Many climate models predict warmer and drier conditions throughout the tropics, yet it is unclear how the changes will impact tropical streams. Using a naturally occurring rainfall gradient along the north Hilo coastline of Hawaii Island, Forest Service scientists monitored how stream flow and various ecological parameters from 12 streams responded to changes in rainfall. Stream flow, flow stability, and flashiness all decreased with decreasing rainfall, while flow variability increased. Reduced stream flow resulted in a shift in invertebrate production, decreased algal growth, food quantity but not quality, and decreased invertebrate fitness. Shrimp egg production decreased with decreasing stream flow as did the timing and frequency of shrimp larvae to the water column.