At a meeting on marine ecosystem modelling held in Barcelona in November 2010, a wide range of tools were introduced by their developers. An officer of the European Commission was invited to the meeting as a key client of these tools, and he severely criticized the tools presented as being useless. This criticism led to a strong reaction by the modellers and an interesting debate. In this paper we summarize part of this debate, focusing on one of the potential reasons why final users are not using these tools: the isomorphism between the ecosystem and its deterministic representation through mathematical equations is fragile and a new generation of maps is necessary to represent the intrinsic uncertainty of their dynamics through models