COS 41-3 - Not Set in Stone: Morphometric changes in native fishes in response to invasive carp density in the Kansas River

Abstract: Invasive carp species were introduced to the United States in the 1970s, quickly thereafter becoming an established and invasive population with drastic effects on native aquatic systems. Invasive carp are larger bodied fish primarily feeding on zooplankton suspended in the water column (planktivore). In fish, things such as feeding mode and diet may have environmental factors causing change in body shape, gill raker morphology, and pharyngeal jaw morphology. The objectives of this study were to gain a deeper understanding of the phenotypic plasticity and genetic response of native planktivores at varying densities of invasive carp in the Kansas River. Our approach to addressing our objectives was a series of sampling at three different sites located on the Kansas River which presents the ideal natural experimental design, with a series of manmade barriers preventing invasive carp from traveling freely upstream. Eight species of native fishes were collected from 3 stretches in the Kansas River with no, medium, and high densities of carp. We looked at whether feeding morphology, body shape and gill raker morphology, in native species shifted due to competition with invasive carp. Here we show there are specific shifts in morphology of native species dependent on size class and density of carp. We see shifts in body condition and can use body condition of native species to predict impacts of invasive carp on native communities. In conclusion, this study provides a greater understanding of the impacts of invasive carp invasions on native ecosystems. The results of this study can be used for predicting future river invasions and tracking invasive pressure on native species.