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Aspects of offshore renewable energy and the alterations of marine habitats
Stockholm University, Faculty of Science, Department of Zoology.
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.
Keyword [en]
renewable energy, biodiversity, wave power, wind power, disturbance, fish, fouling organisms, artificial reefs
Research subject
Animal Ecology
Identifiers
URN: urn:nbn:se:su:diva-31157ISBN: 978-91-7155-970-8 (print)OAI: oai:DiVA.org:su-31157DiVA: diva2:275621
Public defence
2009-12-11, hörsal 11, hus F, Universitetsvägen 10 F, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2009-11-19 Created: 2009-11-06 Last updated: 2014-10-28Bibliographically approved
List of papers
1. Epibenthic colonization of concrete and steel pilingsin a cold-temperate embayment: a feld experiment
Open this publication in new window or tab >>Epibenthic colonization of concrete and steel pilingsin a cold-temperate embayment: a feld experiment
2009 (English)In: Helgoland Marine Research, ISSN 1438-387X, E-ISSN 1438-3888, Vol. 63, no 3, 249-260 p.Article in journal (Refereed) Published
Abstract [en]

With large-scale development of offshore wind farms, vertical structures are becoming more common in open water areas. To examine how vertical structures of different materials may be colonized by epibenthic organisms, an experiment was carried out using steel and concrete pilings constructed to resemble those commonly used in wind farm constructions as well as in bridges, jetties and oil platforms. The early recruitment and succession of the epibenthic communities were sampled once a month for the first 5 months and then again after 1 year. Further, the fish assemblages associated with the pillars were sampled and compared to natural areas. The main epibenthic species groups, in terms of coverage, diVered between the two materials at five out of six sampling occasions. Dominant organisms on steel pillars were the barnacle Balanus improvisus,the calcareous tubeworm Pomatoceros triqueter and the tunicate Ciona intestinalis. On the concrete pillars, the hydroid Laomedea sp. and the tunicates Corella parallelogramma and Ascidiella spp. dominated. However, there was no different in coverage at different heights on the pillars or in biomass and species abundance at different directions (north-east or south-west) 5 months after submergence. Fish showed overall higher abundances and species numbers on the pillars (but no difference between steel and concrete)compared to the surrounding soft bottom habitats but not compared to natural vertical rock walls. Two species were attracted to the pillars, indicating a reef effect; Gobiusculus flavescens and Ctenolabrus rupestris. The bottom-dwelling gobies, Pomatoschistus spp., did not show such preferences.

Keyword
Artifcial reef, Disturbance, Habitat structure, Reef effect, Renwable energy, Tunicates
National Category
Ecology
Research subject
Animal Ecology
Identifiers
urn:nbn:se:su:diva-30684 (URN)10.1007/s10152-009-0156-9 (DOI)000269013800008 ()
Projects
Downvind
Available from: 2009-10-22 Created: 2009-10-22 Last updated: 2017-12-12Bibliographically approved
2. Colonisation of fish and crabs of wave energy foundations and the effects of manufactured holes- a field experiment
Open this publication in new window or tab >>Colonisation of fish and crabs of wave energy foundations and the effects of manufactured holes- a field experiment
2009 (English)In: Marine Environmental Research, ISSN 0141-1136, E-ISSN 1879-0291, 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.

Keyword
Artificial reefs; Coastal zone management; Disturbance; Fisheries; Habitat complexity; Habitat enhancement; Wave power
Identifiers
urn:nbn:se:su:diva-30885 (URN)10.1016/j.marenvres.2009.06.003 (DOI)000269242100001 ()
Available from: 2009-10-30 Created: 2009-10-30 Last updated: 2017-12-12Bibliographically approved
3. Artificial reef effect and fouling impacts on offshore wave power foundations and buoys- a pilot study
Open this publication in new window or tab >>Artificial reef effect and fouling impacts on offshore wave power foundations and buoys- a pilot study
2009 (English)In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 82, no 3, 426-432 p.Article in journal (Refereed) Published
Abstract [en]

Little is known about the effects of offshore energy installations on the marine environment, and further research could assist in minimizing environmental risks as well as in enhancing potential positive effects on the marine environment. While biofouling on marine energy conversion devices on one hand has the potential to be an engineering concern, these structures can also affect biodiversity by functioning as artificial reefs. The Lysekil Project is a test park for wave power located at the Swedish west coast. Here, buoys acting as point absorbers on the surface are connected to generators anchored on concrete foundations on the seabed. In this study we investigated the colonisation of foundations by invertebrates and fish, as well as fouling assemblages on buoys. We examined the influence of surface orientation of the wave power foundations on epibenthic colonisation, and made observations of habitat use by fish and crustaceans during three years of submergence. We also examined fouling assemblages on buoys and calculated the effects of biofouling on the energy absorption of the wave power buoys. On foundations we demonstrated a succession in colonisation over time with a higher degree of coverage on vertical surfaces. Buoys were dominated by the blue mussel Mytilus edulis. Calculations indicated that biofouling have no significant effect in the energy absorption on a buoy working as a point absorber. This study is the first structured investigation on marine organisms associated with wave power devices.

Keyword
biodiversity; benthos; fish; shellfish; renewable energy; wave power; Sweden
Identifiers
urn:nbn:se:su:diva-26745 (URN)10.1016/j.ecss.2009.02.009 (DOI)000265573400007 ()
Available from: 2009-04-09 Created: 2009-04-09 Last updated: 2017-12-13Bibliographically approved
4. Fouling assemblages on offshore wind power plants and adjacent substrata
Open this publication in new window or tab >>Fouling assemblages on offshore wind power plants and adjacent substrata
2008 (English)In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 79, no 3, 459-466 p.Article in journal (Refereed) Published
Abstract [en]

A significant expansion of offshore wind power is expected in the near future, with thousands of turbines in coastal waters, and various aspects of how this may influence the coastal ecology including disturbance effects from noise, shadows, electromagnetic fields, and changed hydrological conditions are accordingly of concern. Further, wind power plants constitute habitats for a number of organisms, and may locally alter assemblage composition and biomass of invertebrates, algae and fish. In this study, fouling assemblages on offshore wind turbines were compared to adjacent hard substrate. Influences of the structures on the seabed were also investigated. The turbines differed significantly from adjacent boulders in terms of assemblage composition of epibiota and motile invertebrates. Species number and Shannon-Wiener diversity were, also, significantly lower on the wind power plants. It was also indicated that the turbines might have affected assemblages of invertebrates and algae on adjacent boulders. Off shore wind power plant offer atypical substrates for fouling assemblages in terms of orientation, depth range, structure, and surface texture. Some potential ecological implications of the addition of these non-natural habitats for coastal ecology are discussed.

Keyword
artificial reefs, Baltic Sea, coastal zone management, disturbance, fouling organisms, wind power
Identifiers
urn:nbn:se:su:diva-15697 (URN)10.1016/j.ecss.2008.04.020 (DOI)000259731900012 ()
Available from: 2008-12-08 Created: 2008-12-08 Last updated: 2017-12-13Bibliographically approved
5. The influence of offshore wind power on demersal fish
Open this publication in new window or tab >>The influence of offshore wind power on demersal fish
2006 (English)In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 63, no 5, 775-784 p.Article in journal (Refereed) Published
Abstract [en]

A significant expansion of offshore windpower is expected in northwestern Europe in the near future. Little is known about the impacts it may have on the marine environment. Here, we investigate the potential for wind turbines to function as artificial reefs and fish aggregation devices (FADs), i.e. whether they would locally increase fish densities or alter fish assemblages. Fish communities and habitat composition were investigated using visual transects at two windpower farms off the southeastern coast of Sweden, central Baltic Sea. Fish abundance was greater in the vicinity of the turbines than in surrounding areas, while species richness and Shannon–Wiener diversity (H') were similar. On the monopiles of the turbines, fish community structure was different, and total fish abundance was greater, while species richness and diversity (H') were lower than on the surrounding seabed. Blue mussels and barnacles covered most of the submerged parts of the turbines. On the seabed, more blue mussels and a lesser cover of red algae were recorded around the power plants than elsewhere. Results from this study suggest that offshore windfarms may function as combined artificial reefs and fish aggregation devices for small demersal fish.

Keyword
artificial reefs, biodiversity, fishery, Gobidae, human disturbance, marine protected area, wind power
Identifiers
urn:nbn:se:su:diva-30886 (URN)10.1016/j.icesjms.2006.02.001 (DOI)
Available from: 2009-10-30 Created: 2009-10-30 Last updated: 2017-12-12Bibliographically approved
6. Effects of high-relief structures on cold-temperate fish assemblages: a field experiment
Open this publication in new window or tab >>Effects of high-relief structures on cold-temperate fish assemblages: a field experiment
2006 (English)In: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 2, no 2, 136-147 p.Article in journal (Refereed) Published
Abstract [en]

High-relief structures may influence the abundance and diversity of reef-associated fish. We conducted a field experiment to investigate whether the presence of vertical structures (PVC pipes) affects fish communities on artificial reefs. The effect of the height of the structures (1 and 3 m) was also tested. Furthermore, the effects on fish of placing artificial reefs on otherwise featureless bottoms were quantified. Algal and macro-invertebrate colonization of the reefs was also recorded. The experiment was carried out on the west coast of Sweden over a period of 1 year. The vertical structures had a positive effect on fish abundance but not on diversity. The height of the structures did not, however, influence the fish communities. Natural as well as urban vertical structures on the seafloor could have a positive effect on local fish abundance. The positive effects of artificial reefs on total fish abundance and diversity were immediate. Of the 10 species recorded, two, the black goby Gobius niger and the goldsinny wrasse Ctenolabrus rupestris , dominated over the whole survey period. There were significant temporal differences in fish abundance, and diversity increased with time.

Identifiers
urn:nbn:se:su:diva-30887 (URN)10.1080/17451000600684359 (DOI)
Available from: 2009-10-30 Created: 2009-10-30 Last updated: 2017-12-12Bibliographically approved

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