High-elevation streams have heterogeneous water sources that influence biodiversity patterns. The tropical high Andes of South America have two major stream types: glacier-fed and groundwater-fed. Glacier-fed streams have much more dynamic flow and temperature patterns than groundwater-fed streams. We collected macroinvertebrates from both stream types on two glaciated volcanoes in Ecuador (Cotopaxi and Chimborazo) to evaluate if macroinvertebrate community structure varied consistently between the two stream types and/or between the two mountains. We addressed these questions in five paired glacier-fed /groundwater-fed streams, each sampled at ~4000 meters asl. Each pair shared a common watershed and converged downstream of our sample locations, with three pairs on Cotopaxi and two on Chimborazo. We quantitatively sampled benthic macroinvertebrates from each of the ten streams on nine evenly distributed dates from September 2014 through August 2015. We then calculated abundance, taxa richness, and temporal stability of community structure through the year-long study period. We’re also assessing overall patterns of community structure between stream types and between the two mountains using nonmetric multidimensional scaling. Sample processing is ongoing, but preliminary results suggest differences in community structure between stream types but not between the two mountains. Results from Cotopaxi are complete and indicate that groundwater-fed streams have higher abundance and taxa richness than glacier-fed streams, but communities in the two stream types have similar temporal stability. The unexpected community stability in physically dynamic glacier-fed streams could be due to adaptations conferring resistance or resilience to harsh physical conditions. Climate change is progressing rapidly in these and other high-elevation regions, and studies like this are crucial for understanding the ecology of these systems as the cryosphere continues to shrink.