Phytoplankton Survival in Hindgut of Invasive Silver Carp (Hypophthalmichthys molitrix)

Abstract. The ability of organisms to survive ingestion and digestion by their predators, or endozoochory, is a fascinating ecological phenomenon that can facilitate predator-mediated dispersal of prey and alter interaction strengths within ecological networks. However, the role of endozoochory in the context of invasive species is considered less often. Throughout the United States, Silver Carp (Hypophthalmichthys molitrix) are prolific invaders that often alter food web structure of recipient ecosystems through the consumption of basal resources. Despite the biogeochemical and food web effects of Silver Carp, there is limited understanding of plankton prey survival after Silver Carp consumption and digestion, and even less known about the ecological effects of selective diets and potential survival. In this study, we quantify hindgut contents of Silver Carp collected from Kentucky Lake, Kentucky, Tennessee River Valley, United States. We found the majority (83%) of phytoplankters within hindguts of Silver Carp showed little digestion prior to egestion. Our study suggests digestion limitations of Silver Carp may have important ecological implications for invaded environments. These results may be applicable in understanding how this rapidly spreading invasive fish can influence food web dynamics and biogeochemical cycles pertinent to toxic algal blooms within recently invaded ecosystems, and forecasting invasion in the near future.