Factors affecting fish assemblage structure during seasonal stream drying

Abstract

Abstract – We evaluated fish assemblage structure during stream drying in north west Arkansas in 2002 and 2003. We sampled fish with a seine and backpack electrofisher and measured habitat variables along transects. Linear regression models were selected a priori and ranked according to Akaike's Information Criterion. In 2002, total fish density was negatively related to pool area and maximum depth, and positively related to canopy openness and substrate diversity. Similarly, central stoneroller (Campostoma anomalum, Rafinesque) and creek chub (Semotilus atromaculatus, Mitchill) densities were negatively related to maximum pool depth. In 2003, fish species richness was positively related to pool area whereas total fish, central stoneroller, and creek chub densities were negatively related to maximum pool depth. In addition, total fish density was negatively related to substrate diversity. Results indicated that physical factors are important predictors of fish assemblage structure during stream drying. However, differences among response variables between years indicated that the magnitude of stream drying might be critical in intermittent streams.