Marine habitat classification: a pluridisciplinary approach in a high macrotidal environment - The case of the English median Channel
Résumé
In megatidal sea, benthic marine communities are strongly dependent on the substrate, which is fashioned by hydrodynamism. This interdependence between substrate and benthic communities has enabled the establishment of marine benthic habitats classifications. Such classification allows depicting at the same time the general habitats diversity at the scale of a given shelf, and the local variations at the scale of a smaller area. Indeed, it meets diverse needs for ecological description of the marine environment such as general habitat knowledge or environmental impact assessment. The EUNIS classification is available to describe the main habitats of the European marine seabeds (Davies et al., 2004). Based on available data at the time of its delivery, it is well adapted to describe shallow bays and estuarine environments, mostly characterised by mobile muddy fine sediments. On the contrary it fails in describing correctly clean coarser sediments habitats in more deep areas such as those found in the central part of English Channel (La Manche) (Connor, 2005; James et al., 2007). This continental shelf sea connects with the Atlantic Ocean in its western part and to the Southern North Sea in its eastern part. It is characterised by a series of strong offshore-inshore and capes/bays gradients characterised by progressive changes in temperature, bathymetry, shear stress that are registered in the sediment, but also in the benthic communities.