Riffretter

Von der Forschung zur Umsetzung: Strategien für die Wiederherstellung flacher Steinriffe

The stone reefs of the Baltic Sea consist of fields of boulders of varying sizes. They form the basis for complex marine communities: macroalgae and mussels depend on these rocky habitats for colonization, while fish need them as refuges and nurseries. Over the past two centuries, however, many reefs have been destroyed. Between 1800 and 1975, approximately 3.5 million metric tons of boulders were extracted off the Schleswig-Holstein Baltic Sea coast alone through what is known as “stone fishing.” It is estimated that approximately 5.6 km² of habitable area was lost for hard-substrate-dwelling organisms in the Baltic Sea off Schleswig-Holstein. The restoration of such stone reefs is intended to help improve the poor health of the Baltic Sea.

Objective

Riffretter aims to demonstrate the ecological and social effectiveness of restoration measures for shallow stone reefs in the western Baltic Sea. The project provides scientific support for a planned reef installation near Waabs/Boknis Eck and combines ecological research with socio-ecological analysis, environmental education, and knowledge transfer. The goal is to assess the impact of such restoration efforts on biodiversity and coastal communities, to support collaboration among the stakeholders involved in the project, to develop appropriate methods for standardized monitoring and consistent implementation, and to promote future initiatives and enhance their effectiveness through practical recommendations for action. Through close collaboration with government agencies and the involvement of local stakeholders, the project aims to contribute to the long-term and sustainable recovery of marine habitats.

Implementation

The project will be carried out in conjunction with a compensatory measure already planned and approved by the Wasserstraßen-Neubauamt (WNA) Nord-Ostsee-Kanal. Riffretter comprises five work packages:

1. Project coordination and management: Overseeing cross-project activities, identifying challenges, and implementing measures to foster team building within the project team.

2. Socio-ecological research: Survey of user interests, perceptions, as well as societal relevance, acceptance, and effectiveness.

3. Accompanying research on ecological effectiveness: Integration of methodological approaches and comparative data from preliminary surveys and studies of natural reefs, as well as monitoring the success of planned measures. Feasibility study for future non-invasive monitoring of reef colonization dynamics. Analysis of fish colonization, material comparison, and acoustic monitoring.

4. Knowledge Transfer and Sustainability: Development of guidelines for reef restoration in the Baltic Sea, network building, and communication and networking initiatives.

5. Environmental education: Communicating the importance of stone reefs to various target groups through a range of events, diving programs, and informational materials.

By integrating research, practical application, environmental education, and knowledge transfer, this initiative serves as a flagship project for reef restoration. Thanks to its transferability to future initiatives of this kind, it will contribute to the long-term improvement of the ecological condition of the Baltic Sea.

Project Partners

Associated Project Partners

Sea daisy: Stone reefs in the Baltic Sea form an ecosystem comprising a wide variety of marine life. The sea daisy, a hard-substrate dweller, finds an ideal habitat here. © S. Piepiorka, OIC

Funding:

Deutsche Bundesstiftung Umwelt

Term:

09/2026-08/2029

Contact

Dr. Christian Wagner-Ahlfs

0431-880 1554

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