Climate change and multiple stressors in small tropical streams

Despite the importance of small tropical streams for maintaining freshwater biodiversity and providing essential ecosystem services to humans, relatively few studies have investigated multiple-stressor effects of climate and land-use change on these ecosystems, and how these effects may interact. To illustrate these knowledge gaps, we reviewed the current state of knowledge regarding the ecological impacts of climate change and catchment land use on small tropical streams. We consider the effects of predicted changes in streamflow dynamics and water temperatures on water chemistry, habitat structure, aquatic biota, and ecosystem processes. We highlight the pervasive individual effects of climate and land-use change on algal, macroinvertebrate, and fish communities, and in stream metabolism and decomposition processes. We also discuss potential responses of tropical streams in a multiple-stressor scenario, considering higher temperatures and shifts in hydrological dynamics. Finally, we identify six key knowledge gaps in the ecology of low-order tropical streams and indicate future research directions that may improve catchment management in the tropics to help alleviate climate-change impacts and biodiversity losses.