Habitat Use of Macrhybopsis Chubs and Population Structure of Shoal Chub in the Upper Mississippi River Basin

Human modifications to the river systems may have a significant impact on habit use and population structure of native fishes. We tested this hypothesis with Macrhybopsis chubs which are characteristic of large Great Plains Rivers and serve as important indicators for the health of ecosystems. Sampling was conducted from September 2013 through May 2015 from nine sites throughout the upper Mississippi River Basin. Diet analysis revealed all species of the genus are insectivore sight feeders whereas environmental analysis determined that shoal chubs preferred relatively shallow rivers with moderate currents and pebble substrate; unlike sicklefin and sturgeon chubs which preferred stronger currents and sand substrate and silver chubs which preferred deeper waters with stronger currents. Preliminary population genomic sequencing analysis revealed the genetic diversity of shoal chub is relatively poor (0.31-0.39). The results of this preliminary study suggest that the shoal chub may be particularly susceptible to anthropogenic disturbances due to low genetic diversity, and that the shoal chub may be an important indicator of environmental change.