Greening Blue Energy - BioTools For Business

Marine impacts
Annexe 1 – see Section 9.1 for more details
Mitigation options
• To minimise collision risk, placement of wind
farms in important migration corridors should
be avoided.
• The alignment of turbines could be considered,
and turbines could be made more visible for
birds.
• Illumination could also be adjusted to a level
that maintains vessel navigation safety, but
reduces the potential attraction of birds.
Threat: Seabed changes
Deployment of wind turbines and scour protection
will result in a ~1-3% direct loss of seabed within
the farm area, with each installation claiming up
to 450 m2. The abundances of fish and crabs are
likely to increase as a result of the physical structures
added, and as a consequence densities of
benthic prey can decrease in proximity to wind turbines.
The suggested radius of influence on biomass
of prey and macroalgae around an artificial reef
ranges between 15 m and 100 m. The entrapment
and deposition of organic matter, including material
that originates from fish and sessile organisms on
and around an artificial reef, can influence benthic
communities up to 40 m away and cause localised
changes in composition of macro-invertebrate
assemblages as well as changes in physico-chemical
and other parameters adjacent to the structure.
Filtration by the large numbers of blue mussels on
the turbines could, according to one study, deplete
phytoplankton and, as a result, cause lower biomass
of filter feeding animals on the seabed up to
20 m from a turbine. These impacts should only be
of significance in protected habitats where vulnerable
species are present or where the scale of the
development is substantial. Wind farms also provide
hard substrata (including shallow sections) to
areas otherwise often dominated by sedimentary
seabed and thus change the dispersal patterns and
distribution of reef dwelling species.
22 GREENING BLUE ENERGY - Identifying and managing biodiversity risks and opportunities of offshore renewable energy
Utgrunden Wind Farm, Sweden. Photo Gunnar Britse
Annexe 1 – see Sections 4 and 5 for more details
Threat: Navigational hazards/oil spills
The increase in number of industrial facilities in
coastal and offshore waters as a result of offshore
renewable energy development may amplify navigational
hazards for ships, particularly where wind
farms claim areas of deeper water greater than 20
m in depth. This increases the risks of oil spills and
other types of marine pollution. A wind turbine for
example could rip the side of a vessel and cause an