Coral reefs provide food, shelter, and habitat to thousands of organisms living in the Gulf of Mexico. However, their vulnerability to physical and toxicological damage increases corals’ risk during environmental disturbances, particularly in shallow water where dangers from coastline proximity include wastewater pollution, moving sediment, salinity and nutrient changes, scavengers, and boating and fishing activities.
Much research after Deepwater Horizon focused primarily on community-level impacts to corals in areas affected by the oil spill. A Florida-based science team is looking at individual effects at the coral tissue level and is seeking to improve assessments with more-consistent laboratory exposure methods, oil compounds used, and coral species examined.
Dawn Bickham is a master’s student with Nova Southeastern University’s Department of Marine and Environmental Sciences, and she helps assess the health and recovery of shallow-water corals exposed to oil- and oil plus dispersant mixtures. Her findings will help fill knowledge gaps regarding sublethal oil spill effects on coral systems and help responders determine which aspects of the Gulf are most at-risk when an oil spill occurs.
Dawn is a GoMRI Scholar with the project Coral-Tox: A Species-Sensitivity Assessment of Petroleum Hydrocarbon Toxicity to Scleractinian Corals.
Her Path
Dawn’s journey to biological research took a long and unexpected road. After high school, she entered the United States Air Force as an Operations Resource Manager and later completed an Information Technology undergraduate degree at American InterContinental University’s Florida campus. Shortly after, she began training equestrian riders in Plantation, Florida, and shadowed equestrian industry leaders to acquire nutrition and sports medicine skills to help her clients. She also started diving and snorkeling and joked that if she wasn’t on a horse, she was in the water.
Snorkeling sparked Dawn’s curiosity about coral biology, so she searched for local coral research opportunities and volunteered in Dr. Abigail Renegar’s scleractinian coral biology lab at Nova Southeastern University. She spent more than a decade volunteering in the lab and occasionally attended scientific conferences with Dr. Renegar, which further fueled her captivation with coral research. When a lab position became available, Dawn applied to the university’s biological sciences master’s program and joined Dr. Renegar’s GoMRI-funded coral research team. “My interactions with the oil spill community sparked my interest in oil- and dispersant-related research and cultivated a drive to educate the community about spilled oil’s impacts on our marine resources,” said Dawn. “When the opportunity to work with corals in the scope of oil spill response arose, I was excited to pursue it.”
Her Work
Dawn’s current research began with a previous collaboration between the Renegar lab and government and response community research partners to develop a standardized toxicity testing protocol for adult scleractinian corals (hard corals) that considers how different coral species respond to individual oil compounds. During that effort, the team successfully developed and applied the protocol to one species of shallow-water coral and demonstrated the lethal and sublethal impacts of a single hydrocarbon. The Renegar team is building upon that work by including more coral species and predicting the toxicity of other individual hydrocarbons using the critical body burdens (CBB) – the exposure levels that corals can experience before toxicity occurs, which can cause long-term negative health effects. Their results will help determine thresholds of acceptable/unacceptable impact on corals, help predict impact severity, and inform oil spill responders about the potential impacts of oil and various response methods on corals.
Dawn and her colleagues exposed five ecologically relevant coral species (Acropora cervicornis, Solenastrea bournoni, Stephanocoenia intersepta, Siderastrea siderea, and Porites astreoides) to different hydrocarbon concentrations commonly found in Gulf of Mexico crude oil (toluene, 1-methylnaphthalene, and phenanthrene) for 48 hours using a passive dosing method. They collected growth rate and Pulse-Amplitude-Modulation (PAM) data, which measures the corals’ photosynthetic health (how well it absorbs or reflects light), conducted transcriptomic analyses on the coral’s RNA, and determined CBB using visual assessments of coral condition. These metrics will help determine the concentrations at which each hydrocarbon begins negatively affecting the coral. The team also conducted exposures using increasing concentrations of crude oil to validate findings from the single-hydrocarbon experiment and conducted oil plus dispersant exposures to learn more about effects from dispersant use near coral reefs.
After each exposure treatment, Dawn wounded the corals with a dremel to simulate damage that might occur during response operations (from booms or other mitigation equipment) and took photos at different time points (at time of wound, 1 week after, 1 month after, and 3 months after). She is analyzing approximately 800 photos to determine if there is a correlation between oil concentration and the corals’ ability to repair wounds. Dawn’s team plans to generate a detailed understanding of oil toxicity for each coral species by combining the wound repair data, the PAM data, results from the coral’s RNA transcriptomic analysis, and CBB data from visual coral condition assessments. “All of our metrics are put together to address the big picture of coral health, and the outcome we’re starting to see is that corals may be much more resilient than we expected,” said Dawn.
The team will integrate their results into existing and emerging oil toxicity and 3D oil plume models that will visualize and predict how oil affects corals and inform decisions related to the impact severity of response treatments. “As long as we are using and processing oil, it’s not if we have another oil spill disaster, it’s when,” she said. “When we do our experiments, we want to give responders and industry the best information possible before a spill happens.”
Dawn expressed an interest in exploring the coral’s genetic data to observe if exposure triggered the upregulation or downregulation of any genes that might affect the coral’s ability to recover. She speculates that if the exposure triggered an upregulation of genes that help protect the coral, such as mucus production, there may not be enough energy left for the coral to repair itself when wounded. She hopes that future experiments explore this possibility.
Her Learning
The project’s ambitious experiment schedule required much planning and teamwork, which helped Dawn learn how to function as part of a larger research group. She learned skills in experimental design, workload sharing, and laboratory organization and was able to apply her computer science background to manage the project’s large quantities of data. She found that a big challenge of laboratory research is repeating certain tasks over and over, but she emphasized that it is important to conduct detailed analyses that validate one’s findings. “Completing specific tasks multiple times can cause some people to become complacent in those details,” she said. “We ensured that we maintained the same quality of work through the entire process.”
Dawn is thankful that the GoMRI program helped her expand her horizons and learn new skills. She learned the importance of having an advisor who is understanding, eager to teach, and encourages the use of existing knowledge to gain new knowledge. “I’m coming into this project as a second career and, since I don’t come from a biology background, I’m doing a lot of catch up,” she said. “Working with team members and collaborating with industry people and researchers from other projects has been amazing. I’ve found it a very reassuring place to be.”
Dawn hopes to find a position in industry where she can continue working in toxicology and investigate the sublethal effects of environmental disturbances on marine organisms.
Praise for Dawn
Dr. Renegar reflected on Dawn’s unique background as an Air Force veteran and computer scientist. She explained that Dawn’s experiences have granted her a level of maturity that allows her to mentor her fellow graduate students. Since joining the lab, Dawn has become an integral part of the lab culture and Dr. Renegar praised her eagerness to learn new skills and apply her previous knowledge to coral biology research. “Dawn has learned a great deal since joining the lab,” she said. “I have been very pleased with her progress as a scientist!”
The GoMRI community embraces bright and dedicated students like Dawn Bickham and their important contributions. The GoMRI Scholars Program recognizes graduate students whose work focuses on GoMRI-funded projects and builds community for the next generation of ocean science professionals.
By Stephanie Ellis and Nilde Maggie Dannreuther. Contact sellis@ngi.msstate.edu for questions or comments.
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The Gulf of Mexico Research Initiative (GoMRI) is a 10-year independent research program established to study the effect, and the potential associated impact, of hydrocarbon releases on the environment and public health, as well as to develop improved spill mitigation, oil detection, characterization and remediation technologies. An independent and academic 20-member Research Board makes the funding and research direction decisions to ensure the intellectual quality, effectiveness and academic independence of the GoMRI research. All research data, findings and publications will be made publicly available. The program was established through a $500 million financial commitment from BP. For more information, visit http://gulfresearchinitiative.org/.
© Copyright 2010-2020 Gulf of Mexico Research Initiative (GoMRI) – All Rights Reserved. Redistribution is encouraged with acknowledgement to the Gulf of Mexico Research Initiative (GoMRI). Please credit images and/or videos as done in each article. Questions? Contact web-content editor Nilde “Maggie” Dannreuther, Northern Gulf Institute, Mississippi State University (maggied@ngi.msstate.edu).