Simulating the effect of invasive species on native freshwater mussel communities

Abstract

The dispersion of invasive species is a serious problem worldwide. In North America in particular, the introduction of the zebra mussel (Dreissena polymorpha) has caused millions of dollars in economic losses and environmental damage. This paper uses ecohydraulics modeling to analyze the effects of zebra mussels on native freshwater mussel communities (unionids) in the Upper Mississippi River (UMR), USA. The model takes into account environmental forcing functions and individual mussel interactions in the form of food competition. First, hydrodynamic transport of incoming zebra mussel larvae was simulated to assess their colonization patterns on unionids. Next, population growth at various food availabilities was computed. Simulated zebra mussel densities were within the range observed in published studies and survival rates of unionids coincided with reported values for an upstream reach of the UMR. These results suggest that these two families of species may coexiste in the UMR, although the sharp decline in the unionid populations may eventually result in extirpation due to unsuccessful egg fertilization. This model provides the means for better understanding the interaction between native and invasive freshwater mussel species and it may be a valuable tool supporting the development of appropriate conservation strategies for unionids.