Abstract : Biological diversity allows to see unity laws related to nature, at different levels : genes, species and ecosystems. Through this prism, biological diversity laws deal with environmental protection, appropriation of biological diversity elements and related knowledge. It includes all juridical links between human and nature. This characteristics reveals particularly when concerning seas and oceans because of its juridical particularities about appropriation. Biological diversity puts together while putting in order, the ecosystem approach being a way to manage nature with coherence. This approach implies a process based upon integration, cooperation, considering time with precaution principle and adaptivity. It allows a holistic decision-making process based upon a unity that is scientifically and socially coherent, and implies a common responsibility for acting. It makes the citizen at he centre of the decision-making.