Abstract
Marine renewable technologies have rapidly been developing over the past decade. Wave power is one of the renewable sources and has the potential securing the renewable electricity production. However, all renewable energy extraction affects the environment in some way and for a true sustainable energy generation, environmental effects need to be investigated. Beside uncertain effects from the technologies to habitats or organisms e.g., collision risks, electromagnetic fields, noise, past studies have also shown benefits on diversity, size and abundance of species around marine renewable technologies as a result of habitat creation by the devices and fishery exclusion in designated offshore park areas.
This thesis deals with environmental effects from heaving point-absorber wave energy converters developed at Uppsala University and deployed on the Swedish west coast at the Lysekil research site and the Sotenäs Project wave power park over a period of four years. The scope was the investigation of artificial reef effects from wave power foundations on local mobile, mega and macrofauna during visual inspections using scuba diving on the first hand. On the second hand, the effects from the incidental no-take zone on decapods and two sea pen species were investigated applying cage fishing and ROV seabed surveys. A third focus was on environmental monitoring around MRE sites and monitoring of MRE installations, both in an experimental and theoretical approach.
In the Lysekil research site, the results highlight that abundance and diversity can be enhanced locally around wave power foundations compared to control areas. The abundance and size of decapods were not significantly different within the wave power park and up to a distance of 360 m outside of it. In the Sotenäs Project wave power park a positive effect on Nephrops norvegicus size and burrow density but not on abundance was found on a scale of up to 1230 m. Sea pen abundance was enhanced inside the wave power park. However, interannual variation was strong.
In conclusion, wave power foundations can influence abundance and diversity of marine organisms around foundations on a very local scale (meters). With the methods in this study, the investigations did not reveal strong effects on the abundance and size of decapods on a larger scale up to 1230 m away from foundations as a result of the no-take zone. However, a focus should be put on a further development of environmental monitoring routines around MRE sites and their evaluation.