Defining freshwater mussel mesohabitat associations in an alluvial, Coastal Plain river

Abstract

AbstractDefining freshwater mussel habitat in large, turbid rivers is challenging but essential to effective conservation. Hydraulic investigations have confirmed that mussels persist in discrete flow refugia, areas where riverbed sediment is stable during high-discharge events. However, approaches to identify these patches often involve detailed field measurements or mathematical models that may limit their applications across wide spatial extents. We used low-cost, sonar habitat mapping to delineate a mesohabitat classification scheme based primarily upon variations in substrate bedforms and position within the river channel. Bedforms in sand-bed rivers function as indicators of turbulent flow and hydraulic conditions at the sediment–water interface. We used the resulting map to conduct a stratified mussel survey to assess mussel–habitat associations at multiple scales. In addition, we assessed habitat persistence by remapping a portion of the study area following flood-level discharge events and conduc...