Florida’s threatened coral reefs have an annual economic impact of more than $ 4 billion on the state’s economy, and researchers at the University of Central Florida are focusing on one factor that could limit their survival: strength of the coral skeleton.
In a new study published in the journal Coral reefs, UCF engineering researchers tested how well staghorn coral skeletons withstand forces of nature and humans, such as impacts from hurricanes and divers.
The researchers subjected the coral skeletons to greater stresses than those caused by ocean waves, says Mahmoud Omer, a doctoral student in the Department of Mechanical and Aerospace Engineering at UCF and co-author of the study. “Under normal wave and tidal regimes, the skeleton of a staghorn coral will resist the physical forces exerted by ocean waves. However, anthropogenic stressors such as harmful ingredients in sunscreen, temperature high ocean levels, pollution and ocean acidification will weaken the coral’s skeleton and reduce its longevity. “
Florida’s coral reefs generate billions of dollars in local income, provide more than 70,000 jobs, protect the state’s coasts from storms and hurricanes, and support a diverse ecosystem of marine organisms, according to the National Oceanic and Atmospheric Administration the United States.
The study discovered a unique safety feature of the staghorn coral skeleton: its porous design prevents the coral from being instantly crushed by an impact.
When UCF engineers subjected skeletal samples to increasing stress, the pores relieved the applied load and temporarily blocked further cracks and structural failures. The pores would “open” and absorb some of the applied mechanical energy, thereby preventing catastrophic failure. Although this ability has been demonstrated in other coral species, this is the first time it has been demonstrated in staghorn coral.
“For the first time, we used the tools of mechanical engineering to take a close look at the skeletons of a critically endangered coral high in a coral nursery,” says John Fauth, associate professor in the biology department of the ‘UCF. “We now know more about the structure and mechanical performance of the staghorn coral skeleton than any other coral in the world. We can apply this knowledge to understand why staghorn coral restoration may work in certain regions, but where their skeletons may work. fail because of man and the environmental challenges in others. “
The results provide benchmarks that can be used to judge whether nursery-reared staghorn corals have skeletons strong enough for nature and to match them to areas with environmental conditions that best match their skeletal strength. .
Staghorn coral gets its name from the wooden shape of its branches, which creates a complex underwater habitat for fish and reef organisms. It is mainly found in the shallow waters around the Florida Keys, Puerto Rico, the US Virgin Islands, and other Caribbean islands, but has declined by over 97% since the 1980s.
Although restoration efforts using transplanted and nursery-reared corals are underway, scientists continue to work to increase their success rate.
Understanding coral skeletal structures could also inform the development of skeletal structure replacements for humans, says Nina Orlovskaya, associate professor in the Department of Mechanical and Aerospace Engineering at UCF. “Our results are of great importance for the development of new and superior biostructures, which can be used as bone graft substitutes,” Orlovskaya said. “The structures of the coral skeleton could be either chemically converted or 3D printed in biocompatible calcium phosphate ceramics that could one day be directly used to regenerate bones in humans.”
In addition to the compression tests, the researchers analyzed the mechanical properties and the spectral and fluidic behavior. The spectral analysis used Raman microscopy, which allowed researchers to map the effects of compression at the microscopic level in the coral skeleton.
Analysis of the fluidic behavior revealed that the eddies formed around the coral colony helped it capture food and transport respiratory gases and wastes.
The coral skeletons studied came from the coral nursery at Nova Southeastern University, about a mile off the coast of Fort. Lauderdale, near Broward County, Florida. The corals were dead and came from colonies that failed or broke off in a storm.
The co-authors of the study also included Alejandro Carrasco-Pena, a graduate of UCF’s mechanical engineering doctoral program; Bridget Masa, a graduate of UCF’s Bachelor of Mechanical Engineering program; Zachary Shepard, graduate of UCF’s Bachelor of Mechanical Engineering program; Tyler Scofield, graduate of UCF’s master’s and bachelor’s degree program in mechanical engineering; Samik Bhattacharya, Assistant Professor in the Mechanical and Aerospace Engineering Department at UCF; Boyce E. Collins, mechanical and chemical engineering scientist at North Carolina A&T State University; Sergey N. Yarmolenko, senior researcher at North Carolina A&T State University; Jagannathan Sankar, Distinguished University Professor at North Carolina A&T State University; Ghatu Subhash, Ebaugh professor in the Department of Mechanical and Aerospace Engineering at the University of Florida; and David S. Gilliam, associate professor at Nova Southeastern University.
The research was funded in part by the National Science Foundation and the US Environmental Protection Agency.
Orlovskaya received her doctorate in materials science from the Institute of Materials Science Problems of the Ukrainian National Academy of Sciences in Kiev. She joined UCF in 2006.
Fauth received his doctorate in zoology from Duke University and joined UCF in 2003.