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BONUS BALTCOAST: BONUS BALTCOAST Case Study Germany: Eco-technologies & eutrophication in the Szczecin (Oder) Lagoon

Type of Entry: Case Study
Website: http://www.baltcoast.net/mussel-farming.html
Duration: 01/04/2015 - 30/03/2018


Due to high riverine nutrient loads, Szczecin Lagoon has a poor water quality, low transparency and an insufficient ecological status. Negative eutrophication impacts such as algae blooms, hypoxia and fish kills have occurred especially during summer months and could cause economic problems for fisheries and tourism. Hence, the sustainable development of the whole region is hampered. Previous studies have indicated that even maximum nutrient load reductions seem not to be sufficient to achieve a non-eutrophic state. Therefore, supplementary internal measures are needed to increase nutrient retention and improve the environmental quality. Vice versa, they are an option to boost the regional development, if they can be linked with EU`s Blue Growth strategy.


  • To apply the Systems Approach Framework and carry out a full ESE assessment to assess the ecological and economic implications of mussel farming in the Szczecin lagoon;
  • To raise awareness and acceptance of mussel farming as internal measures to improve water quality in coastal waters;
  • To develop concrete scenarios to foster the region´s sustainable development.


  • The case study was initiated by the Leibniz Institute for Baltic Sea Research Warnemünde in cooperation with the Coastal Union Germany (EUCC-D) within the scope of the BONUS BALTCOAST project. 

ICZM tools applied within the case study:

  • Systems Approach Framework;
  • Stakeholder Mapping;
  • Sustainability Indicators;
  • Stakeholder Preference and Planning Tool.

Case study site highlights and experiences that can be exchanged:

  • The Systems Approach Framework (SAF) provides a useful tool for ICZM, by providing guidance and all necessary step stones for a successful management;
  • To work with concrete, tailor-made, pre-defined and spatially explicit scenarios was very beneficial for the stakeholder involvement process and helped in generating a discussion among stakeholders and for the identification of additionally required information;
  • Mussel farming in Szczecin Lagoon can help to boost the region´s sustainable development, if it is combined with positive side effects, like an increased touristic use;
  • Due to the invasion of an alien Dreissena species, the implementation of a mussel farm in Szczecin Lagoon failed due to the nature protection regulations, but new approaches like swimming islands, which are used to grow macrophytes, could profit from the outcome.




  • Holistic assessment with consideration of ecological, economic and social implications;
  • Development and application of an ecological model consisting of a 3D-hydrographical-biogeochemical model and a mussel module, which was then to used to estimate the impacts of the tailor-made scenarios;
  • High spatial resolution allows detailed assessments of environmental impacts of single mussel farms on water body and sediment as well as the optimization of the mussel farm structures and locations;
  • Application of the stakeholder preference and planning tool allowed to include stakeholders personal weighting of the single criteria and scenario preferences.


  • The long duration between the two stakeholder meetings made it necessary to explain the background. The need for an improved water quality was not accepted by all stakeholders;
  • Not all questions on the potential impacts of mussel farms on the ecosystem (especially fish and avifauna) could be answered at the stakeholder events.


  • There is high demand for mussels as protein rich feed either as fresh feed or for mussel meal production and in Szczecin Lagoon Dreissena spp. occurs naturally, so that mussel farming is an option to combine the regions development by providing new job opportunities with the local improvement of the water quality, which is required e.g. by WFD. Using mussel farms to improve the water transparency at suitable bathing spots could further gather new touristic uses and boost the regional development further.


  • The sale of produced mussels is quite uncertain and requires a fast processing. In the region, the demand for mussels is very low, hence suitable transport ways would be necessary;
  • It is unclear, how the local fish and bird communities would react to the increase of mussel biomass, or if they would feed from the farmed mussels;
  • Implementing sea-based measures to improve the water quality, which got worse due to the high nutrient loads from land, means that there is a shift from the “polluter-pays-principle” to a “end-of-pipe-solution”, hence mussel farms are seen very critical as nutrient retention measures;
  • Invasion of a new alien Dreissena species, which hampered the implementation process.
Keywords: Decision-making process, Estuary and lagoon, Fishery and Aquaculture, Integrated Coastal Zone Management (ICZM)
Contact: Mr. René Friedland
Leibniz Institute for Baltic Sea Research Warnemünde / Leibniz-Institut für Ostseeforschung Warnemünde (IOW)
Seestr. 15
18119 Rostock
Telephone: +4938151970
Website: https://www.io-warnemuende.de/
Partner: The Coastal Union Germany - EUCC-D (http://www.eucc-d.de/home.html)
Linked partner: Landesamt für Umwelt, Naturschutz und Geologie (https://www.lung.mv-regierung.de/)
Linked partner: University of Greifswald (https://www.uni-greifswald.de/en/)
Linked partner: City of Ueckermünde
Financed by: BONUS BALTCOAST project has received funding from BONUS (Art 185), funded jointly by the EU and Baltic Sea national funding institutions. (https://www.bonusportal.org/)