Stabilizing coral reef growth with ARKs
Interdisciplinary Capstone Team 26022 is helping sustain Biosphere 2’s delicate ocean ecosystem by improving the growth of coral reefs.
Chris Richards/University Communications
Biosphere 2 researchers study some of the planet’s most complex biomes – from coral reefs to desert plants. This year, four engineering capstone teams are contributing to that work, including Interdisciplinary Capstone Team 26022.
ARKs have a geodesic shape – a lightweight design that helps the structure float midwater.
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Research specialist Lia Crocker asked the team to study the hydrodynamics of coral reef ARKs – structures designed to support the growth and restoration of coral fragments.
“Many restoration efforts focus on simply placing corals back into the ocean, but Wholome Arks has developed a system called ARMS, or Autonomous Reef Monitoring Structures,” said Crocker, a biosystems engineering master’s alumna. “These are placed on the ocean floor and left for years, allowing marine life to naturally colonize them.”
Wholome Arks partners with Biosphere 2 to advance coral reef restoration research and identify the best methods for coral growth. Coral reefs are declining globally. Since 2019, the Global Reef Monitoring Network found that 14% of the world’s corals disappeared, and the Intergovernmental Panel on Climate Change reported in 2018 that reefs could decline 70-90% if global temperatures continue to rise.
Wholome’s ARMS attach to ARKs, which float midwater to protect the new ecosystem.
“When the structures are later incorporated into reef arks, they bring not just the corals, but the broader community of reef organisms with them,” Crocker said.
Coral colonize on ARMS, or Autonomous Reef Monitoring Structures, which attach to ARKs for restoration and long-term growth.
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Facilitating thriving coral life
Water flow is critical to coral health, influencing oxygen levels, nutrient delivery and waste removal. Weak or uneven circulation can limit coral growth.
To address this, the team analyzed how different structural designs affect circulation patterns.
“Our goal is to understand how the structure of the ARK impacts water movement around the coral,” said Yousef Alabiad, mechanical engineering student and team lead. “If we can optimize that flow, it can create a healthier environment for coral growth.”
Using computational fluid dynamics modeling and testing, the team evaluated water velocity, turbulence and circulation inside the structures.
After extensive trial and error, the team developed three potential structures built with PVC plates arranged horizontally and bolted down to serve as an ocean bed for coral.
“Traditional coral reef restoration has about a 42% survival rate after 3 years,” Alabiad said. “Whereas the ARK concepts we are looking at, demonstrate survival rates above 80%.”
The team’s ARKs will undergo further testing and design iteration in the Biosphere 2 Ocean, a 2.6-million-liter coral reef mesocosm whose environment researchers can precisely control.
“We've installed two ARKs already into the Biosphere 2 Ocean, and we have corals on them now,” Crocker said, project adviser. “We plan to add more, but our role is really to use the controlled environment of our facilities to help our capstone team refine and iterate on their designs.”
For Alabiad, a longtime passion for automotive design and aerodynamics made the project an unexpected fit. What drew him in was the chance to apply those same principles in a water-based ecosystem – where engineering curiosity and environmental impact aligned.
“We’re the only capstone team working on an underwater project… and that makes it especially exciting,” Alabiad said.
Watch interdisciplinary capstone teams showcase their work at the Craig M. Berge Design Day on May 4.