LONGITUDINAL STUDY OF STONY CORAL TISSUE LOSS DISEASE AND THE MICROBIOME

Stony coral tissue loss disease (SCTLD) caused dramatic coral declines across the Caribbean and is likely caused by bacteria transmitted via seawater. Thus far, field-based research on SCTLD-affected microbiomes primarily compares healthy and diseased corals from single time points with minimal attention to the seawater microbes. This study is the first longitudinal study of corals contracting SCTLD. From Colpophyllia natans colonies in the U.S. Virgin Islands, tissue and near-coral seawater were sampled on naïve reefs (2020) through the emergence and extent of the SCTLD outbreak (2024). SCTLD prevalence surveys and colony fate tracking were paired with sequencing of the 16S rRNA gene of bacteria and archaea in coral tissue and near-coral seawater. We found that the microbiomes from coral tissue exhibited high beta diversity over time, both within and between colonies, suggesting dysbiosis or disrupted coral health before SCTLD exposure. In contrast, the seawater samples showed a consistent microbial composition, which was disturbed by SCTLD near diseased colonies, and disturbance was most pronounced when the disease was in its epidemic phase in the USVI (2020-2021). When SCTLD entered its endemic phase (2023–2024), the disease caused little disruption in the near-coral seawater of diseased corals. The uniformity of reef water microbes surrounding healthy corals, and the disruption during the SCTLD epidemic, suggests that corals are experiencing environmental stress during disease epidemics, which may enhance disease transmission and disease lethality.

Presentation Preference: Either

Primary Presenter: Jeanne Bloomberg, Woods Hole Oceanographic Institution / Massachusetts Institute of Technology (jeanne.bloomberg@whoi.edu)

Authors:

Cynthia Becker, Ithica College  (cbecker3@ithaca.edu)

Sarai Hutchinson, University of the Virgin Islands  (sarai.hutchinson@students.uvi.edu)

Sonora Meiling, University of the Virgin Islands  (sonora.meiling@uvi.edu)

Marilyn Brandt, University of the Virgin Islands  (mbrandt@uvi.edu)

Amy Apprill, Woods Hole Oceanographic Institution  (aapprill@whoi.edu)