Poster Session 5, 3:15 PM - 4:00 PM: Campus Center Auditorium [A41]

Mussel Stranding in the Wheelwright Dam Impoundment

Presenter: Jacob Adam Sorensen

Faculty Sponsor: Allison Roy

School: UMass Amherst

Research Area: Environmental Science and Sustainability

ABSTRACT

Freshwater mussels (Unionidae) are an important group of freshwater organisms that face multiple threats and widespread decline. While dams fragment streams that mussels inhabit, their removal can negatively impact mussels and their habitat. Dam removal can cause rapid declines in water level in the dam’s impoundment (the area upstream of the dam with higher water level and lower flows than the free-flowing river), which can lead to widespread stranding events, whereby mussels are trapped in sediment as the water level declines. Spatial analysis of where stranding events occur within the impoundment during a dam removal could help to inform where mussels are most vulnerable to declining water levels. We surveyed stranded mussels at the Wheelwright Dam in Hardwick, Massachusetts during a multi-phase drawdown and dam removal. At 30 sites (15 locations with paired left and right bank sites) along a ~5 river km impoundment, we counted mussels and collected physical information (e.g., bed texture, bank slope, vegetation). Using this information, we modeled the relationship between mussel stranding and physical characteristics of the landscape to determine which factors put freshwater mussels most at risk during a dam removal. We also deployed trail cameras to monitor an additional three sites for signs of mussel predation. These findings could be beneficial for managers to focus conservation efforts such as mussel relocations in areas with the highest risk of stranding events.

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