SEASONAL-VARIATION OF RIFFLE AND POOL FISH ASSEMBLAGES IN A SHORT MITIGATED STREAM REACH

We sampled a series of contiguous rimes and pools throughout one year to examine spatial and temporal variation in stream fish assemblages o n a short, mitigated reach of the Cottonwood River, Kansas. One of thr ee rimes sampled was an artificial rime constructed as habitat restora tion in an area previously dredged of gravel. Canonical correspondence analysis demonstrated differences between rime and pool fish assembla ges, and indicated seasonal assemblage variation with no influence imp arted by the artificial rime. Current speed, water depth, substrate ch aracter, total alkalinity, and season explained most assemblage variat ion. Fish assemblages were similar spatially, but, were seasonally var iable. Rime fish assemblages exhibited more seasonal variability than did those of pools; 59% of the total number of fishes captured in rime s were seasonally variable compared to 12% in pools. Patterns of varia bility in this mitigated stream reach were similar to those reported f or natural streams.