Larval Fish Ecology in Restored Habitats in the Lower Missouri River

Abstract

Anthropogenic alterations to aquatic ecosystems have greatly reduced and homogenized riverine habitat, especially those used by larval and juvenile fishes. Creation of shallow-water habitats is used as a restoration technique in response to altered conditions in several studies globally, but only recently on large rivers in the United States. In the summer of 2012, the U.S. Army Corps of Engineers sampled larval and juvenile fishes at six paired sites (mainstem and constructed chute shallow-water habitats) along a section of the Missouri River between Rulo, NE and St Louis, MO. From those samples, we enumerated and identified a total of 7,622 fishes representing 12 families. Community responses of fishes to created shallow-water habitats were assessed by comparisons of species richness and diversity measures between paired sites and among sampling events. Shannon entropy measures were transformed and γ diversity (total diversity) was partitioned into two components, α (within community) and β (between community) diversity using a multiplicative decomposition method. Mantel test results suggest site location, time of sampling event, and habitat type were drivers of larval and juvenile community structure. Paired t-test results indicated little to no differences between in beta diversity between habitat types, however, chute habitats had significantly higher alpha and gamma as well as increased numbers of Asian Carp larvae when compared to mainstem shallow-water habitat. Feeding patterns of Freshwater Drum indicate a greater number of chironomid larvae were consumed in mainstem reaches when compared to chutes. Chute habitats also had significantly greater numbers of individuals with empty stomachs.