Physical characterization of freshwater mussel habitats in Upper Mississippi River Pool 16

Human activities in the Upper Mississippi River (UMR) Basin over the last century have caused a significant decline in freshwater mussel populations. One major contributing factor is the construction of navigation dams and river training structures on the main stem of the UMR. These structures have resulted in the slowing and redirection of flow through the braided channel system, severely impacting mussel habitats. The present research is intended to develop a more complete understanding of the physical characteristics of persistent mussel habitats to provide information useful in the preservation and restoration of imperiled UMR mussel populations. The study examines the hypothesis that heterogeneity of physical parameters is related to habitat quality, and can therefore be used to make predictions about the spatial distribution of freshwater mussels in the UMR.; In 2002, IIHR - Hydroscience & Engineering established the Lucile A. Carver Mississippi Riverside Environmental Research Station (LACMRERS), interdisciplinary center for large rivers research. The present research was initiated to create a bathymetric and hydrodynamic baseline data set in UMR navigation Pool 16 (Pool 16), a 41-km reach adjacent to LACMRERS, and to apply these data to the investigation of the physical habitat characteristics of freshwater mussels.; The project uses field sampling and numerical simulation to quantify hydrodynamic and substrate characteristics within UMR freshwater mussel habitats. Published data describing mussel dispersal, field data describing physical parameters, and computational fluid dynamics (CFD) simulations of flows within Pool 16 are combined in a geospatial database and analyzed using multivariate statistical methods to evaluate relationships between mussel assemblages and their physical habitat. Analyses examine influences of individual parameters on habitat quality and develop simple, statistically based predictive models. Results identify trends in habitat preference and the relative influence of physical parameters, demonstrate the value of binary logistic regression as a predictive tool, and suggest geometric features associated with tributary streams may be related to habitat quality.