Relationships among geomorphology, habitat, and fishes in eastern Oklahoma streams: Implications for stream restoration

Scope and method of study. Stream restoration is a multidisciplinary practice aimed at reestablishing disturbed stream ecosystems. Fluvial geomorphology and landscape ecology have been individually incorporated into stream fish ecology. However, they have not been explicitly integrated into stream restoration practices. We used a stream survey to relate geomorphology and habitat to fish species composition and smallmouth bass Micropterus dolomieu abundance at several spatial scales in eastern Oklahoma streams. Spatial and temporal changes in stream habitat and population characteristics of smallmouth bass were determined for two eastern Oklahoma streams, and a landscape model was evaluated for smallmouth bass in Baron Fork Creek, Oklahoma.; Findings and conclusions. Stream survey results elucidated complex relationships between stream geomorphology and stream habitat, and fishes in eastern Oklahoma streams. Geomorphic variables representing stream size best explained variability in fish species composition in both northeastern and southeastern Oklahoma streams. Local channel morphology and substrate characteristics were secondarily important and mostly independent of stream size. Stream size and morphology explained variation in densities of all sizes of smallmouth bass, but channel unit habitat explained additional variation in densities of larger individuals. Stream habitat and smallmouth bass populations in Baron Fork Creek and Glover River were spatially and temporally dynamic. Water temperatures, streamflows, and instream habitat differed between streams and longitudinally within each stream. Abundance, recruitment, and survival of smallmouth bass populations differed between streams and seasons, and longitudinal patterns of these characteristics were unique in each stream. Smallmouth bass showed strong patterns of seasonal habitat complementation and supplementation: different habitats were used for spawning and summer growing periods versus those used for winter thermal refugia. Eastern Oklahoma streams are sensitive to disturbance but naturally resilient. Consideration of geomorphic relationships with fishes and ensuring that all habitats required by fishes are available will best facilitate responses from fish populations during the restoration of eastern Oklahoma streams.