Nearly 75 percent of the world’s coral reefs are under threat from rising ocean temperatures and local human activity, said Anne Staples, an associate professor in Virginia Tech’s Department of Biomedical Engineering and Mechanics.
Five hundred million people rely on coral reefs for food, income, and coastal protection, according to the Coral Reef Alliance, a nongovernmental agency in the United States focused on saving coral reefs. The National Oceanic and Atmospheric Administration estimates closer to 1 billion people relying on coral reefs.
However, protecting and understanding this vital resource can be difficult. Corals, which Staples describes as being almost half-plant, half-animal, are composed of branching skeletons covered by a mat of tiny polyp animals. Algae live in the polyps’ tissues and supply the byproducts of photosynthesis. These nutrients, together with those carried to corals by the oceans’ waters, allow the polyps to live. The opacity of densely branched corals makes it difficult to measure flows between their branches, so most coral hydrodynamics research has been conducted above, or at the edges of coral reefs.
Staples, who joined Virginia Tech faculty in 2008, was one of the first researchers to use computational methods to study ocean flows through coral branches. In doing so, she helped provide an answer to the long-standing question of how corals get enough nutrients to sustain the polyps deep in the interior of the reef, where the flow speeds are much lower than at the reef’s edges. Staples’ computations revealed that even though water flow slows down as it moves through the coral – similar to wind slowing as it moves through trees – the mass transfer is the same throughout the reef because the branches stir the flow, allowing the nutrients to reach the polyps at the interior.
“Understanding how ocean flows interact with coral reefs is an important research area because a third of coral species are endangered,” said Staples, the director of research in the Laboratory for Fluid Dynamics in Nature. “Finding that the rate of mass transfer through a reef is constant even though the velocity is reduced was an incredibly rewarding moment in our lab. And further insights into this topic, like a better understanding of how reefs absorb wave energy so effectively, could help protect our shorelines as storms become increasingly frequent and intense and as sea levels rise.”
Coral reefs prevent coastal erosion and serve as a natural flood defense system, lessening the effects of storm surges by absorbing up to 97 percent of storm wave energy. Bioinspired sea walls designed to mimic the structure of coral reefs are friendly to sea life and don’t cause coastal erosion like unnatural barriers that completely block the flow, said Staples. Understanding how coral reefs are so effective at coastal protection could lead to improved sea wall designs.
A dynamic path in fluid flow and mechanics
Staples’ research is not just focused on coral reefs. She earned each of her degrees – a bachelor’s, master’s, and Ph.D. – in mechanical and aerospace engineering. Staples was first drawn to the field of fluid dynamics after attending a class on that topic as an undergraduate student at Cornell University. Her professor, Charles Williamson, taught the students about fluid mechanics from various perspectives. The demonstration that most caught Staples’ attention was a visualization of airflow over a model airplane wing, which clearly revealed the phenomena of turbulence and stall. Stall is when the air flow around a wing separates from the wing surface and lift cannot be generated.
“Seeing this demonstration, I was mesmerized by the beauty of fluids in motion,” said Staples. “That, and the elegance of the mathematics behind fluids phenomena, hooked me. I knew I had found my career path.”
Staples went on to attend graduate school at Princeton University, where she continued to study fluid dynamics and mechanics. In 2002, she won the Amelia Earhart Fellowship from Zonta International for her computational research on turbulence. Established in 1938, the Amelia Earhart Fellowship is for women pursuing advanced degrees in aerospace engineering and space sciences. The award ceremony marked the first time Staples participated in an event specifically for women in STEM, she said.
“Around that time, only 15 percent of my classmates in mechanical engineering were women,” said Staples. “Many of us felt pressure to downplay our femininity as a not-very-effective strategy for fitting in. So being part of an international organization of women in STEM was a revelation. It removed the time and energy usually devoted to questions of belonging and allowed us to focus solely on the engineering topics we were passionate about. That’s part of the reason I’m so intent on improving diversity, equity, and inclusion in our department, at Virginia Tech, and in the broader engineering community. I want everyone to feel welcomed. Everyone who is talented and passionate about STEM belongs and should feel equally at home in engineering settings. If not, we could miss out on important advances in science.”
Computations for diverse applications
Staples has found much success in her career focusing on the fundamentals of computational methods for fluid flows. However, when Virginia Tech’s Department of Engineering Science and Mechanics, the department into which Staples was originally hired, merged with the Department of Biomedical Engineering in 2014, Staples said her research took some notable turns.
Her projects began to involve more experimental work with a focus on medical devices and applications. For example, after modeling the fundamental principles of fluid flows in insect respiratory systems, she created bioinspired microfluidic devices, including an insulin patch for people with diabetes.
Because Staples’ latest research direction is more hands-on, students can join her lab and quickly get started participating in research. This allows Staples to mentor more undergraduate students, fulfilling one of her academic passions. In 2021, Staples mentored 20 undergraduate students in her laboratory through independent research projects and senior design teams.
“Carrying out research on medically focused projects is meaningful and energizing,” said Staples. “It is important to do research on fundamental aspects of engineering, but it doesn’t have the same sense of urgency and importance for me as research that can improve lives in a more direct way. Creating a better insulin patch or improving hemodialysis treatment in a way that has the potential to save lives – that feels directly impactful. Right now, the median survival time once someone begins hemodialysis is just five years. If my lab’s research could extend the median survival time for these patients by even six months, that would be immeasurably valuable.”
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