Enrichment of the soft sediment macrobenthos around a gravity based foundation on the Thorntonbank
Coates, D.; Vanaverbeke, J.; Vincx, M. (2012). Enrichment of the soft sediment macrobenthos around a gravity based foundation on the Thorntonbank, in: Degraer, S. et al. (Ed.) Offshore wind farms in the Belgian part of the North Sea: Heading for an understanding of environmental impacts. pp. 41-54 In: Degraer, S.; Brabant, R.; Rumes, B. (Ed.) (2012). Offshore wind farms in the Belgian part of the North Sea: Heading for an understanding of environmental impacts. Royal Belgian Institute of Natural Sciences, Management Unit of the North Sea Mathematical Models, Marine Ecosystem Management Unit: Brussel. 155 + annexes pp., more |
| Abstract | Belgium initiated a large scale monitoring programme in 2005 to determine the effects of offshore wind farms on the soft sediment macrobenthos. Up till now, the natural, temporal variability of the macrobenthos was detected without any apparent effects from the foundations (Coates & Vincx, 2010; Reubens et al., 2009). In 2011, the soft-sediment macrobenthos in close vicinity to one gravity based foundation on the Thorntonbank was analysed. Bottom samples taken at 15, 25, 50, 100 and 200 meters from the scour protection system of the foundation and in four gradients around the turbine (Southwest, Southeast, Northwest and Northeast), showed a clear distinction in densities. The median grain size showed a declining trend at stations closer to the turbine. An accumulation of juvenile starfish (Asteriidae juv.) together with the polychaetes Spio sp. and Spiophanes bombyx was obvious at stations <50 meters and mostly on the Southwest gradient. Lower current speeds and changing granulometric characteristics appear to be creating a substantial change in the macrobenthic community on the Southwest gradient. The soft sediment macrobenthic community around the foundation is highly dynamic and far from reaching an equilibrium. |
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