Benthos
The bottom of the Dutch North Sea is characterized by sand waves, sand banks and channels covered with sand and silt. Locally there are also gravel banks or areas with boulders, as a reminder of the last ice age. In addition to fish, many different bottom animals, called benthos, live on the bottom of the North Sea, including starfish, worms, shellfish, snails and crustaceans. The construction and presence of wind farms in the North Sea affect the area and the benthic animals and plants. Wozep conducts research into the effects on benthos and subsequently into the changes in the entire ecosystem.
The North Sea is a relatively shallow sea, with the Dutch part of the North Sea having an average depth of about 30 meters. It is an area that is intensively used by many functions, including fishing, shipping, oil and gas extraction, sand extraction, recreation and wind farms.
The construction of a wind farm will change the area somewhat. The turbine piles and the erosion protection layer introduce hard substrate into a sandy environment. In addition, the area is excluded from other forms of use, but passage and shared use have recently been permitted for some wind farms.
The change from mainly soft substrate benthos to a mix with also hard substrate benthos changes the use of primary production across the water column, which can have effects on the availability of algae outside the park. In addition, benthos provides food for higher trophic levels. How these changes impact the benthos communities and subsequently the entire ecosystem is part of the Wozep research.
To gain more insight into the development of the benthic community within wind farms, research has been carried out in the Princes Amalia Wind Farm (PAWP) since 2003 to map the benthic developments on the soft substrate (sandy bottom) (surveys were carried out in 2003 , 2012, 2013, 2017 and 2022). In addition, soft substrate benthos research has also been started with regard to newer wind farms further offshore.
Research into the development of hard substrate (monopile and erosion protection) is a lot more complicated. Due to amended legislation, which no longer allows divers to be used around offshore installations (including wind turbines), we are looking at alternative methods to do this.
For example, Wozep has had a tool developed that, mounted on an underwater robot, can take samples from the seabed. An initial test with the tool was successful. The Wozep/MONS team is investigating whether scaling up this method is possible in several offshore wind farms and on wind turbine foundations. The collected data will be used to investigate how much growth of marine fauna you see in offshore wind farms and whether this has an effect on the North Sea ecosystem.