Ecological assessment of marine systems: How to conclude? Method and application to Western Mediterranean

The ecosystem approach is generally considered as the best way to manage human activities impacting the marine environment. Nevertheless, more than 20 years after the emergence of this new paradigm, whereas ecosystem-based management is theoretically implemented through an essentially systemic approach, in practice, it appears that the application of standards and criteria and the use of indicators lead to a predominance of analytical approaches and to reporting formats that are inappropriate for defining action programmes. This paper proposes a new methodological framework to produce, in a synthetic form, integrated ecosystem assessments that go beyond the juxtaposition of sectoral analyses. Its guiding principle is to use the general knowledge of the marine environment (understanding of system dynamics and interactions within the system through a systemic approach) to put into perspective the results obtained through criteria and methodological standards (understanding the state of ecological components and the pressures affecting them through analytical approaches). The new methodological framework includes the identification of appropriate typologies for activities and pressures, as well as for ecological components. An essential point is to group the ecological components within the following compartments: pelagic habitats and food webs; benthic habitats; areas at the land-sea interface; protected species; and commercial species. On each of these compartments, the application of a selection of descriptors is possible. The result is an optimization of analyses in comparison with the indiscriminate use of descriptors on each of the ecological components considered separately. A case study is presented on the French Western Mediterranean.