Biodiversity and bio-evaluation methods in transitional waters: a theoretical challenge

1 - This paper addresses the question of the weaknesses of the methodologies developed based on the analysis of the composition of benthic invertebrate communities in transitional waters.2 - Benthic communities are an important element of the bio-evaluation methodologies suggested for the Ecological Quality status of the European transitional and coastal waters in the context of the Water Framework Directive. It is argued that the assessment of Ecological Quality status requires both fundamental and applied science.3 - The lack of performance of many biotic indices under varying and highly fluctuating environmental conditions may well be related to weakness in theory supporting marine biodiversity.4 - We propose some possible approaches for future development in the field of biotic indices and marine biodiversity theory.