Comparison of Fish Communities of the Lower Missouri (rm 0 – 545) and Unimpounded Upper Mississippi Rivers (rm 0 – 194)
James E. Wallace and Valerie A. Barko
Missouri Department of Conservation, Open Rivers and Wetlands Field Station, Cape Girardeau, Missouri
We collected fish data from the unimpounded Upper Mississippi and Lower Missouri Rivers from 2004-2006 using EMAP-GRE electrofishing protocol. This method was used to collect fishes in nearshore littoral habitats at each site. We collected 55 species representing 17 families in the Mississippi River and 69 species representing 13 families in the Missouri River during the three years of sampling. Overall, there were 29 samples collected from the Mississippi River and 86 samples collected from the Missouri River. Data were analyzed using univariate statistics, ecological metrics, and multivariate methods to describe, compare, and contrast Missouri and Mississippi fish assemblage structure. We found that species richness, number of individuals captured per sample, and Shannon’s Diversity Index were all lower in the Mississippi River when compared to the Missouri River. Fish assemblage structure was significantly different among the two rivers (R = 0.466, P < .001) and among the years (R = 0.154, P < 0.001). Six species cumulatively explained approximately 50 % to the dissimilarity among these communities and included gizzard shad (Dorosoma cepedianum), emerald shiner (Notropis antherinoides), freshwater drum (Aplodinotus grunniens), red shiner (Cyprinella lutrensis), threadfin shad (D. petenense), and goldeye (Hiodon alosoides). The Missouri River fish community exhibited significant changes in assemblage structure in an upstream direction and clustered into seven distinct groups. Similar patterns were not observed in the Mississippi River fish assemblage as distance from the confluence increased and no significant clusters were evident.
Keywords: unimpounded, fishes, assemblage, large river, Missouri