They are a good renewable energy alternative. But there is a small problem. Wind farms affect the oceans. They can strongly influence marine primary production. Also on oxygen levels in and around the surrounding areas. These are the conclusions of scientists published in the journal Communications Earth & Environment.
Different wind conditions and currents, more precipitation and a changing surface climate. The effects of offshore wind farms in the North Sea are diverse. And they have not yet been fully investigated. Some of them are already occurring, others are still to be expected: wind farms are still expanding.
Moving the waters
Turbulent wakes are air vortices caused by wind turbines. They were shown to change the flow and stratification of the water beneath them. But the climate just above the sea surface is also permanently changing.
A study, led by Dr. Ute Daewel, confirms that these impacts lead to an altered spatial distribution of marine ecosystem components. This includes the distribution of nutrients, phyto- and zooplankton. Also the biomass in the sediment, the food base of many bottom-dwelling organisms.
In the model study, the team assumed large-scale offshore wind farms planned in the North Sea. In deeper marine areas, biogenic carbon in the sediment would increase locally by 10%. Oxygen concentration could decrease to a large extent.
Wind shifts change the primary production of phytoplankton by up to 10%. And it has consequences for the distribution of zooplankton, the food base of many fish species. Early life stages of fish depend on timely access to zooplankton.
Ripple effect
A spatial and temporal restructuring of zooplankton distribution can influence these process chains. And affect the amount of fish available. Perhaps it would be a small change in primary production. But it would have a lasting impact on the entire food web in the southern North Sea.
“Wind farms affect the oceans. Their expansion will impact the structuring of marine coastal ecosystems. We need to better understand these impacts quickly and also take them into account in the management of coastal ecosystems”, concludes Ute Daewel in a statement.
