The sustainability concept
The concept of sustainability gathers together the various elements contributing to a human life support system on Earth and follows the seminal approach established by the Brundtland report on sustainable development (WCED, 1987). Traditionally, sustainability is associated with criteria such as efficiency or equity from an economic viewpoint and deals with intragenerational and intergenerational issues. Nevertheless, this concept is difficult to seize and ambiguities arise. Sustainable development and therefore sustainability are linked not only by the three-way relationship between the environmental, economic, and social pillars but also by the institutional dimension of sustainable development. Prominent interactions exist respectively between the environmental and economic dimensions regarding viability and between the economic and social dimensions denoting equity. Furthermore, the distinction is conventionally made between weak sustainability as opposed to strong sustainability, allowing for a description of different types of capital and a total stock perspective. These types are natural capital, manufactured capital, human capital, social capital, and their substitutability determines the position held between weak sustainability and strong sustainability (e.g., the extent of replacement of degraded or destroyed natural capital by manufactured capital). The Brundtland report and Agenda 21 identify the need for sustainable development within the coastal zone. Gallagher et al. (2004) identify “key constructs” or “mobile concepts” of sustainability in a context of coastal management surrounded by professional coastal practitioners. In this analysis, sustainability becomes a guiding principle that may be viewed as a dominant paradigm, and may represent both the aim of coastal management plans and the means by which success is measured.
Sustainable development indicators
We must emphasise a shift in initiatives where indicators are constructed by pillars based on issues at stake. The European Union has thus recently drawn up guidelines and indicators concerning sustainable development whilst taking into account issues at stake (EUROSTAT, 2005). The aim is to integrate knowledge and create transversal bridges in order to link pillars and to encourage commitment of the people.