Abstract
Although our understanding of the ecosystems of tropical rivers is limited compared to that of temperate rivers, the former having ecological and hydrological characteristics that are wide-ranging and often very different from those of the latter, Costa Rica stands out among tropical countries for the amount of information on rivers that is available. This chapter reviews the current state of our growing understanding of Costa Rican river ecosystems. First, the authors discuss riverine plants with a focus on algal periphyton and riverine animals including both vertebrates and invertebrates. The authors then describe species interactions in rivers ranging from mutualism, competition and predation to frugivory and seed dispersal by fishes and ecosystem functioning and dynamics on a broader level with an emphasis on biogeochemistry, nutrient cycling, primary productivity, and decomposition. Finally, the authors discuss human influences on the Costa Rican river system — focusing on the environmental effects of hydropower, land use changes, water withdrawals and invasive species — and stress the importance of maintaining the biointegrity of rivers for research needs and human survival as the rivers quickly change as a result of natural and anthropogenic influences.