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1 Introduction A review of potential negative and positive impacts of offshore wind farms (OWF) on the marine environment was conducted in 2009, and the results are presented below. Statements and conclusions are not necessarily based on consensus, but rather aim to reflect the median views of the authors. The analysis treats animal groups as representing a cross section of species. Systems and ecological responses may, however, differ significantly between regions and localities. Large data gaps exist, and effects are species-, site-, and season specific. Also, acceptable levels of disturbances will depend on the local/regional conservation status of species or habitats in question. Most effects treated in this review are assessed on spatial, temporal scales, as well as in terms of the estimated degree of severity or benefit for organisms within a wind farm area, according to the legend below. Key: Temporal and spatial dimensions, as well as the severity/benefit of effects on species assemblages are noted in the text according to categories as defined below (in bold italic text). Where appropriate, conclusions provide ‘certainty’ scores, indicating the level of certainty of understanding provided by current research: Temporal • Short term: through construction phase • Long term: through operational phase • Permanent: effects persist beyond the operational and decommissioning phases. Spatial • Very local: within 10 m from wind turbines • Local: within 100 m from wind turbine • Broad: within 1000 m from wind turbine • Very broad: > 1000 m from wind turbine Estimated degree of severity (-) or benefit (+) of impacts for species assemblages within the wind farm area are categorised as: • Small: impacts should not influence or have small impacts on size or structure of assemblage. • Moderate: impacts could moderately influence species assemblages, generally or for particular species • Large: impacts could significantly influence size or structure of species assemblages, generally or for particular species. 34 GREENING BLUE ENERGY - Identifying and managing biodiversity risks and opportunities of offshore renewable energy Certainty 1 = Literature consists of scientifically founded speculations 2 = Research is in its infancy and inconclusive 3 = Available literature provides a fair basis for assessments 4 = Available literature provides a good basis for assessments 5 = Evidence base is relatively solid 2 Main types of sea areas likely to be used for offshore wind power Current technologies, including monopiles, tripods and gravity foundations (See Box 1 in Chapter 4 of the main document) limit offshore, non-floating wind turbines to coastal areas not deeper than 30 meters, with some exceptions (e.g. Zhixin 2009). Seabeds consisting of muddy sand, sand or gravel beds with only scattered boulders are preferred for technical and economic reasons. Exploited areas are obviously exposed to strong wind forces. Thus, the substrate is frequently turned over during storms and communities may be dominated by opportunistic algae and animal. However offshore banks that are technically suit-
able for wind power development can provide a refuge for species that have been excluded by pollution, eutrophication and anthropogenic development further inshore. Infaunal assemblages that are important sources of food for birds and fish usually dominate the seabed in these habitats, in both temperate and tropical regions. Such areas provide habitats for feeding, resting, and may be especially important as nursery habitats for mammals and seabirds. Adjacent areas to wind farms may include a range of habitats, such as rocky or coral reefs, sandy shores, kelp forests, etc. Thus, the disturbance caused by construction and operations of the turbines may not be limited to the wind farm area itself, and risk assessments for a variety of habitats are necessary. 3 Impacts of the addition of hard bottom habitats 3.1. Sessile organisms Whenever a new material is submerged in the sea it will become colonised by marine organisms. Microbial colonisation occurs within hours and will be followed over weeks to months by settlement of macrobiota (e.g. Svane & Petersen 2001). The initial phases of colonisation are predominantly influenced by physical conditions and are relatively predictable (Wahl 1989). The macrobiotic assemblage that develops on a structure can be difficult to predict and is strongly influenced by availability of settling stages and subsequent biological interactions (Keough 1983; Rodriguez et al. 1993; Santelices 1990). However, in the longer term, the season of submersion tends to have no significant influence on the sessile community (e.g. Qvarfordt et al. 2006, Langhamer et al. 2009). Further, the position of the structure in the water column may be more important than age or type of the substrate (Connell 2000, Knott et al. 2004, Perkol-Finkel et al. 2006). Typical “pier piling assemblages” (Davis et al. 1982), dominated by filter feeding invertebrate animals generally develop on wind turbines. In post construction surveys of wind turbines in Denmark Sweden, and U.K. two principal assemblages have been observed; either dominance by barnacles and blue mussels (Mytilus edulis), in true marine areas together with predatory starfish, or dominance by anemones, hydroids and solitary sea squirts (Dong <strong>Energy</strong> et al. 2006, Linley et al. 2007, Wilhelmsson & Malm 2008, Maar et al. 2009). Wind turbines may offer a particularly favourable substrate for blue mussels (Wilhelmsson et al. 2006, Maar et al. 2009). Turbines can facilitate 10 times higher biomass of blue mussels than on bridge pilings (Maar et al. 2009). Each turbine may support 1-2 metric tonnes of mussels, and double the biomass of filter feeders in a wind farm area as a whole compared to before construction (Maar et al. 2009). The mussel matrices on the turbines provide habitat and food for small crustaceans, which in turn constitute prey for fish and other predators (e.g. Zander 1988, Norling & Kautsky 2008). The structural complexity provided by mussel beds promotes biodiversity of macroinvertebrates and the waste material they produce can enhance the abundance of other species (e.g. Ragnarsson & Raffaelli 1999, Norling & Kautsky 2007, 2008). Mussels can also cause a shift from a primary producer and grazer dominated food chain towards a detritus feeding community (Norling & Kautsky 2007, 2008). From an operational perspective fouling of the wind turbine tower is detrimental, adding to the weight and drag from water movement and it may also facilitate corrosion. Antifouling paints are generally not used on wind turbines, however cleaning of the turbines creates a periodic (~ every 2 years) disturbance/removal of assemblages. Studies on wind power turbines, bridge pilings and buoys, however, suggest that the biomass of dominating organisms on these vertically oriented structures do not increase notably with time after 1-2 years of submergence (Qvarfordt 2006, Wilhelmsson & Malm 2008, Langhamer et al. 2009). This is a result of counteraction of colonisation/growth by dislodgment of mussels due to gravity and wave action, as well as to food and space limitations. Similar effects could be expected in tropical water (e.g. Wilhelmsson et al. 1998, Svane & Petersen 2001). Unless repainting is necessary, cleaning of turbines may therefore not be sufficiently beneficial to justify the costs and habitat disturbance involved. Trawling, which is one of the most severe threats to the marine environment (e.g. Thrush & Dayton 2002), including both fish and benthic assemblages, Identifying and managing biodiversity risks and opportunities of offshore renewable energy - GREENING BLUE ENERGY 35
Page 1 and 2: Greening Blue Energy: Identifying a
Page 3: Greening Blue Energy: Identifying a
Page 6 and 7: About the Organisations IUCN IUCN,
Page 8 and 9: Acknowledgements The IUCN Global Ma
Page 11 and 12: 1 Introduction 1.1 Background Incre
Page 13: considerations of other marine user
Page 16 and 17: Offshore wind energy overview Natio
Page 19 and 20: 3 Impact assessment This section pr
Page 21: 3.3.1 European legislation The EU E
Page 24 and 25: Key environmental issues Level of c
Page 26 and 27: Marine impacts 4.2 Managing impacts
Page 28 and 29: Marine impacts Foundation Types (co
Page 30 and 31: Marine impacts Fishing vessel leavi
Page 32 and 33: Marine impacts Annexe 1 - see Secti
Page 34 and 35: Marine impacts a wind farm has effe
Page 36 and 37: Marine impacts Figure 4: A summary
Page 39 and 40: 5 Conclusions and recommendations 5
Page 41: 6 Additional resources While the ne
Page 46 and 47: will be prohibited inside energy pa
Page 48 and 49: 2002). Vertically oriented structur
Page 50 and 51: it is certain that the wind turbine
Page 52 and 53: ous nature may, however, only arise
Page 54 and 55: the whole wind farm area itself (Ma
Page 56 and 57: adically among species (e.g. Thomse
Page 58 and 59: struction activities at multiple wi
Page 60 and 61: particular area, scientists recomme
Page 62 and 63: 7.8 Noise and avoidance by sea turt
Page 64 and 65: species such as elasmobranches and
Page 66 and 67: may fly at altitudes lower than 20
Page 68 and 69: should be pointed out that the repo
Page 70 and 71: depending on the species (Dierschke
Page 73 and 74: Annexe 2 Legislation Contents 1 EIA
Page 75 and 76: 2 Strategic Environmental Assessmen
Page 77 and 78: 3 Marine Strategy Framework Directi
Page 79 and 80: Annexe 3 Brief on Wave, Tidal and C
Page 81 and 82: Figure 2: Example of wave converter
Page 83 and 84: impact of noise emissions on marine
Page 85 and 86: Pelc and Fujita (2002) raised conce
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Page 90 and 91: Bio/consult A/S. (2000a). Horns Rev
Page 92 and 93: Edren, S.M.E., Teilman, J., Dietz,
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Wind Farm construction in harbour p
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Aquatic Sciences. 63:2603-2607 Lewi
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Peters, R.C., Lonneke, B.M., Bretsc
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cause versus effect. Oceanography a
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påverkas av ljud från vindkraft t
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