Like other European countries, Germany promotes the extension of renewable energies in order to protect the atmosphere from harmful emissions. The Federal Government of Germany has set the target to double the energy production from renewable sources by the year 2010. Offshore wind farming is supposed to play a major role in order to achieve this target. The installation of offshore wind farms at a large scale has raised concerns about possible impacts on nature, especially birds and marine mammals. Amongst others, there is concern that migrating birds might collide with the turbines; this may regard slow manoeuvring birds, times of limited visibility (night, fog, low clouds etc.), attraction by the turbine lights or other circumstances. The noise emissions of constructing and operating the wind farms might disturb harbour porpoises (Phocoena phocoena). A problem of the current discussion in Germany is that empirical research is not possible, as up to now no offshore wind turbines have been erected in German waters, though several approvals have been granted. Thus, a lack of knowledge about possible ecological problems exists and aggravates the discussion of these topics.
In 2005 we started a two-year project on the responses of harbour porpoises in the Danish offshore wind farms Horns Rev in the North Sea and Nysted in the Baltic Sea. The project is financed by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. Access to the offshore wind farms was granted by the Danish Energy companies Vattenfall (formerly ELSAM eng.) and DONG energy (formerly Energi E2). Background of this study is the question, whether there are differences in the presence, echolocation activity and behaviour of harbour porpoises between inside and outside the wind farm or between close to far away (up to 1.5 km away) from a single turbine. The study was conducted with acoustic dataloggers (T-PODs) recording harbour porpoise echolocation signals. The devices were mounted on the seabed in an array of short transects with five TPODs in a row. Positions with T-PODs covered areas inside and outside the two wind farms Nysted and Horns Rev. In each wind farm area, two rows – totalling in ten devices – were deployed simultaneously. During the campaign, we changed the position of the rows four times, resulting in ten different experiments for each wind farm.
Click here to view Part I: Birds.