Fish faunal breaks and stream order in the eastern and central United States

The distribution of fishes within 23 streams in the eastern and central United States was analyzed for evidence of distinct longitudinal faunal "breaks", and to compare location of the breaks to stream order and longitudinal position of stations within watersheds. On the basis of presence-absence data for fish species, distinct faunal breaks were found in only 8 of the 23 streams. Qualitative faunal breaks were not significantly more common in any particular reach of stream, and the breaks did not correspond to changes in stream order. In 11 of 14 streams for which data on fish abundance were available, quantitative faunal breaks were found, but the locations of these breaks were unrelated to stream order or longitudinal position of stations in streams.