Marine biodiversity is threatened by human impact. Though few marine species are regarded as being extinct due to Man, many species are critically endangered (e.g.the mon seal Monachus monachus), endangered (e.g. the mediterranean giant limpet Patella ferruginea) or vulnerable, i.e. dwindlongrapidly, although not threatened with extinction in the immediaite future (e.g. the marge mollusk pinna nobilis). There are also threats to ecosystems (ecodiversity), such as, in the Mediterranean, the Lythophyllum byssoides rim and the seagrass Posidonia oceanica meadow, Marine Protected Areas (MPA) were initially established to protect biodiversity via the removal of human exploitation and occupation. However, since the 1970, the notion of MPA has moved on to a more general concept of nature conservation, thne to amore dynamic one of nature management, within the framework of sustainable development. Today, the aims of MPAs are therefore six fold : nature conservation, public education, reference areas fo scintifis research, tourism, export of fish eggs, larvae and adults to adjacent areas and finally management of the various uses of the sea (e.g. commercial fishing, recreationnal fishing, pleasure boating and tourism) in such a way that they do not conflict with each other or with conservation aims. Mediterranean MPAs, especially the Port Cros National Park, illustrate the fact that they are rather characterized by the management of human activities than by a set of prohibitions and that there is no negative interaction between bioduversity conservation and artisanal fishing (i.e. small-scale commercial fishing), at least in the way it is done (i.e. with additional lining, etc.). Consequently, MPAs are generally of benefit to the economy (e.g. commercial fishing and tourism industry), not only wothin MPAs but also ion adjacent areas. They theredore constitute a powerful tool for integrated coastal management.