TY - RPRT
TI - Gwynt y Môr Offshore Wind Farm Pre-construction Baseline Benthic Grab Survey
AU - Centre for Marine and Coastal Studies Ltd (CMACS)
AB - This report presents the findings of the Gwynt y Môr Offshore Wind Farm (GYM) pre-construction (baseline) benthic ecology survey undertaken in September/October 2010. The survey is part of a programme to monitor the status of benthic organisms and seabed sediments to allow the identification of any significant adverse effects resulting from the construction and operation of GYM OWF. The monitoring is a condition of Licence No: 10/59/F issued to Gwynt y Môr Offshore Wind Farm Ltd under the Food and Environment Protection Act (FEPA); the survey methodologies and programme have been reviewed and approved by the Licence Authority (Welsh Assembly Government)Offshore construction works are scheduled to commence in November 2011 and the baseline benthic ecology survey was therefore undertaken a little over 12 months in advance of this date. The main objective of the pre-construction survey is to establish a baseline description of benthic invertebrate communities and sediment conditions. The monitoring is also intended to test conclusions made in the EIA that there would be no significant adverse impacts on benthic ecological communities as a result of construction and operation of the wind farm.The benthic ecology monitoring programme was informed by characterisation surveys undertaken at the GYM OWF site for the Environmental Impact Assessment (EIA) in 2005. Survey methods comprised grab and beam trawl sampling, as used in 2005, with the addition of drop-down camera deployment for areas where there had previously been difficulty obtaining samples due to hard substratum.The draft Monitoring Method Statement was submitted to the Licensing Authority and their technical advisors for consultation. The sample site selection process incorporated information such as planned turbine placements and cable alignments and sample sites were distributed to provide good coverage of the wind farm development area itself (turbine array and electricity export cable corridor), together with near-field and reference areas.The grab and underwater camera surveys were completed using the survey vessel ‘Aquadynamic’ operating from Conwy Marina between 21st September-3rd October, 2010. The beam trawl survey was completed using the survey vessel ‘Halcyon Days’ between 27th September-3rd October, 2010 from the Port of Liverpool.Sediment samples from grabs were analysed for Total Organic Carbon and Particle Size. Benthic infauna from grabs and epifauna from trawls were identified to species level wherever possible and enumerated. Images from the camera survey were reviewed and all visible organisms identified and enumerated.Across the survey area, the sediments are described as coarse sands and gravel.Flatfish such as plaice, dab and solenette dominated the trawl survey samples while very low numbers of elasmobranch species (sharks and rays) were recorded. Epifaunal invertebrate communities were dominated by common starfish, Asterias rubens and colonial organisms such as cnidarians and bryozoans. No rare or unusual species were recorded in the trawl surveys.Overall, the infaunal community of the area is described as being relatively rich with a total of 408 taxa recorded from the grab samples. The number of taxa in grabs was greatest in the northern part of the survey area including sites within the GYM OWF and specifically at sites in the north eastern part of the wind farm area. The numerically dominant fauna were annelid worms. No protected benthic species were recorded but the rare thumbnail crab, Thia scutellata was present.Results from the camera survey showed the presence of three distinct habitat types: sand; sand with shell fragments; and pebbles and cobbles with pebbles. Low numbers of epifauna were recorded from the camera survey.Community descriptions against the JNCC’s biotope classifications were made using the BioScribe v1.2 tool and through statistical analysis of the grab data. Consideration was also given to the epifaunal data from the trawl and camera surveys. Four main biotopes were described:1. SS.SCS.ICS.MoeVen (Moerella spp. with venerid bivalves in infralittoral gravelly sand biotope);2. SS.SSA.CfiSa (Circalittoral fine sand biotope complex);3. SS.SSA.IfiSa.NcirBat (Nepthtys cirrosa and Bathyporeia spp. in infralittoral sand)4. SS.SSA.IMuSa.FfabMag (Fabulina fabula and Magelona mirabilis with venerid bivalves).The first two biotopes were extensive throughout the survey area. The third dominated the inshore reference sites but was also present at some locations within the GYM OWF array site itself. The fourth was present at the inshore reference sites and cable route locations. These biotope classifications and their distributions are consistent with the biotopes described during the GYM OWF EIA.The data collected provides a baseline against which future data sets can be compared to investigate whether construction and operation of the wind farm has had a significant impact on benthic invertebrate communities and sediments.
DA - 2010/11//
PY - 2010
SP - 239
PB - Centre for Marine and Coastal Studies Ltd (CMACS)
UR - https://www.marinedataexchange.co.uk/details/TCE-577/2010-2011-centre-for-marine-and-coastal-studies-ltd-cmacs-gwynt-y-mor-offshore-wind-farm-pre-construction-baseline-benthic-grab-survey/packages/2448?type=Report&directory=%2F
LA - English
KW - Wind Energy
KW - Fixed Offshore Wind
KW - Physical Environment
ER -