New Study Looks at Impact of Offshore Wind on Coastal Ecosystems

Offshore wind farms can have an impact on the marine ecosystems they are built in and upon, a new study has found, but much more research is needed to understand those impacts and how to best plan for them.

Researchers from the Hereon Institute of Coastal Systems — Analysis and Modeling – in Germany looked at the potential impacts of the planned expansion of offshore wind in the North Sea that will be required to meet the European Green Deal goal of achieving carbon neutrality by 2050. 

“Our results show that the extensive expansion of offshore wind farms will have a significant impact on the structuring of marine coastal ecosystems,” study co-author Ute Daewel said in a press release. “We need to better understand these impacts quickly and also take them into account in the management of coastal ecosystems.” 

The North Sea has become a “global hotspot for offshore wind energy production” because of its shallow sandbanks and steady wind supply, the study authors wrote in Communications Earth & Environment last week. As of 2021, there was 28-gigawatts (GW) worth of offshore wind capacity installed there, and that is slated to increase to 212 GW by 2050. 

The study authors modeled what would happen if all capacity announced as of 2015 were installed, which amounted to 120 GW by 2037. Specifically, they looked at the impact of the atmospheric disturbance caused by the wind turbines on the water below and the building blocks of the marine food web: nutrients, phytoplankton, zooplankton and sediment biomass, according to the press release.

Essentially, because the air vortices created by the turbines can impact the movement of the water below them, this also alters the movement of smaller ocean organisms and changes where they are placed. In some areas, for example, biogenic carbon in ocean sediment could increase by 10 percent, reducing oxygen concentration. In other areas, the changes could increase or reduce the production of phytoplankton by 10 percent in either direction throughout the southern North Sea. 

Changes in these primary food sources could impact larger animals as well. 

“The southern North Sea is well-known for supporting a diversity of marine fauna, and especially the near-coastal areas are nursery grounds for many economically relevant fish stocks,” the study authors wrote. 

If the food of some of these fish relocates, it could harm them when they are growing and used to having specific conditions in a specific area. 

“Understanding these changes is pivotal for successful future fisheries management in the North Sea and could influence the identification and implementation of marine protected areas,” the study authors wrote. 

In general, the study points to the need for more research into the environmental impacts of offshore wind farms, which remain poorly understood. A Bangor University study published in September called for a deeper investigation into how floating offshore installations in deeper waters would impact ocean ecosystems as they create new turbulence when tides push against a barrier that wasn’t there before.

“Turbulent mixing determines the timing and rate of the food supply on which marine ecosystem and key species rely. Flow past deep water wind farms will introduce ‘anthropogenic’ or man-made turbulence, and increase mixing. This fundamental change could lead to significant regional impacts, which must be assessed,” study co-author Dr. Ben Lincoln of Bangor University said in a press release at the time. “However, impacts are not necessarily negative, with the potential to enhance productivity and offset the impact of increasing stratification due to climate change.” It should be noted that the alternative to offshore wind–offshore oil and gas drilling–has established devastating impacts on marine ecosystems. BP’s Deepwater Horizon oil spill of 2010 killed up to 800,000 birds, caused more than three-quarters of bottlenose dolphin pregnancies in the impacted areas to fail and severely reduced biodiversity in the places closest to the spill. The climate crisis is also a major threat to marine life and ecosystems–warming of two degrees Celsius would kill off 99 percent of tropical coral reefs.