original_query: What did the study conducted in central California demonstrate about gravel augmentation and its impact on Chinook salmon spawning habitat?
query: What did the study conducted in central California demonstrate about gravel augmentation and its impact on Chinook salmon spawning habitat?
answer: A study in California's Merced River showed that gravel augmentation enhanced Chinook salmon spawning habitat, but also created abnormally mobile streambeds which damaged salmon eggs, reduced food, and altered the feeding, survival, and growth of native fish.