Why new methodological tools have been developed?

• Marine ecosystems are impacted by a diversified number of anthropogenic stressors including fishing, aquaculture, marine littering, chemical pollution and eutrophication, which act simultaneously and sometimes synergistically (e.g. Jackson et al. 2001; Pandolfi et al. 2003; Lotze et al. 2006).
• As target and non-target species of above stressors interact by establishing complex relationships (e.g. Jennings and Kaiser 1998; Jackson et al. 2001), human activities have direct and indirect impacts whose analysis is notably challenging. Marine ecosystems are also influenced by environmental natural fluctuations and variability (Cury et al. 2008; Link et al. 2010).
• Thus, the ability to understand how these human activities, environmental factors and ecological components interact and influence each other, and eventually how the services and products provided to humans are affected, is a key issue that is of growing importance. Understanding these interactions and influences requires adoption of an ecosystem approach to the management of marine resources.
• For the ecosystem-based approach to marine resources management, adaptations to the scientific method are required, in parallel with changes in the way ecological, social and economic issues are integrated to manage marine resources (Browman et al. 2005). New methodological tools have been developed that contribute to this purpose, such as a selection of ecosystem indicators (e.g. Jennings 2005; Shin and Shannon 2010) and ecological models (e.g. Shin et al. 2004; Plaganyi 2007; Fulton 2010).