FGBNMS Coral Disease-1of2

In late August of 2022, an unidentified multi-species acute tissue loss disease with signs and species susceptibility characteristics reminiscent of SCTLD and/or white plague was documented at East and West Bank in the Flower Garden Banks National Marine Sanctuary (FGBNMS, northwest GoM) by NOAA divers. Regardless of its etiology, the recent surveys performed at FGBNMS by NOAA staff identified what is the initial incidence area of a disease that will likely have significant impacts and possibly become widespread across the GoM. This offers an unprecedented opportunity to test hypotheses about the influence of coral community composition and pathogen dispersal on disease spread during the early stages of an outbreak that could profoundly change the diversity of GoM reefs. Given the isolation and high coral density of northwest GoM reefs, studying this outbreak in early stages will enable parsing of the impacts of reef-scale community composition versus seascape-scale dispersal in disease transmission and persistence. We hypothesize that 1) the abundance of highly susceptible species will dictate the initial spread of disease within reef sites. 2) We can determine the minimum pathogenic period of dispersing infectious material, if it is assumed these remote reefs were infected through disease dispersal via hydrodynamics. Furthermore, 3) filamentous viruses that infect Symbiodiniaceae are associated with disease-affected corals, as well as near-reef water (within 1m of reef bottom) on disease-affected reefs and the waste products of a coral predator (the fireworm, Hermodice carunculata), and 4) filamentous virus infections are detectable in Symbiodiniaceae within the genera Breviolum, Cladocopium and Durusdinium. To test these hypotheses, we will 1) identify strategic reef locations for disease surveillance on West and/or East Bank and contribute to the collection and generation of photomosaics in sampling areas to facilitate fate tracking. The abundance of high, moderate and low susceptibility species at West and/or East Bank will be extracted from these photomosaics and used to inform 2) a model we are building for disease spread. This model for FGB will be additionally informed by models of pelagic larval and material dispersal in the GoM and a model of SCTLD spread for USVI shallow and deep reefs. We will additionally aim to 3) and 4) sample Pseudodiploria strigosa, Orbicella franksi, and Porites astreoides (species with high, moderate, and low susceptibility, respectively, to SCTLD, n = 8 colony pairs per species). For each colony pair, we will sample disease lesion (DL) and apparently healthy tissue on a diseased colony (DH), as well as tissue from an apparently healthy colony (HH, n = 3 samples per colony pair) at two time points. Microbial communities from near-reef water, sediments and fireworms will be sampled when possible, with a goal of at least n = 8 per sample type. In culmination, our study will contribute to understanding the etiology of the disease and to a generalizable model that can predict the impact of disease spread and treatment on reefs based on coral species assemblages and seascape connectivity. This work will additionally clarify the role of viruses in coral disease on a high coral cover reef.