Global-scale coordinated networks as a tool for exploring the functioning of stream ecosystems

Individual ecological studies, although suitable for testing hypotheses and developing theory, provide site-or region-specific information that is difficult to extrapolate to provide broad generalizations. Today, emerging globally relevant questions (e.g., climate change, biodiversity loss, invasive species or habitat degradation) require a reconsideration of what approaches would be best for understanding large-scale ecological patterns and processes. A technique commonly used for this purpose is metaanalysis, a quantitative approach to reviewing, integrating, and summarizing large numbers of independent studies. However, the robustness of a meta-Analysis relies on the individual studies selected for inclusion, and issues of scale and methodology cannot be controlled retrospectively. An emerging, alternative approach is global-scale coordinated experiments, run in parallel by several research groups in multiple locations around the globe. These experiments have the advantage of addressing global problems and exploring general ecological theory, while offering the precision of controlled experiments. Here we review the existing global-scale experiments conducted by stream ecologists and discuss the potential of this type of study for developing ecological theory and advancing our understanding of stream ecosystem functioning.