The role of salinity in structuring fish assemblages in a prairie stream system

We used fishery surveys from 1954 to 1957 to determine the relationship between salinity and prairie stream-fish assemblage composition prior to the major drought of the 1950s and subsequent anthropogenic modifications. A total of 78,93 1 fishes were captured, representing 13 families and 44 species. Species were classified as having low, moderate, or high salinity tolerances based on k-means Clustering of detrended correspondence scores. The proportion of species with high salinity tolerances was correlated positively (r = 0.74) with salinity, whereas the proportion of species with low (r = -0.69) or moderate (r = -0.36) tolerances was correlated strongly and negatively with salinity. Many of the low or moderate salinity tolerant species found in the 1950s were not collected in studies conducted 15 and 35 years later. Examination of these studies provides compelling evidence that salinity has been a dominant and persistent factor in affecting the structure of stream-fish assemblages for the past 50 years.