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The pelagic ecosystem

Thomas Dahlgren talks in this video about the impact offshore wind has in the pelagic ecosystem.

Large offshore wind farms where early on suggested to have an impact on upper ocean circulation through changes in the Ekman transport of water caused by the windfarms lee effect relative to surrounding wind speeds. The turbine foundation structures will also cause increased mixing through turbulence from water moving through the wind farm in e.g. tidal currents.

This upper ocean mixing may provide micro algae with more nutrients and hence increase the primary production. But stratification, nutrient status and other factors limiting primary production is different for different seas and times of the year, and the effects are not yet fully understood.

Learning outcome.

After having watched this video, you should know:

  • OWE can reduce upper ocean stratification by increased mixing
  • There are two processes: The lee effect and increased turbulence
  • This can lead to increased primary productivity
  • The effects are most likely very site specific due to the natural state of stratification and nutrient levels (eg big difference between the Baltic Sea and the North Sea

Suggested literature

Some references may require a user account for the journal.

On the influence of large wind farms on the upper ocean circulation. Journal of Marine Systems 74, 585–591.

Pelagic effects of offshore wind farm foundations in the stratified North Sea. Progress in Oceanography 156, 154–173.

Emergence of Large-Scale Hydrodynamic Structures Due to Atmospheric Offshore Wind Farm Wakes. Front. Mar. Sci. 9, 818501.

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Introduction to Offshore Wind Energy

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