Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

Wind farms and the distribution and abundance of Aurelia aurita in the south-western Baltic Sea

This study assessed the impact of secondary hard substrate, as being introduced into marine ecosystems by the establishment of wind farm pillars, on the occurrence and distribution of the moon jelly Aurelia aurita in the southwestern Baltic Sea. Wind farms as well as other fixed offshore installations such as platforms, piles and pillars act as artificial reefs. These provide substrate for organisms which would not be able to settle on the original soft sediments. This issue is of high relevance in the western Baltic Sea where predominant soft-sediments limit the spectrum of organisms. An organism that might benefit from this additional secondary hard substrate is the moon jellyfish Aurelia aurita. The generation of renewable energy by offshore wind farms is likely to increase significantly in the western Baltic Sea. Several studies suggest that anthropogenic installations might favour problematic occurrence of massive numbers of jellyfish .


The results of our study confirm that anthropogenic created hard substrate (e.g. offshore wind farms) has the potential to increase the abundance of the Aurelia aurita population.

A two-year data sampling was conducted with removable settlement plates to assess the distribution and population development of the scyphozoan polyps. The data collected from these samples were used to set up a model with Lagrangian particle technique which was used to simulate the distribution of juvenile A. aurita for 12 years. A general interesting result of this research is that some open sea areas (central Arkona and Bornholm Basin) as well as the northern coastal and shallower regions of the Bornholm Basin exhibit a low probability of medusae occurrence. Secondly, there are predictions obtained for other areas to be permanently associated with high abundances of medusae (e.g. Kattegat). The relative final mean distributions of all released drifters show that the majority of juvenile medusae remained within the release areas, transport between the release areas as well as losses out of the release areas were only of minor importance.


The distribution of wind farm borne jellyfish along Danish, German and Polish coasts indicates conflicts with further sectors, mainly energy and tourism.

Spatial analyses of the drift patterns show a strong transnational dimension of the distribution of wind farm borne jellyfish. In the given example most of the planned wind farms are located in waters under German administration. The majority of A. aurita individuals released from them, however, are drifting into non-German waters (approx. 70%). Here especially Danish waters were affected where more than a half of all drifters move to. The distribution of wind farm borne jellyfish along Danish, German and Polish coasts indicates conflicts with further sectors, mainly fisheries and tourism. Increased appearance of A. aurita may impede coastal tourism, e.g. on Darss peninsula, as tourists often perceive jellies in general as annoying. And A. aurita is able to clog fishing nets and the distribution if wind farm borne jellies partly overlaps with areas of intense fishing effort. However, so far there are no reports abo ut clogged fishing nets in the Baltic Sea.

Relevance for Policy:
  • Alien Invasive Species Directive
  • Convention on Biological Diversity
  • Directive on Maritime Spatial Planning and Integrated Coastal Management (forthcoming)
  • Environmental Impact Assessment Directive
  • EU Biodiversity Strategy
  • Habitats and Birds Directive
  • Integrated European Maritime Policy (IMP)
  • Marine Strategy Framework Directive
  • Strategic Environmental Assessment Directive

Lead Author:

Holger Janßen
Leibniz Institute for Baltic Sea Research (IOW)
Date of research: July 2014

Related articles:

The impacts of wind farms on oxygen conditions 

Co-existence in busy seas: the primary sectors 

Economic analysis of offshore wind farms project 

Extreme ecological events and jellyfish outbreaks

Tourist’s valuation of climate change impacts 

Understanding policy and legal frameworks

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
© Vectors 2015. Coordinated by Plymouth Marine Laboratory.