This book addresses the question of the double exposure of marine ecosystems, i.e. to both global climate changes and economic globalization. This book contains a short, but self sufficient mathematical introduction, the formalization in the context of Network economics of global commodity chains, with both trophic and economic processes, and a series of cases studies, going from the re-addressing of fundamental ecological questions such as Gause's exclusion principles to practical studies such as the representation of the global supply chain for tuna.