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Colonisation of fish and crabs of wave energy foundations and the effects of manufactured holes- a field experiment
Stockholm University, Faculty of Science, Department of Zoology.
2009 (English)In: Marine Environmental Research, ISSN 0141-1136, Vol. 68, no 4, 151-157 p.Article in journal (Refereed) Published
Abstract [en]

Several Western European countries are planning for a significant development of offshore renewable energy along the European Atlantic Ocean coast, including many thousands of wave energy devices and wind turbines. There is an increasing interest in articulating the added values of the creation of artificial hard bottom habitats through the construction of offshore renewable energy devices, for the benefit of fisheries management and conservation. The Lysekil Project is a test park for wave power located about 100 km north of Gothenburg at the Swedish west coast. A wave energy device consists of a linear wave power generator attached to a foundation on the seabed, and connected by a wire to a buoy at the surface. Our field experiment examined the function of wave energy foundations as artificial reefs. In addition, potentials for enhancing the abundance of associated fish and crustaceans through manufactured holes of the foundations were also investigated. Assemblages of mobile organisms were examined by visual censuses in July and August 2007, 3 months after deployment of the foundations. Results generally show low densities of mobile organisms, but a significantly higher abundance of fish and crabs on the foundations compared to surrounding soft bottoms. Further, while fish numbers were not influenced by increased habitat complexity (holes), it had a significantly positive effect on quantities of edible crab (Cancer pagurus), on average leading to an almost five-fold increase in densities of this species. Densities of spiny starfish (Marthasterias glacialis) were negatively affected by the presence of holes, potentially due to increased predator abundance (e.g. C. pagurus). These results suggest a species-specific response to enhanced habitat complexity.

Place, publisher, year, edition, pages
2009. Vol. 68, no 4, 151-157 p.
Keyword [en]
Artificial reefs; Coastal zone management; Disturbance; Fisheries; Habitat complexity; Habitat enhancement; Wave power
URN: urn:nbn:se:su:diva-30885DOI: 10.1016/j.marenvres.2009.06.003ISI: 000269242100001OAI: diva2:274679
Available from: 2009-10-30 Created: 2009-10-30 Last updated: 2009-11-06Bibliographically approved
In thesis
1. Aspects of offshore renewable energy and the alterations of marine habitats
Open this publication in new window or tab >>Aspects of offshore renewable energy and the alterations of marine habitats
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Several Western European countries are planning for a massive offshore renewable energy (i.e. wind and wave energy) development (ORED) along the European Atlantic coast and in the Baltic Sea. Acknowledging the scale of ORED, there is an increasing interest in the opportunities offered by the fishery closures and the addition of artificial hard substrata. This is in tandem with uncertainties on positive and negative effects on benthic assemblages and specific species of this large-scale deployment of artificial reefs.

This thesis focuses on the artificial reef effects of ORED, dealing with benthic assemblages on and in the vicinity of wind- and wave power foundations. Field surveys within offshore wind- and wave farms as well as targeted field experiments were conducted. Results suggest that wind- and wave power foundations can positively affect local abundances and diversity of several species of fish and decapods. Reef profile up to 1 m above the seabed may enhance benthic fish numbers. Structural complexity in the form of single-entrance holes positively affected numbers of edible crab (Cancer pagurus), but no effect on fish was shown. Enhanced structural complexity may, moreover, adversely affect abundances of some species through an induced predation pressure. Micro-habitat use by fish and lobsters (Homarus gammarus) encountered was described, and preferences of the edible crab were shown.

Filtrating organisms (i.e. blue mussels Mytilus spp. and barnacles Balanus spp.) seem to be particularly favoured by the conditions on offshore energy installations. The material and orientation of the substrate influenced colonisation patterns of epibiota. Moreover, wind turbines may alter the habitat composition on adjacent seabeds.

ORED could induce local ecological changes and put areas and species of conservation interest at risk. If well planned and co-ordinated, on the other hand, ORED could even be beneficial to the subsurface marine environment in several aspects.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2009. 56 p.
renewable energy, biodiversity, wave power, wind power, disturbance, fish, fouling organisms, artificial reefs
Research subject
Animal Ecology
urn:nbn:se:su:diva-31157 (URN)978-91-7155-970-8 (ISBN)
Public defence
2009-12-11, hörsal 11, hus F, Universitetsvägen 10 F, Stockholm, 10:00 (English)
Available from: 2009-11-19 Created: 2009-11-06 Last updated: 2014-10-28Bibliographically approved

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