Changing Stony Coral Tissue Loss Disease Dynamics Through Time in Montastraea cavernosa

Abstract

Stony coral tissue loss disease (SCTLD) is affecting corals across the Western Atlantic and displays species-specific and regional differences in prevalence, incidence, degree of mortality, and lesion morphology. We examined two Florida sites with different temporal histories of disease emergence; Fort Lauderdale where SCTLD is endemic and the Lower Florida Keys where SCTLD has recently emerged. Our objectives were to (1) assess the potential impact of SCTLD on overall reef condition by surveying reefs in each region, (2) in a single common species, Montastraea cavernosa, examine differences in SCTLD prevalence, colony mortality, and lesion morphology in each region, and (3) look for differences in contagion by conducting transmission experiments using lesions from each region. Reef surveys found sites in both regions had low coral cover, high algae cover, and similar coral species composition. SCTLD prevalence was higher in the Lower Keys than at Fort Lauderdale and two of the common species, M. cavernosa and S. siderea at Fort Lauderdale were dominated by smaller colonies (<5 cm) whereas larger colonies occurred in the Lower Keys. Tagged M. cavernosa SCTLD-affected colonies were followed for 2 years at one site in each region. In both years, Fort Lauderdale colonies showed declining disease prevalence, low colony mortality, and disease lesions were mainly bleached spots lacking tissue loss. In contrast, Lower Keys colonies tagged in the first year maintained 100% disease prevalence with high mortality, and disease lesions were predominantly tissue loss with no bleached edges. However, SCTLD dynamics changed, with year two tagged colonies showing declining disease prevalence, low mortality, and lesion morphology switched to a mixture of bleached polyps and tissue loss with or without bleached edges. Lesion morphology on colonies was a significant predictor of amount of tissue loss. Aquaria studies found the rate of SCTLD transmission using lesions from the different zones (emergent and endemic) were similar. Our study highlights that differences in coral mortality from SCTLD are not necessarily linked to host species, lesion morphology is reflective of subsequent rate of mortality, and disease dynamics change through time on reefs where the disease has newly emerged.

Tissue loss disease outbreak significantly alters the Southeast Florida stony coral assemblage

“…Current studies show that SCTLD is most likely a waterborne, bacterial infection, also shown to transmit through direct contact (Aeby et al, 2019;Meyer et al, 2019;Sharp et al, 2020;Ushijima et al, 2020;Shilling et al, 2021). However, there is evidence that SCTLD disease dynamics change through time (Aeby et al, 2021). It is unclear if these small, susceptible species colonies have reduced susceptibility or if the environmental conditions have changed, changing the likelihood of a SCTLD infection and allowing for continued growth.…”

“…SCTLD differs from previously documented white diseases in that lesions may appear in the middle of the colony as opposed to lesions starting at tissue margins or the base of colony; where lesions can be surrounded by bleached tissue and often presents with varying levels of recent tissue necrosis (NOAA Stony Coral Tissue Loss Disease Case Definition, 2018; Landsberg et al, 2020;Aeby et al, 2021). Over 20 species may be susceptible to SCTLD to varying degrees leading to species being categorized as highly susceptible, intermediately susceptible, low susceptible, and presumed susceptible (NOAA Stony Coral Tissue Loss Disease Case Definition, 2018; Dobbelaere et al, 2020).…”

Effect of species, size, and chimerism on the susceptibility of Caribbean brain coral recruits to stony coral tissue loss disease (SCTLD)

“…Other SCTLD-susceptible species, such as Orbicella faveolata and Montastraea cavernosa , are major reef-builders throughout Florida and the Caribbean and are the target of reef restoration efforts using sexually-produced recruits. As such, juveniles of these species should be tested for rates of infection and tissue loss to assess the risk of SCTLD when outplanted in areas where it is endemic or emergent (Aeby et al, 2021). Since adult colonies of different species exhibit variation in their immunocompetency (Palmer et al, 2011) and rates of lesion progression (Meiling et al, 2021), they may also show varied responses to SCTLD as juveniles.…”

Evaluating stony coral tissue loss disease intervention success through whole-transcriptome gene expression profiling

“…Since its first observation near Miami, Florida in 2014, stony coral tissue loss disease (SCTLD) has spread throughout Florida's Coral Reef and to at least 25 jurisdictions across the wider Tropical Western Atlantic (Kramer et al, 2019;NOAA, 2018;Precht et al, 2016). The disease affects at least 24 scleractinian species and is characterized by subacute to acute tissue loss leading to colony mortality, often with formation of rapidly-progressing focal or multifocal lesions (G. Aeby et al, 2021; G. S. Aeby et al, 2019;Landsberg et al, 2020;NOAA, 2018). The pathogen (s) have not yet been identified, though examination of microbiomes of diseased samples suggest a bacterial (Becker et al, 2021;Meiling et al, 2021;Meyer et al, 2019;Rosales et al, 2020Rosales et al, , 2022Studivan et al, 2022;Ushijima et al, 2020) and/or viral (Veglia et al, 2022;Work et al, 2021) consortium.…”