The large-scale implementation of offshore energy harvesting in shallow coastal seas will likely have ecological consequences. Much attention has been paid to impacts of windmills on birds, but underwater effects of windfarms and offshore solar have received less attention. We summarize known or expected effects in this contribution, and discuss possibilities for mitigating effects.   Windfarms extract energy from the wind and consequently modify the air-water interaction. In addition, energy is extracted from the tidal motion of the water and dissipated as turbulence. Both interactions change vertical mixing of the water column, affecting the distribution of dissolved and particulate matter. It is expected that, at least locally, this will lead to changes in primary production. Changes in bottom shear stress lead to altered suspended matter dynamics. Offshore solar primarily affects light climate, but may also interferes with physical effects of windfarms.   Energy farms change the physical habitat characteristics of shallow seas, by introducing hard substrate in a soft-sediment environment. The transport of energy as electric current or, in the future, as hydrogen, may entail further habitat modifications. Large energy hubs and extensive cable and pipeline networks extend the physical impacts to sensitive coastal areas. This will change faunal communities and affect the balance between pelagic and benthic grazers. Indirectly, these changes may affect the food web in the sea and the biological factors responsible for pelagic-benthic exchange of mineral and organic matter.

Tutorial/Invited: Invited, Tutorial

Primary Presenter: Peter Herman, Deltares (peter.herman@deltares.nl)

Authors:

Peter Herman, Deltares  (peter.herman@deltares.nl)

Luca van Duren, Deltares  (luca.vanduren@deltares.nl)

Lauriane Vilmin, Deltares  (lauriane.vilmin@deltares.nl)