German Federal Agency for Nature Conservation (BfN)

Mainmenu



Impacts on marine species and habitats


Harbour porpoise (Phocoena phocoena). Photo: Katrin Wollny-Goerke
Harbour porpoise (Phocoena phocoena). Photo: Katrin Wollny-Goerke

Noise harms marine mammals

One of the most severe impacts of the construction of offshore wind turbines relates to marine mammals and most notably the harbour porpoises that are native to German waters. The pile driving noise generated in construction of wind turbine foundations is well above the tolerance limits identified by scientists for these animals and can cause temporary hearing impairment (and thus a massive hindrance to food seeking) or even severe injury. At greater distances – up to 20 km or more for pile driving without noise mitigation – the sound pulses trigger stress and behavioural responses that often cause the animals to flee their home grounds. Underwater noise can also drown out acoustic communication between porpoises, interfering with their orientation and ability to find prey.

Other native marine mammals such as common and grey seals, fish and some invertebrates are likewise affected by noise.

Further information on the impacts of noise on marine species is provided under Underwater Noise.


Range of responses in seabirds

Black-throated diver (Gavia arctica). Photo: Sven-Erik Arndt
Black-throated diver (Gavia arctica). Photo: Sven-Erik Arndt

The North Sea and the Baltic Sea provide a resting, feeding and wintering habitat for numerous seabirds. Responses to offshore wind farms vary from species to species. While some gull species appear to be attracted to wind farms, others such as guillemots and northern gannet occur less frequently in wind farm areas after construction than before. Disturbance-sensitive divers (red-throated and black-throated divers) in particular largely avoid the spaces between turbines and their populations only reach past densities at distances several kilometres away from a wind farm; they thus suffer a loss of habitat going far beyond the area enclosed by wind farms themselves.

In long-term monitoring in the German Bight, the area of the Sylt Outer Reef was identified as a primary concentration area for the two diver species, with up to 66 percent of the German North Sea diver population gathering there every spring. The approval of further offshore wind farms in this particular area is therefore unjustifiable for nature conservation reasons. The use of wind power in the German North Sea must thus be prevented from resulting in habitat loss that could endanger the populations of these species.

See also Position paper on the assessment of diver habitat loss (only in German):
Positionspapier des Geschäftsbereichs des Bundesumweltministeriums zur kumulativen Bewertung des Seetaucherhabitatverlusts durch Offshore-Windparks in der deutschen AWZ der Nord- und Ostsee als Grundlage für eine Übereinkunft des BfN mit dem BSH

Research into the impacts of offshore wind turbines on seabirds was also carried out during the construction and operation phase of the alpha ventus wind farm. In regular ship and aircraft surveys, it was found that out of all key seabird species in the test area, the populations of six of the observed species (the divers mentioned above, common guillemot, northern gannet and lesser black-backed gull) were smaller after completion of the construction work than before it started. With the exception of the lesser black-backed gull, these species avoid the area of the wind farm and the immediate surroundings, which ultimately means a permanent loss of habitat for them.


Blue mussel and sea anemone growth on a wind turbine foundation. Photo: Roland Krone, AWI
Blue mussel and sea anemone growth on a wind turbine foundation. Photo: Roland Krone, AWI
Longspined bullhead (Taurulus bubalis) on a wind turbine foundation. Photo: Roland Krone
Longspined bullhead (Taurulus bubalis) on a wind turbine foundation. Photo: Roland Krone

Wind turbine foundations as introduced hard substrate

There is ongoing debate about the possible ecosystem impacts of wind turbine foundations and their scour prevention structures, which have the effect of artificial reefs. Studies on the alpha ventus test site showed a local increase in diversity due to growth on wind turbine foundations. In the North Sea especially, which is dominated by soft sediment and associated benthic communities, the foundations and scour prevention structures create artificial surfaces for colonisation by hard substrate species that do not occur naturally at all in these locations. So far, however, there has evidently been no colonisation by species not native to the German North Sea, meaning that the increase in diversity is indeed only local. It is not yet possible to predict the long-term effects of this change in natural local ecological communities as a result of large-scale wind farms.

Waste from growth on foundation structures and dead plants and animals add organic material to the surrounding sea floor. In certain conditions – notably in the Baltic Sea in areas poorly flushed by currents – this can lead to oxygen-depleting decomposition processes and ultimately the death of the original communities.

Impacts of submarine cables

Studies have shown that electromagnetic fields and heat given off by power cables leading onshore from wind farms can harm mussels, worms, electrosensitive cartilaginous fish such as sharks and rays, and also bony fish such as eels. More information on this topic is provided under Submarine Cables und Grid Connection (only in German).

Map North Sea

Offshore Wind Farms, Grid Connections and Natura 2000 Sites in the German Exclusiv Economic Zone (EEZ) of the North Sea.

Offshore Wind Farms, Grid Connections and Natura 2000 Sites in the German Exclusiv Economic Zone (EEZ) of the North Sea. (As of 03.2015)

Map Baltic Sea

Offshore Wind Farms, Grid Connections and Natura 2000 Sites in the German Exclusiv Economic Zone (EEZ) of the Baltic Sea.

Offshore Wind Farms, Grid Connections and Natura 2000 Sites in the German Exclusiv Economic Zone (EEZ) of the Baltic Sea. (As of 03.2015)

 Print