Evaluation of the influence of thermal and hydrologic regime on native fish communities in the upper Chattahoochee River

Modifications to the hydrologic and thermal (hydrothermal) regimes in regulated rivers can negatively affect native streamfish reproduction and persistence. Using hierarchical linear modeling, I evaluated the relative support for models representing hypothesized influences of streamflow and fish life history characteristics on recruitment of young-of-year fishes using existing datasets from three warmwater rivers. Using these results, I constructed decision models that predicted how native fishes are affected by flow regulation in the upper Chattahoochee River, GA according to species-specific life-history traits. I found that short-term maximum discharge during spawning periods and short-term variation in discharge during rearing periods had an influence on young-of-year recruitment. I also found that life history characteristics affected recruitment success and modified the influence of discharge characteristics. These findings suggest that that environmental variability can have a substantial effect on the success on native fishes.