Master of Science (MS)
Semester of Degree Completion
Decades of anthropogenic pressure have devastated lotic ecosystems across the riverscapes of North America, resulting in degradation of critical habitat and contributing to sharp declines in biotic integrity. In response, local stream restoration projects have increased in frequency. However, little effort has been allocated to monitoring and project success has been limited. In addition, restoration projects typically focus on ecological effects above the population-level, while relationships with physiological processes are seldom assessed. Lessons from the long-term restoration and ecological monitoring of Kickapoo Creek highlight some of the complex dynamics driving reach-scale restoration projects. Following instream restoration, I predicted that alterations to critical habitat would stimulate community-level biotic response and increases in biotic integrity. Further, shifts in ecology and distribution of fish following restoration would be linked to the energetic costs associated with navigating complex flows. To examine the relationships between community dissimilarity and habitat alteration, seven 200 m reaches were monitored annually during a seven-year study period. Using barge electrofishing surveys and a Qualitative Habitat Evaluation Index, I investigated distribution patterns of fishes along a gradient of habitat conditions. Following implementation of artificial riffles, rip-rap, scouring keys, and riparian vegetation I observed distinct temporal and spatial shifts in fish community structure. While biotic integrity remained in moderately low condition in reference assemblages, monitoring in restored reaches depicted a delayed temporal response to restoration. In restored sites biotic integrity was positively linked to additional instream habitat and altered channel morphology. Larger substrate sizes, submerged terrestrial vegetation, and deep scour pools reduced siltation and provided necessary refuge to facilitate long-term recovery of degraded fish communities. To better understand the relationships between stream habitat, altered flows, and energetic costs, I measured metabolic oxygen consumption in Longear Sunfish, Lepomis megalotis, swimming in turbulent flow. Fish swam in two flow regimes: quasi-laminar (control), and turbulence simulated by three vertical streets of vortices. Fish were adversely affected by turbulent vortices, and consumed on average 24.8% more oxygen in altered flows. Longear Sunfish also responded strongly to habitat alteration in Kickapoo Creek. Significant regression models linked abundance of Longear Sunfish with deep, slow-moving silt-bottom channels with abundant boulders and submerged vegetation. Ecomorphological models for Longear Sunfish suggest that increased metabolic demands associated with navigating complex turbulent flows may help explain habitat use and behavior. I highlight the need for more comprehensive assessment of restoration efforts. I also demonstrate the ability to use structural restoration as an effective management tool to mitigate loss of biotic integrity. Future work should include long-term continuous temporal and spatial reference monitoring combined with comprehensive ecomorphological models to accurately assess the effects of instream restoration.
Favata, Carl Anthony, "Effects of Habitat Alteration on Ecomorphology of Fish Communities in a Restored Stream" (2016). Masters Theses. 2456.