Would you be surprised to know that coral polyps- the tiny animals responsible for building reef structures- are clear? The brilliant colors you see are actually produced by tiny algae (zooxanthellae) which live inside the coral tissue.
In addition to the zooxanthellae, bacteria and viruses also live in coral and collectively form the coral microbiome.
Acting as a foundation species, healthy corals sustain entire reef ecosystems that are believed to have the highest biodiversity of any ecosystem on the planet- even more than a tropical rainforest.
Like all animals though, corals can be affected by disease.
A 2016 National Science Foundation Graduate Research Fellow and doctoral candidate studying Environmental Health at the College of Public Health, Maite Ghazaleh Bucher researches the microbiome of corals in the Florida Keys to better understand the mechanisms driving disease.
According to the Great Barrier Reef Marine Park Authority, disease in coral “may be caused by infections from microbes such as bacteria or viruses or by external stressors including extreme temperatures, toxins, and excess nutrients like nitrogen and phosphorous.”
Over a 21-day period in summer 2016, Bucher and her lab- led by her advisor Dr. Erin Lipp- collected daily coral mucus samples using while SCUBA diving off the Florida Keys.
They also tracked the nutrient influx from Saharan dust that made its way across the Atlantic and settled in the Florida Keys waters.
Because of its high nutrient content, bacteria thrive when dust from the Sahara enters the ecosystem.
Back in the lab, Bucher isolated the bacterial DNA to identify the bacteria present before, during, and after the Saharan dust nutrient pulses.
“Our preliminary data shows that while the coral microbiomes are stable over time, some bacteria, such as potentially pathogenic Vibrio, bloom when dust concentrations are elevated,” comments Bucher. “These bacterial blooms could disrupt the stability of coral microbiomes, leading to disease development.”
Bucher (along with Lipp and Jason Westrich, a post-doctoral student in Microbiology) collected additional data in the Florida Keys during the summer of 2017, this time happening upon a multi-species, multi-disease outbreak.
“We collected over 50 samples of coral species with various diseases (such as white plague, yellow band, and dark spots) with matching samples of nearby healthy coral,” she explains. “We also isolated the bacterial DNA for these samples, and our preliminary results suggest that diseased coral microbiomes vary more in composition and are less stable than healthy coral microbiomes.”
In addition to her academic goals, Bucher co-founded the Scientific Research & Education Network (SciREN) in Georgia with Ruth Wangia (doctoral candidate in Environmental Health Science) and Courtney Thomas (who received her Master’s in Marine Science at UGA).
This non-profit organization aims to bring research into local K-12 classrooms by connecting K-12 educators to UGA’s researchers. Last year, more than 80 researchers and K-12 educators attended events through the organization.
“It is very important that researchers have an avenue to share their knowledge with both local teachers and K-12 students. SciREN is a great way to inspire the general public through learning,” she adds.
After graduation, Bucher plans to complete a post-doc with a lab that balances research, science communication, and teaching in the marine science context.
“Understanding how marine microbiomes change in response to environmental stress or disease allows us to predict and prevent the decline of marine ecosystem health,” she says.