Changes to freshwater mussel assemblages after 25 years of impoundment and river habitat fragmentation

摘要: The Tennessee–Tombigbee Waterway is among the largest and most expensive environmental engineering projects of 20ᵗʰ century. waterway accommodates barge navigation between Tennessee River Drainage Mobile Basin through a series locks, dams, canals, dredged diverted streams. These structures have altered riverine habitat fragmented lotic habitats resulting in isolated freshwater mussel populations patches streams such as East Fork Tombigbee River, where 42 species were known historically. first post‐waterway surveys 1987 1988 reported 31 taxa. During 2010 2011 surveys, 70 sites sampled using both timed searches quadrats detected 29 extant species. Between 2010–2011 relative abundance nine taxa decreased, whereas 11 increased. three federally listed at levels below detection limits well non‐native unionids that appear to colonized via River. Although total richness relatively unchanged, assemblage composition shifted toward animals typical smaller rather than large rivers. This shift suggests present‐day favour smaller‐bodied, thinner shelled are laterally compressed lack shell sculpture. likely be better adapted hydrologically hydraulically variable thick‐shelled, bodied, sculptured mussels. results suggest assemblages dynamic may exhibit predictable responses changes hydrology, physical conditions, stream connectivity. However, examinations over broad (20+ yr) temporal scales needed observe these shifts. data demonstrate value regular monitoring diverse importance connectivity flow modifications this long‐lived group benthic invertebrates.