Water-electricity Nexus: Assessing Impacts of Habitat Loss on Freshwater Mussel Assemblages in the Savannah Basin, South Carolina

摘要

The environmental effects of energy production are well known, yet its exact impacts on freshwater resources are often difficult to recognize and measure. Freshwater mussels are extremely imperiled organisms which act as sentinels of freshwater streams and are greatly understudied in context of their drastic decline caused in part due to large water demands by the energy sector. I sought to estimate historic, current and forecasted water use by electricity generation at national, regional and local scale. To relate the impacts of water-use by electricity generation on freshwater mussels, I conducted occupancy surveys for eight freshwater mussel species in Savannah River Basin, South Carolina. I modeled landscape and local factors potentially influencing occupancy and assessed whether the occupancy of species indicated vulnerability to the presence of impoundments. I also modeled the viability of the endangered Carolina heelsplitter (Lasmigona decorata) metapopulation in response to habitat loss caused by water appropriation associated with the energy sector. The results suggest that water-use is projected to increase in the future irrespective of clean energy policies and variety of energy mix. The water consumption is predicted to increase at a local scale and the water withdrawals will vary spatially and temporally. The site occupancy varied with species and was significantly correlated with local habitat factors such as stream width and substrate heterogeneity and landscape driven factors such as % forest and presence of impoundment. The Carolina heelsplitter metapopulation exhibited a gradual decline in response to both habitat degradation and fragmentation for both effective population sizes, but the effect was more significant at lower population sizes. The findings of this dissertation suggest that mussel assemblages in the Savannah river basin are more likely to benefit from habitat restoration than the removal of dispersal barriers and management efforts for threatened mussel species should prioritize habitat protection and restoration.