Offshore wind energy: Ecological risks and how to reduce them

What is the impact of wind farms on populations of vulnerable species? How do marine mammals, fish and fish larvae behave when foundations are being driven into the sea during the construction phase? And do birds and bats experience any nuisance during operation? Wageningen Marine Research is conducting research for the government and the wind energy sector into ecological effects and which mitigating measures and innovations can help reduce ecological risks.

We are also conducting modelling research to map the cumulative long-term effects of construction at high speed and on a large scale. This includes the ecological translation of possible physical effects on the ecosystem, such as the mixing of water layers, including impacts on the productivity of food chains in the North Sea.

Risks for porpoises

Wageningen Marine Research uses aerial surveys to map populations and habitats of harbour porpoises in Dutch waters. We also study the presence and behaviour of porpoises in and around wind farms by passive acoustic monitoring (PAM) with stationary underwater hydrophones, such as continuous porpoise detectors (C-PODs). These hydrophones record the acoustic click activity of porpoises before and during construction, and around operating wind farms. By comparing data before, during and after the construction of wind farms, we gain insight into the use of space by this small whale species.

Do porpoises suffer from underwater noise?

Underwater noise may directly or indirectly harm porpoises. A possible direct effect is that porpoises, in the vicinity of a construction site, may suffer physical injury, which may be fatal. A possible indirect effect is that porpoises that avoid the disturbance have less time to forage. Research has shown that these animals can evade the construction site by up to 30 kilometres. Reduced food intake and stress from continuous noise at sea can lead to disease. In addition to pile driving for the construction of wind farms, other economic activities produce underwater noise, such as seismic research and shipping.

Our research

Developments in the population of harbour porpoises in Dutch waters
Cumulative effects of (planned) wind farms on the population of harbour porpoises, including interpretation through modelling research
Effects of mitigation measures and innovations such as the use of a bubble screen during pile driving to protect porpoises
Changes in habitat use and foraging behaviour during pile driving operations
Reactions of harbour porpoises to underwater noise from the driving of turbine foundations for wind farms
Response of porpoises to underwater noise from operating wind farms
Which locations are suitable and less suitable for wind farms
Which seasons are suitable and less suitable for pile driving at sea

Contact our experts

Publications

Risks for seals

Wageningen Marine Research maps the populations of grey and common seals annually by means of aerial surveys above the resting places in the Wadden Sea. Data collected in the Delta region is also used to create an overall picture of seals in the Netherlands. Seal migration and behaviour in the coastal zone and the open sea are studied with transmitter research.

Can we measure seal behaviour near wind turbines?

The transmitters used by the researchers from Wageningen Marine Research register the position and diving depth. This makes it possible to record the use of space per individual. In this way, insight is gained into habitats, migration routes and diving behaviour of the animals in order to catch prey. We know seals mainly as animals resting on beaches or sandbanks, but they spend most of their time at sea.

With transmitter research we also study how seals react to, for example, pile-driving activities during the construction of wind farms or to wind farms in operation. This shows that seals react to pile-driving noise up to a distance of 50 kilometres from the construction site and deviate from their normal movement and foraging behaviour.

Our research

Developments in the populations of grey and common seals in Dutch waters
Cumulative effects of (planned) wind farms on the seal population, including interpretation through modelling research
Effects of mitigating measures and innovations such as the use of a bubble screen during pile driving to protect seals
Habitats, migration and foraging in the coastal zone and in the open sea
Reactions of seals to underwater noise from the driving of turbine foundations for wind farms
Reactions of seals to underwater noise from operating wind farms
Which locations are suitable and less suitable for wind farms
Which seasons are suitable and less suitable for pile driving at sea

Contact our experts

Risks for bats

Bats also roam the seas. They can therefore become victims of the increasing number of wind turbines at sea. Most bats are observed in the autumn and to a lesser extent in the spring. These are mainly migratory species which migrate to other areas, such as the United Kingdom, in spring and autumn.

Do wind turbines cause danger to bats?

Long-term monitoring research is used by Wageningen University & Research to record the presence of bats in space and time and the species composition. This is done at fourteen locations in the North Sea.

In addition, we use transmitter research to investigate how bats fly over the sea and whether the construction of wind farms at sea could lead to bat victims. The transmitters and MOTUS receiving stations used by our researchers register the geographical position of the animals that are tagged. This makes it possible to record individual behaviour and the use of space. Thus, insight is gained into habitats and flight routes.

Our research

Cumulative effects of (planned) wind farms on the bat population including interpretation through modelling studies
Modelling tools including weather parameters to predict bat migration as accurately as possible. This information can be used, for example, to temporarily stop wind turbines at the right moments.
Flight routes and foraging behaviour of bats in the coastal zone and on the open sea
Presence and detailed flight behaviour of bats around wind turbines
Effects of mitigation measures and innovations to protect bats
Which locations are suitable and less suitable for wind farms

Contact our expert

ir. S (Sander) Lagerveld
Researcher
Contact

Risks for seabirds

Using ship-based counts by bird researchers, Wageningen Marine Research contributes to mapping the populations, area use, migration flows and flight patterns of birds at sea. Comparisons are also made between area use before and after the construction of a wind farm.

Do birds dare to forage for food in a wind farm?

In addition, we use visual observations to map the behaviour of specific bird species such as guillemots and cormorants in and around wind farms. The underlying questions are: do they stay in the wind farm or do they avoid it? How do birds forage within the wind farm and on what species? It is also being investigated whether habituation occurs over time and whether species which used to exhibit avoidance behaviour now dare to enter a wind farm.

Our research

Developments in populations, area use, migration and flight patterns of birds in Dutch waters
Cumulative effects of (planned) wind farms on bird populations, including interpretation through modelling research
Effects of mitigation measures and innovations to protect birds
Behaviour of bird species in wind farms including foraging behaviour; which species are affected and is there a case of habituation or not
Which locations are suitable and less suitable for wind farms