Alayna C. Dorobek's Graduate Defense Seminar
Alayna C. Dorobek, MS candidate in Fisheries and Wildlife Science, will present her Graduate Defense Seminar on Short-term Consequences of Lowhead Dam Removal for Fish Community Dynamics in an Urban River System. This seminar will be held at the Schiemeier Olentangy River Wetland Research Park.
Dam removal has become an increasingly popular stream and river restoration technique. However, understanding the ecological consequences of the removal of lowhead dams (< 7.5 m in height, run-of-river structures) remains in the early stages, and many of the results related to fish assemblages are highly variable. Furthermore, the mechanisms driving shifts in fish assemblages as a consequence of dam removal remain unresolved. Here, I considered theoretical and applied implications of dam removal for fish community dynamics. Based on a 3-year field study on the Olentangy and Scioto Rivers (Columbus, Ohio), I found that lowhead dam removal acted as an ecological disturbance, leading to shifts in fish assemblage diversity and food-web structure in the short term (≤ 3 years). For example, I observed significant declines in species richness and food-web properties such as food-chain length and connectance by the first year following dam removal. These properties increased over time, but did not reach pre-dam removal levels in the Olentangy River. At an actively restored reach, I observed lower species richness and food-chain length than at a nearby passively restored reach in the first year after dam removal followed by no differences in these metrics in the subsequent years of the study. Collectively, my results contribute to disturbance and food-web theory in fluvial systems, and provide important information that can be used to further inform future dam-removal projects.
Advisor: Mazeika Sullivan