Marine habitats off Shoreham, eastern English Channel : a geological perspective

The mapping of marine habitats will be an important requirement in the development of UK marine environmental policy. This will demand a systematic approach to the description and identification of ecosystems based on a number of characteristics including physical, chemical and biological attributes. Such an approach is being advanced with the development of marine habitat classifications and their implementation in mapping marine habitats in the coastal, shelf and ocean environment. A report recently completed by the British Geological Survey (James, 2002) identified and briefly described a number of marine habitat classification systems and examples of marine habitat mapping from the U.K. and overseas. The report also examined the use and application of geological data, maps and interpretation to the assessment and mapping of marine habitats. It was evident that geological and sediment data plays a very important role as a primary building block for habitat classification. One of the conclusions of the report was that geologists, biologists and ecologists in the U.K. should undertake co-operative research into the methodologies of surveying, sampling and interpreting marine habitats, and the value and use of geological data in the mapping of marine habitats in the U.K. This current report is a small step towards meeting these aims. CEFAS are currently completing a DEFRA funded project (AE0908) “Mapping of gravel biotopes and an examination of the factors controlling the distribution, type and diversity of their biological communities” (Brown and others, 2001). One of the objectives of the CEFAS research is to assess the utility of sea bed mapping techniques. Four areas have been surveyed between the Isle of Wight and Dungeness (Figure 1). The survey methods adopted include � Side scan � QTC-VIEW (Acoustic ground discrimination system) � Video � Grab and trawl sampling The British Geological Survey (BGS) have seismic reflection, side scan and sample data in this part of the English Channel and have produced geological maps at 1:250,000 scale covering the area. The availability of biological and geological data at a reasonable scale in this area was an opportunity to test the value and practicality of integrating geological and biological interpretations. Because of funding and time constraints only the main survey area of the CEFAS project has been studied for this report. The main survey area is a 28 km x 12 km box to the south of Shoreham, Sussex (Figure 1). The aims of this report are � Produce a sea bed facies map of the main survey area off Shoreham. � Describe the sea bed facies, bedforms and geology, and the utility of integrating biotope and geological interpretations. Also, if practicable, produce a combined biotope and sea bed facies map. � Assess if results from this project have any implications for habitat mapping methodologies which may be adopted elsewhere in the UK.