Final answer:
Power and colleagues' study on Northern California river ecosystems supports the driver hypothesis, where non-native fish richness directly leads to native fish declines. Habitat alteration facilitates the invasion of non-native species.
Step-by-step explanation:
The question is about a study by Power and colleagues on Northern California river ecosystems. The study demonstrated that non-native fish richness in the rivers was a better predictor of native fish declines than measures of land use alteration or hydrologic modification. The study supports the driver hypothesis, where non-native fish richness directly leads to native fish declines, and habitat alteration facilitates the invasion of non-native species. This is seen in examples such as the introduction of largemouth bass leading to declines in native fish populations.