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FEATURES - Sub-tidal Sandbanks at Outer Thames Estuary Broadscale study on the sub-tidal sandbanks 2005
In 2005, Emu Limited was commissioned by English Nature to conduct a broadscale study on the sub-tidal sandbanks at the approaches to the Outer Thames Estuary. The purpose of the study was to record and characterise the sub-tidal sandbank habitat and map the macrofaunal biotopes with the intention of submitting this area as candidate for Special Area of Conservation (SAC) status as described in the European Habitats Directive Annex I and the UK Biodiversity Action Plan and the EC Habitats Directive, Annex I under the heading ‘Sandbanks which are slightly covered by sea water all the time’.
The survey was designed to characterise the physical extent of the sandbank and surrounding habitats up to 12 nautical miles from the coast using side scan sonar, single beam echo sounder and AGDS systems. A characterisation of the richness and diversity of biotopes and species supported by the sandbank features and the surrounding habitats was made using Day and Mini–Hamon Grabs and a 2 Metre Beam Trawl to sample the fauna and ground truth the surface sediment composition. Over 150 samples were investigated for faunal composition, sediment particle size and organic matter content.
Around 250 macrofaunal species were recorded in the survey area overall. Univariate and multivariate statistics using the PRIMER were applied to the sediment and faunal datasets to describe the richness and diversity of the biological communities and the community structure and variability in relation to the physical environment.
The biotopes described by Emu Ltd appear to fulfil the criteria for the SAC designation for subtidal sandbanks. The report will be used by the English Nature to assist with decisions on the future management, conservation and possible protection of this large sandbank system.
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