23 research outputs found
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Effects of Altered Habitats and Fishing Practices in Wind and Wave Farms
Offshore renewable energy development (ORED) could induce local ecological changes, negatively affecting species of conservation interest. If well planned and coordinated, on the other hand, ORED could be beneficial to the marine environment in the region of device deployment in several respects.
Because of the current scale and pace of offshore renewable energy development, interest is growing in the opportunities offered by the changes in fishing patterns that could result. Trawling, one of the most severe threats to the marine environment, particularly to fish and benthic invertebrate assemblages, will be prohibited or limited inside wind and wave farms. Areas of several square kilometres may therefore, in some important respects, resemble Marine Protected Areas; for areas that were previously trawled this exclusion could lead to average increases in biomass of motile organisms. Primary data from wind and wave farms are still scarce, but results to date from surveys targeting fish assemblages within offshore wind farms in Denmark, the Netherlands, and Sweden basically indicate either increased abundance of some fish species (e.g., sand eels (Ammodytidae), cod (Gadus morhua), whiting (Merlangius merlangus), sole (Solea solea)) or no effect compared to conditions before construction of the wind farm. Effects are likely to be most prominent for species that had been heavily exploited in the area prior to the wind or wave farm establishment. It is believed that a relatively large area of exclusion is required to enhance biodiversity and generate spill-over effects.
Construction and deployment of artificial reefs (AR) in coastal waters is practiced worldwide to manage fisheries, mitigate damage to the environment, protect (i.e., from trawling) and facilitate the rehabilitation of certain habitats (e.g., spawning sites) or water bodies, or to increase the recreational value of an area (e.g., by providing opportunities for recreational diving and fishing). Unless animals are deterred by potential disturbances, such as noise, maintenance work, and electromagnetic fields from turbines, it is reasonable to expect offshore wind energy structures, and also foundations of some types of wave energy devices, to function as artificial reef modules and enhance local abundance of marine organisms, including commercially important fish and crustaceans. However, taxon- and age-specific responses of fishes to ARs vary greatly with AR design and position as well as by region and latitude. It can therefore be difficult to predict the structure of fish and crustacean assemblages associated with the submerged parts of wind and wave energy devices, as well as the radius of influence. Nevertheless, relatively recent studies targeting the potential for wind turbines and wave energy foundations to aggregate fish and motile invertebrates in Sweden, the Netherlands, Belgium, and Denmark suggest that densities of a number of fish and decapod species increase with proximity to these structures.
Another category of artificial habitat is a Fish Aggregation Device (FAD), a floating structure deliberately placed on the surface or suspended in the water column to attract fish and enhance fishing efficiency. FADs are widely used in Asia and the western Indian Ocean. It has been suggested that floating offshore energy devices may function as FADs for pelagic fish, which could provide additional opportunities for fisheries management.
Both ARs and FADs can have negative environmental and social effects if not properly planned and/or used. If ARs only aggregate fish from surrounding areas and do not contribute to added production, enhanced fishing efficiency in the AR area may aggravate overfishing if the new circumstances are not managed with caution. Similarly, increasing catchability, the main purpose of an FAD, may exacerbate the problem of overfishing on commercial species that are already at risk. ARs can also give rise to conflicts over user rights among fisher groups, and between recreational divers and fishers.
Further, densities of benthic prey items have been shown to decrease with proximity to ARs due to predation by fish residing on the structures. FADs have been suggested as potential “ecological traps,” meaning that their presence could lure fish into remaining near the structures under non-optimal local feeding conditions, affecting physical condition and growth. Artificial structures may also provide habitats suitable for establishment of non-indigenous species; deployment of clusters of artificial structures may facilitate the establishment of new taxa in the recipient region by providing “beach heads” and stepping-stones. Non-indigenous sessile invertebrates have already been recorded at wind farms in the North Sea and the Baltic Sea.
A range of design and location factors may influence the fish community structure on artificial reefs, such as height, size, inclination, protuberance, surface structure, void space and number of interior hollows, shade effects, distance between modules, isolation, and composition of the surrounding seabed. Research is underway to evaluate species-specific habitat preferences in the design of offshore energy foundations to optimize biomass of desired species, or alternatively, minimize artificial reef effects where desired. For example, in an experiment with wave energy foundations on the west coast of Sweden the potential for enhancing the abundance of associated fish and crustaceans through low-cost manipulations of the structural complexity of foundations was examined. Additional experiments will provide further guidance on the influence of different designs of foundations on commercially important fish and shellfish.
This presentation will focus on the potential influence of offshore wind and wave farms on fish and commercially important crustaceans. The uncertainties with regard to positive and negative effects of on benthic and pelagic assemblages and specific species will also be discussed. The presentation will draw on results from a number of field studies and experiments conducted in offshore wind and wave farms, as well as on secondary literature on the influence of differently designed artificial habitats on benthic fauna
Preface: the WinMon.BE 2013 conference: steps towards an efficient and effective offshore wind farm environmental impact assessment
Effects of offshore wind farms on marine wildlife
Marine management plans over the world express high expectations to the development of offshore wind energy. This would obviously contribute to renewable energy production, but potential conflicts with other usages of the marine landscape, as well as conservation interests, are evident. The present study synthesizes the current state of understanding on the effects of offshore wind farms on marine wildlife, in order to identify general versus local conclusions in published studies. The results were translated into a generalized impact assessment for coastal waters in Sweden, which covers a range of salinity conditions from marine to nearly fresh waters. Hence, the conclusions are potentially applicable to marine planning situations in various aquatic ecosystems. The assessment considered impact with respect to temporal and spatial extent of the pressure, effect within each ecosystem component, and level of certainty. Research on the environmental effects of offshore wind farms has gone through a rapid maturation and learning process, with the bulk of knowledge being developed within the past ten years. The studies showed a high level of consensus with respect to the construction phase, indicating that potential impacts on marine life should be carefully considered in marine spatial planning. Potential impacts during the operational phase were more locally variable, and could be either negative or positive depending on biological conditions as well as prevailing management goals. There was paucity in studies on cumulative impacts and long-term effects on the food web, as well as on combined effects with other human activities, such as the fisheries. These aspects remain key open issues for a sustainable marine spatial planning
Preface: the WinMon.BE 2013 conference: steps towards an efficient and effective offshore wind farm environmental impact assessment
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Offshore wind park monitoring programmes, lessons learned and recommendations for the future
Over a decade of monitoring offshore wind park environmental impact triggered a reflection on the overall objectives and how to best continue with the monitoring programmes. Essentially, basic monitoring has to be rationalised at the level of the likelihood of impact detection, the meaningfulness of impact size and representativeness of the findings. Targeted monitoring is crucial and should continue to be applied to disentangle processes behind observed impacts, for instance the overarching artificial reef effect caused by
wind parks. The major challenge, however, remains to achieve a reliable assessment of the cumulative impacts. A continuous international consultation and collaboration with marine scientists, managers, government officials and industry will be needed to ensure an optimisation of the future monitoring programmes
Modelling impacts of offshore wind farms on trophic web: the Courseulles-sur-Mer case study
International audienceThe French government is planning the construction of three offshore wind farms in Normandy. These offshorewind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbancessuch as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulativestressors on ecosystem functioning are still unknown, but they could impact their resilience, making themsusceptible to changes from one stable state to another.Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potentialstate changes, and to implement conservation actions in a sustainable manner. Currently, there are noglobal and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover,approaches are generally focused on the conservation of some species or groups of species. Here, we developa holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophicmodels describe the interaction between biological compartments at different trophic levels and are based on thequantification of flow of energy and matter in ecosystems. They allow the application of numerical methods forthe characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA).These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitiveto different impacts on marine ecosystems. We present here in detail the strategy for analysing the potentialenvironmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such asthe reef effect through the use of the Ecopath with Ecosim software. Similar Ecopath simulations will be made inthe future on the Le Tréport offshore wind farm site.Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems.They also allow to define recommendations for environmental managers and industry in terms of monitoring theeffects of Marine Renewable Energy, not only locally, but also on other sites, national and European levels. Finally,this approach could contribute to a better social acceptability of Marine Renewable Energy projects allowing aholistic vision of all pressures on ecosystem
Modelling impacts of offshore wind farms on trophic web: the Courseulles-sur-Mer case study
International audienceThe French government is planning the construction of three offshore wind farms in Normandy. These offshorewind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbancessuch as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulativestressors on ecosystem functioning are still unknown, but they could impact their resilience, making themsusceptible to changes from one stable state to another.Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potentialstate changes, and to implement conservation actions in a sustainable manner. Currently, there are noglobal and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover,approaches are generally focused on the conservation of some species or groups of species. Here, we developa holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophicmodels describe the interaction between biological compartments at different trophic levels and are based on thequantification of flow of energy and matter in ecosystems. They allow the application of numerical methods forthe characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA).These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitiveto different impacts on marine ecosystems. We present here in detail the strategy for analysing the potentialenvironmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such asthe reef effect through the use of the Ecopath with Ecosim software. Similar Ecopath simulations will be made inthe future on the Le Tréport offshore wind farm site.Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems.They also allow to define recommendations for environmental managers and industry in terms of monitoring theeffects of Marine Renewable Energy, not only locally, but also on other sites, national and European levels. Finally,this approach could contribute to a better social acceptability of Marine Renewable Energy projects allowing aholistic vision of all pressures on ecosystem
Benthic and fish aggregation inside an offshore wind farm: Which effects on the trophic web functioning?
International audienceThe French government is planning the construction of three offshore wind farms in Normandy. These offshore wind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbances such as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulative stressors on ecosystem functioning are still unknown, but they could impact their resilience, making them susceptible to changes from one stable state to another. Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potential state changes, and to implement conservation actions in a sustainable manner. Currently, there are no global and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover, approaches are generally focused on the conservation of some species or groups of species. Here, we develop a holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophic models describe the interaction between biological compartments at different trophic levels and are based on the quantification of flow of energy and matter in ecosystems. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. We present here in detail the strategy for analysing the potential environmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such as the reef effect through the use of the Ecopath with Ecosim software. Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems. They also allow to define recommendations for environmental managers and industry in terms of monitoring the effects of Marine Renewable Energy, not only locally, but also on other sites, national and European levels. Finally, this approach could contribute to a better social acceptability of Marine Renewable Energy projects allowing a holistic vision of all pressures on ecosystem
Benthic and fish aggregation inside an offshore wind farm: Which effects on the trophic web functioning?
International audienceThe French government is planning the construction of three offshore wind farms in Normandy. These offshore wind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbances such as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulative stressors on ecosystem functioning are still unknown, but they could impact their resilience, making them susceptible to changes from one stable state to another. Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potential state changes, and to implement conservation actions in a sustainable manner. Currently, there are no global and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover, approaches are generally focused on the conservation of some species or groups of species. Here, we develop a holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophic models describe the interaction between biological compartments at different trophic levels and are based on the quantification of flow of energy and matter in ecosystems. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. We present here in detail the strategy for analysing the potential environmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such as the reef effect through the use of the Ecopath with Ecosim software. Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems. They also allow to define recommendations for environmental managers and industry in terms of monitoring the effects of Marine Renewable Energy, not only locally, but also on other sites, national and European levels. Finally, this approach could contribute to a better social acceptability of Marine Renewable Energy projects allowing a holistic vision of all pressures on ecosystem