Could the butterfly effect - in which a small change in one state of a system can result in large differences in a later state - also apply to the earth’s oceans, as well as its skies?
Some species of zooplankton are on the order of one millimeter, but don’t let their size fool you. It’s possible these small creatures can create quite a wave.
While it’s long been understood that large marine animals, like fish or whales, can stir up the ocean’s water columns, the impact of smaller swimmers has remained unclear. Lei Fang, assistant professor of civil and environmental engineering at the University of Pittsburgh Swanson School of Engineering, received a $259,994 award from the National Science Foundation (NSF) to determine how small marine creatures, such as zooplankton, generate turbulence in the ocean and influence global ocean mixing. This mixing plays a vital role in nutrient distribution, the ocean’s carbon cycle, and the Earth’s climate.
"We know that marine organisms play an important role in mixing the ocean, but there’s a gap in understanding how small a creature can be and still contribute to this process," said Fang. "By identifying the smallest size at which marine swimmers can generate turbulence, we aim to improve climate models and ocean simulations that are used to predict everything from nutrient flow to the impacts of climate change."
A New Wave of Discovery
The research team will employ a combination of controlled lab experiments and high-powered computer simulations to replicate the conditions in the ocean and measure how small creatures create turbulence. They’ll focus on factors like a swimmer’s size, movement patterns, and the strength of ocean currents' interaction to generate turbulence. Their goal is to refine the models used to predict ocean behavior and improve large-scale climate simulations.
The findings could have far-reaching implications. In addition to improving climate models, the study could inform the design of more efficient autonomous underwater vehicles, improve aquaculture practices and enhance our understanding of ocean ecosystems.
Next Steps and Broader Impact
This research is set to impact multiple scientific disciplines, from oceanography to engineering. The team’s work is expected to contribute to international efforts in climate change research and will provide valuable data for large-scale ocean simulation tools like the Regional Ocean Modeling System (ROMS).
The three-year project, “How Small Is Too Small? On the Minimum Swimmer Size Required to Generate Sustained Biogenic Turbulence,” began in July 2024.