Coral reefs around the world are at risk due to compounding global and local stressors such as overfishing,pollution, thermal bleaching and ocean acidification. Hydrodynamics play a key role in regulating coral health, facilitating intake and removal of metabolic compounds, controlling thermal variability and dispersing coral larvae,for example. Simultaneously, corals also have influence over their environments. A defining feature of reefs is their remarkably large, spatially variable and multi-scaled roughness. Coral roughness produces frictional effects strong enough to balance both wave and tidal forcing, as well as to dissipate incoming wave energy, which provides crucial storm protection to coastal communities.

This dissertation presents results from three years of fieldwork on two adjacent reefs in Palau, where we sought to understand how corals modify their environments both dynamically and chemically. We first examine how turbulence generated by corals mixes momentum and chemicals throughout the water column. The goal of this work is to improve and expand application of non-invasive methods for measuring community production and calcification rates, which are important indicators of reef health. Next, we combine modeling and in-situ observations to explore how larger-scale roughness features known as “spurs and grooves” modify wave properties, energy dissipation and circulation dynamics, and discuss the positive feedbacks that these morphologic features provide for coral resilience. 

Bob and Norma Street Environmental Fluid Mechanics Laboratory, Committee: Stephen Monismith (advisor), Robert Dunbar, Jeffrey
Koseff, Oliver Fringer, Sanjiva Lele (chair)