Fish biodiversity is important for many ecosystem services provided by freshwater systems.  Nevertheless, human development plans such as the construction of dams and setting pollution regulations typically ignore their impact on sustaining fish diversity. Furthermore, climate change has recently been identified as a potential driver of terrestrial and aquatic species extinction.

In this work we extend a previously published neutral meta-community model (Muneepeerakul et al. Nature 2008). Previous studies showed that the fish biodiversity indices in the Mississippi-Missouri river system (MMRS) are well described using this simple mathematical model, which considers only the network topology, runoff productions and neutral dynamics. Our preliminary work focused on the impact of damming on the biodiversity in the MMRS. We model the impact of dam construction by changing the dispersal kernel of fish, either limiting or preventing upstream/downstream dispersal.

Results/Conclusions

There are 30 large built on the Mississippi-Missouri. We find that dams reduce biodiversity locally, and to a lesser extent globally. Also, we observe a reduction in range and occupancy of common species, as well as reduced similarity between species compositions of different local communities. The impact of particular dams depends on the pre-existing local species richness, as well as the degree of network connectivity in the surrounding catchments. Our results shed light on the potential impact of flow modifications on migratory and non-migratory fish.