Wetlands are among the most productive environments in the world. Around 6% of the Earth's land surface is covered by wetlands, which are key to preserving biodiversity. Wetlands provide multiple services like a source for water supply and a shelter for numerous species of fauna and flora. Wetlands are therefore of immense socio-economic as well as ecological importance. In this research the focus was on the Abras de Mantequilla (AdM) wetland, a tropical wetland system that belongs to the most important coastal river basin of Ecuador. It was declared a Ramsar site in 2000 and was the South American case of the EU-FP7 WETwin project, which provided the starting point of this thesis. A range of tools and approaches was used to develop a knowledge base for the AdM wetland. The research involved a combination of primary data collection (two fieldwork campaigns), secondary data acquisition (from literature), multivariate analyses, and numerical modelling approaches to explore the characteristics of the wetland system in terms of hydrological conditions, hydrodynamic patterns, biotic communities, chemical and ecological processes and fish-habitat suitability.