Mangroves are part of rich ecosystems providing a variety of environmental goods and services. Underestimation of their value and of the impacts of human activities is a major factor contributing to the widespread loss and degradation of ecosystems. Economists frequently receive the blame for such environmental ills, but it can also be argued that ecologists communicate inadequately their knowledge to decision makers and therefore have limited influence. This article links information supplied by ecologists to the information required for effective and efficient mangrove management. A key problem which ecologists face is the high degree of interconnectedness within and between ecosystems. This makes it difficult to predict what is going to happen, let alone understand what is going on. The concept of 'environmental function' is used in combination with system diagrams to address this problem. System diagrams are used to identify and assess goods and services produced by the system under different management regimes. These goods and services are then valued to enable assessment of the economic efficiency of the management regimes.