IMIS

The Benthic Quality Index has been recently developed in view of the implementation of the WFD (Rosenberg et al. 2004). It is based on the fact that sensitive species tend to become dominant relative to tolerant species during secondary succession. Sensitive species thus tend to be dominant in undisturbed environments, whereas tolerant species dominate in disturbed areas. According to Rosenberg et al. (2004), the level of sensitivity/tolerance of a given species can differ between geographical areas. In BQI, the level of sensitivity/tolerance is based on the analysis of each studied data set through the concept of ES500.05 (Rosenberg, 2004). Analyzed data sets must thus be large enough to allow for the assessment of ES500.05 (Rosenberg et al. 2005, Labrune et al. 2006, Zettler et al. 2006). This constitutes a severe limitation to the spread of the use of BQI, which is thus currently restricted to large data sets (Labrune et al., 2006). This difficulty could be overcome by computing ES500.05 for large sub areas (i.e. Arctic, Atlantic, North Sea and Mediterranean Sea). This was achieved by using the Macroben database of European soft-bottom macrofauna, built up by the MarBEF NoE. This resulted in the computation of ES500.05 of 767 species (corresponding 98.6% of total abundance) in the whole data base. Corresponding number of species and % of abundance were 171 (70.1%), 465 (99.9 %), 78 (45.3%) and 278 (72.9%) in the Arctic, North Sea, Atlantic and Mediterranean Sea, respectively. These lists are available to compute BQI values in small datasets.