Biomechanics of how fish cope with environmental flow and how it influences habitat selection

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Water's physical properties create demands that fishes must overcome to access resources. For example, water's high density and viscosity lead to drag forces that markedly limit a fish's speed and acceleration. Accordingly, a growing body of works suggests that fish body and fin morphology and swimming movement patterns could confer various functional advantages. So, it is hypothesized that some fish species may not be capable of living in habitats for which they lack sufficient mechanical ability, but this has rarely been tested quantitatively. To do so, we need to know how and when different parts of a fish's body generate propulsive forces, but until my recent work in methods development, we have not had the technology to study in detail the forces produced along the bodies and fins of live, freely swimming fishes. My research program focuses on understanding the relationships among fish morphology, body- and fin-use patterns, performance, and habitat occupancy in temperate freshwater systems. These systems range from torrential streams to static lakes, a flow gradient along which fish species and, qualitatively, their forms and swimming movements vary. I propose three short-term objectives that will support the training of 2 PhD, 3 MSc, and 10 undergraduate students: I will 1) describe how much variation there is in swimming forces and capabilities within a species that occurs in both high- and low-flow areas, 2) determine what mechanics allow some fishes to cope with turbulence, the choppy flows resulting from waves and environmental structure, and 3) explore the degree to which swimming mechanics corresponds to fish abundances. To achieve these goals, I will collect fish shape data from museum specimens, build ecological models that link fish shapes and abundances to habitat characteristics, perform physical mechanical studies to link shape and movement to swimming ability, and explore energetic costs of swimming with respirometry. This work advances our understanding of the form-function relationships enabling fishes to live in varied habitats. In turn, this understanding provides potential biomimetic solutions to unmanned underwater vehicles design challenges in environmental monitoring and salvage applications. Current designs are large and noisy; fish-like designs are less disruptive to wildlife and better at maneuvering through complex structures like shipwrecks. More broadly, this work benefits the stewardship of aquatic ecosystems, which have commercial, recreational, and cultural value across Canada. Human development at shoreline, changes to land use, and anthropogenic climate change are dramatically altering flow and turbulence in aquatic systems - e.g., increasing the frequency and intensity of flooding events. An understanding of how fishes interact with flow therefore informs strategic guidelines for shoreline construction and habitat remediation efforts, ultimately contributing to aquaculture and fisheries management.