Modeling feedbacks between oyster reef growth and sediment dynamics (2014)

Undergraduate: Rachel Housego

Faculty Advisor: Johanna Rosman
Department: Environmental Science

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Sedimentation has been identified as a factor that can limit oyster reef restoration success. Previous field studies have demonstrated that high relief reefs are more productive and resilient to disturbance than low relief reefs, in part because increasing the reef height can reduce sedimentation. In this study we investigated the relationship between initial reef height and reef survival using a simple model. The model, based on Jordan-Cooley et al. (2011), contains three coupled differential equations that describe changes in oyster volume, sediment volume, and shell volume per unit area of reef with time. In our study, the terms for oyster growth, sediment deposition, and erosion were modified from the Jordan-Cooley model to better represent these processes. A sensitivity analysis was then performed to investigate the ways in which parameters such as flow speed, sediment grain size, and ambient food concentration affect model results. Our results suggest that the shape of the sediment concentration profile in the water column relative to the initial reef height is important for determining whether a reef will survive. Parameters that describe oyster growth will control the productivity of the reef and the final reef height, if the reef does survive. Therefore, our study creates a tool that can be used to predict the relative success of restored oyster reefs under different environmental conditions and the impact of different physical parameters on reef restoration success.