Deforestation is a phenomenon that affects the integrity of aquatic ecosystems. However, little is known about how this process affects trophic interactions of organisms, especially in the tropics. Food webs are considered as a tool for understanding the effect of disturbances on ecosystems. In the case of streams, they help to understand the dynamics between the riverine ecosystems and the terrestrial ecosystems in their basins, and to assess and propose mitigation and conservation strategies. This project seeks to characterize the food web of a stream located in the Serrania de La Lindosa in the dry and the wet season, inferring the role of allochthonous contributions of organic matter from the riparian forest on the trophic dynamics of streams ecosystems. The aim was to answer the question: Which could be the changes in trophic dynamics and then the changes in the availability of allochthonous resources? This was achieved through analyzing the stable isotopes signatures in the different compartments of the ecosystem and will be complemented by an analysis of gut contents in aquatic invertebrates, crustaceans, amphibians and fishes. Mathematical tools for the analysis of aquatic communities, as well as graphs and Bayesian models, elucidated the importance of autochthonous resources in the diet of consumers both in the dry season and in the wet season. However, it was recognized that through different mechanisms, allochthonous contributions are essential for the functioning of the ecosystems studied and could indirectly influence trophic dynamics. The answer to the research question, and the results of this thesis, allowed us to move forward to a better understanding and to anticipate the complex changes that are occurring due to the loss and degradation of the riparian forest of this region.