Keywords

Oyster Reefs, Hydrodynamics, Turbulence, Canopy Density

Abstract

Oysters are ecosystem engineers that shape coastal aquatic environments through hydrodynamic influence, which is governed by the reef structure. Hydrodynamic studies have investigated effects of oyster reefs as whole systems, overlooking the spatial variability inherent in canopy structures. In this research, a field investigation was undertaken to characterize spatial variability of flow dynamics within a single eastern oyster (Crassostrea virginica) reef and query how the local canopy density influences the hydrodynamic environment. High-resolution flow measurements were taken within and above the oyster canopy over a range of flow conditions. Hydrodynamics were compared across reef locations as the oyster canopy density increased from sparse to very dense. Unique hydrodynamic behaviors were observed within and above all canopies. For example, flow attenuation was more complete within the canopy (70%-99% attenuation of incident flows) as compared to above (48%-65%). Canopies consisting of moderately dense to dense clusters of oysters exhibited similar hydrodynamic behaviors, characterized by high levels of flow attenuation (64%-97%) and turbulent mixing (mean turbulence intensity up to 30 times the shear velocity). Locations with sparse canopy density and the greatest density, where oysters were packed homogeneously rather than clustered, also greatly attenuated flows (70%-99% attenuation of incident flows) but were characterized by lower turbulent mixing (mean turbulence intensity 1-5 times the shear velocity). Flow augmentation (60% increase in flow speed relative to incident flow) was observed only above the homogeneously dense canopy, indicating development of a shear layer above the canopy. Quadrant analysis revealed that turbulent patterns observed in the vicinity of the homogeneous dense canopy were relatively orderly as compared to the sparse, moderately dense, and dense clustered canopies. Study findings quantify hydrodynamic variability found within natural intertidal oyster reefs, with applications to the design of reef-based natural infrastructure and prediction of how reefs may affect flow and sediment transport.

Completion Date

2024

Semester

Spring

Committee Chair

Kibler, Kelly

Degree

Master of Science in Civil Engineering (M.S.C.E.)

College

College of Engineering and Computer Science

Department

Civil, Environmental and Construction Engineering

Degree Program

Water Resources Engineering

Format

application/pdf

Language

English

Rights

In copyright

Release Date

November 2024

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Campus Location

Orlando (Main) Campus

Accessibility Status

Meets minimum standards for ETDs/HUTs

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