Impacts /Interactions for Offshore wind energy sector

As OWFs increase in number and size, there’s a growing need to consider their cumulative impacts on marine habitats and wildlife. 
While the effects of one wind farm on a particular wildlife population may be negligible, the aggregate effects of multiple wind farms through space and time are likely to cause wildlife population declines, while also adding to the pressures generated by other maritime sectors. 
Stressors causing these impacts are shown below. 

Pressures, intensity and occurrence of impacts on marine habitats and animal groups during the four OWF lifecycle phases

The level of OWF impacts is highly dependent on the habitat characteristics of an individual site, the types of turbines and foundations used, and the installation techniques involved. It should also be noted that OWFs may sometimes have beneficial effects for some organisms, for instance by acting as artificial reefs, which can enhance biodiversity and increase food sources.
Floating wind farms will likely have different impacts to fixed wind farms, but they are a recent development and research is so far scarce. 

●    Collision risk – bird fatality rates vary widely by region, ranging from 8-14 per year per turbine in Germany, to a shocking 100-1,000 in the Baltic Sea
●    Noise – pile driving during construction can displace dolphins by up to 50km, while operational noise is audible to some whale species at up to 18km
●    Metal pollution – a single turbine’s sacrificial anodes input 0.5-1 tonne of metals into the marine environment every year
●    Damaged seabed habitats – a single turbine ‘footprint’ on the seafloor can be above 2,000m2 
●    Cable laying and cable landing can have an impact on sensitive coastal habitats such as Posidonia beds


More info:
Final recommendations of the PHAROS4MPAs project regarding the wind energy sector in the Mediterranean.
Full capitalization report about the offshore wind energy sector.