Response of river metabolism to restoration of flow in the Kissimmee River, Florida, U.S.A.

1. The single station diel oxygen curve method was used to determine the response of system metabolism to backfilling of a flood control canal and restoration of flow through the historic river channel of the Kissimmee River, a sub‐tropical, low gradient, blackwater river in central Florida, U.S.A. Gross primary productivity (GPP), community respiration (CR), the ratio of GPP/CR (P/R) and net daily metabolism (NDM) were estimated before and after canal backfilling and restoration of continuous flow through the river channel. 2. Restoration of flow through the river channel significantly increased reaeration rates and mean dissolved oxygen (DO) concentrations from <2 mg L^?1 before restoration of flow to 4.70 mg L^?1 after flow was restored. 3. Annual GPP and CR rates were 0.43 g O₂ m^?2 day^?1 and 1.61 g O₂ m^?2 day^?1 respectively, before restoration of flow. After restoration of flow, annual GPP and CR rates increased to 3.95 O₂ m^?2 day^?1 and 9.44 g O₂ m^?2 day^?1 respectively. 4. The ratio of P/R (mean of monthly values) increased from 0.29 during the prerestoration period to 0.51 after flow was restored, indicating an increase in autotrophic processes in the restored river channel. NDM values became more negative after flow was restored. 5. After flow was restored, metabolism parameters were generally similar to those reported for other blackwater river systems in the southeast U.S.A. Postrestoration DO concentrations met target values derived from free flowing, minimally impacted reference streams.