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Newly Published Coral Reef Study Examines Disease Resistance

Researchers Under the Sea

Read the Paper at Nature.com | Mydlarz Lab Online

Biologists at The University of Texas at Arlington have published a new study which shows that a coral reef’s tolerance for overall microbial imbalance when challenged with white plague disease reflects the coral’s overall disease resistance.

The paper is the result of research done by Laura Mydlarz, professor of biology and associate dean of the College of Science, and current and former members of her laboratory group, in collaboration with colleagues at the University of the Virgin Islands in St. Thomas, V.I., The Nature Conservancy, and Mote Marine Laboratory in Sarasota, Florida.

Coral species have suffered severe declines due to disease outbreaks. Coral species vary in their susceptibility to disease, but the reasons for this were not previously understood. The new research provides beneficial insights into the comparative understanding of susceptibility among coral species that could help predict disease impacts on coral communities.

The new study, titled “Microbial dysbiosis reflects disease resistance in diverse coral species,” was published in the June 3, 2021 edition of the Nature online journal Communications Biology. Nicholas MacKnight, a fourth-year doctoral student in Mydlarz’s lab, is lead author.

In coral communities, microbial dysbiosis is an unhealthy, disrupted state of imbalance in the holobiont, or the coral host and its associated microbiome. In this study, the researchers transmitted white plague disease to seven diverse Caribbean coral species in a controlled setting. White plague disease is one of the most destructive diseases in the Caribbean and has been devastating Caribbean coral species since the 1970s.

Disease incidence and lesion progression rates were evaluated over a seven-day exposure. Coral microbiomes were sampled after lesion appearance or at the end of the experiment if no disease signs appeared.

“Including these seven species is valuable because they represent diverse ecological contributions that define a coral reef,” MacKnight said. “The disease resistance was variable between the seven coral species, and this study provides insight into which coral species will survive the increased disease threats and who will redefine the changing coral ecosystems.

“We found that the spectrum of disease resistance is reflected in the coral’s tolerance for microbial dysbiosis, or overall microbial imbalance, when challenged with white plague disease.”

The different species exhibited a spectrum of disease susceptibility and associated mortality that corresponded with their tolerances to microbial change, indicating that coral disease and microbial dysbiosis may ultimately shape reef ecosystems, the team noted.

“Coral disease is evolving past the ‘one-pathogen, one-disease’ hypothesis when investigating disease etiology,” MacKnight said. “Recent investigations have considered microbial shifts, or dysbiosis, as being an etiological source. In this study we were able to actually put a number to that dysbiosis and see that it is reflective in the host’s disease resistance.”

The paper’s co-authors include Bradford Dimos, UTA doctoral student in biology; Lauren Fuess, an assistant professor of biology at Texas State University who earned a Ph.D. at UTA in 2018; Contessa Ricci, a researcher at the University of North Texas Health Science Center who earned a Ph.D. at UTA in 2019; and Caleb Butler, a doctoral student at Penn State University who earned a B.S. degree from UTA in 2020.

“This paper makes important contributions to our knowledge of how variations in coral immune response can affect coral communities,” Mydlarz said. “I’m proud that so many members of my lab took part in this research and are co-authors of the paper. This project is particularly noteworthy for Nicholas since it’s his first publication as lead author.”

Additional co-authors include Marilyn Brandt, Kathryn Cobleigh, Danielle Lasseigne, Andia Chaves-Fonnegra, and Jendahye Antoine, all from the University of the Virgin Islands; Alexandra Gutting of The Nature Conservancy in Dallas; and Erinn Muller of Mote Marine Laboratory.

“The increasing prevalence and severity of diseases affect coral species differently,” the team wrote in its new publication. “Because the functional contributions of these species define a reef, it is integral to understand variability in disease susceptibility among coral species to predict how the disease will shape coral reefs of the future.”

The study is based on research conducted through funding from the National Science Foundation’s Division of Ocean Sciences. Mydlarz is principal investigator for the two-year, $220,331 grant, which was awarded in 2017.