial role in 
providing clean water, supporting biodiversity, storing carbon, and reducing flood risks. In response, restoration 
approaches that aim to improve in-stream hydromorphology, such as channel structure, flow variability, and 
habitat diversity, are increasingly implemented worldwide. However, many of these restoration efforts fail to 
achieve good ecological status or to fully recover biodiversity and ecosystem functioning. Scientific evidence 
suggests that hydromorphology strongly influences both biodiversity and ecosystem processes in rivers, 
indicating that the potential of hydromorphological restoration remains underexploited. RESTOLINK was built 
on the premise that restoration often underperforms because it does not sufficiently account for the spatial 
scales of river structure and flow that are most relevant to organisms and ecosystem functioning. In addition, 
traditional indicators of restoration success, which primarily focus on diversity and community composition, 
may show recovery trajectories different from those of key ecosystem functions, such as nutrient cycling. 

Objectives

RESTOLINK aimed to move beyond purely structural and biodiversity-based assessments of river restoration 
and to identify the ecological processes that underpin the success and resilience of stream and river 
restoration. The main objectives were to: a) Understand how physical habitat diversity and flow variability 
influence biodiversity and ecosystem functioning; b) Test whether restoring hydromorphology also restores 
key ecosystem functions; c) Examine biodiversity–ecosystem functioning relationships across contrasting 
climatic regions; d) Assess how current restoration approaches perform under climate change; and e) 
Translate scientific findings into knowledge relevant for practitioners, managers, and policy makers.

Methodology

RESTOLINK combined field measurements, laboratory analyses, and large-scale data synthesis across four 
countries representing tropical, Mediterranean, temperate, and boreal river systems. At each site, we studied 
restored, degraded, and near-natural stream reaches using a harmonised sampling design. Measurements 
included stream flow patterns and habitat structure, biodiversity ranging from microorganisms to aquatic 
invertebrates, and ecosystem functions such as nutrient uptake and organic matter processing. In addition, 
RESTOLINK analysed existing scientific studies and conducted stakeholder surveys to better understand how 
restoration is currently planned and evaluated, especially in the context of climate change.

Main results and impacts

RESTOLINK showed that habitat diversity and flow variability are key drivers of biodiversity and ecosystem 
functioning. Rivers with more diverse physical conditions support richer biological communities and more 
efficient ecosystem processes. At the same time, the project demonstrated that biodiversity often recovers 
faster than ecosystem functioning, meaning that the return of species does not automatically translate into fully 
restored ecosystem performance. By comparing rivers across different climates, RESTOLINK confirmed that 
positive links between biodiversity and ecosystem functioning are widespread, while also revealing that many 
restoration strategies remain focused on past environmental conditions and are poorly adapted to increasing 
droughts and floods. These findings highlight the need for climate-resilient restoration approaches that 
explicitly target ecosystem functioning.

Societal relevance and use

RESTOLINK provides practical guidance for river restoration by showing how projects can be designed to 
better support biodiversity, ecosystem functioning, and long-term resilience. The results are directly relevant 
for river basin management, environmental agencies, and policy frameworks such as the EU Water Framework 
Directive and the EU Biodiversity Strategy for 2030. By improving how restoration success is assessed, 
RESTOLINK supports more effective and sustainable use of public investments in nature.

Project website

https://restolink.weebly.com/

Key publications:

• Pasqualini, J., Anlanger, C., Mendoza-Lera, C., Fink, P., Lorke, A., Weitere, M., da Rocha, U. N., Knöller, K., Meador, T., & Brauns, M. (2026). Low-Head Dam Removal Restores Biofilm Structure but Not Function in a Temperate Stream. International Review of Hydrobiology, 111(1), e70027. https://doi.org/10.1002/iroh.70027
• Anlanger, C., Noss, C., Risse-Buhl, U., Brauns, M., von Schiller, D., Weitere, M., & Lorke, A. (2026). Linking hydromorphological diversity to biodiversity and functioning in running waters. Limnology and Oceanography, 71(5), e70385. https://doi.org/10.1002/lno.70385