An official website of the United States government
Abstract Stony coral tissue loss disease (SCTLD) is a widespread and deadly disease that affects nearly half of Caribbean coral species. To understand the microbial community response to this disease, we performed a disease transmission experiment on US Virgin Island (USVI) corals, exposing six species of coral with varying susceptibility to SCTLD. The microbial community of the surface mucus and tissue layers were examined separately using a small subunit ribosomal RNA gene-based sequencing approach, and data were analyzed to identify microbial community shifts following disease acquisition, potential causative pathogens, as well as compare microbiota composition to field-based corals from the USVI and Florida outbreaks. While all species displayed similar microbiome composition with disease acquisition, microbiome similarity patterns differed by both species and mucus or tissue microhabitat. Further, disease exposed but not lesioned corals harbored a mucus microbial community similar to those showing disease signs, suggesting that mucus may serve as an early warning detection for the onset of SCTLD. Like other SCTLD studies in Florida, Rhodobacteraceae, Arcobacteraceae, Desulfovibrionaceae, Peptostreptococcaceae, Fusibacter, Marinifilaceae, and Vibrionaceae dominated diseased corals. This study demonstrates the differential response of the mucus and tissue microorganisms to SCTLD and suggests that mucus microorganisms may be diagnostic for early disease exposure.
more »
« less
Microbial bioindicators of Stony Coral Tissue Loss Disease identified in corals and overlying waters using a rapid field‐based sequencing approach
Summary Stony Coral Tissue Loss Disease (SCTLD) is a devastating disease. Since 2014, it has spread along the entire Florida Reef Tract and into the greater Caribbean. It was first detected in the United States Virgin Islands in January 2019. To more quickly identify microbial bioindicators of disease, we developed a rapid pipeline for microbiome sequencing. Over a span of 10 days we collected, processed and sequenced coral and near‐coral seawater microbiomes from diseased and apparently healthyColpophyllia natans,Montastraea cavernosa,Meandrina meandritesandOrbicella franksi. Analysis of bacterial and archaeal 16S ribosomal RNA gene sequences revealed 25 bioindicator amplicon sequence variants (ASVs) enriched in diseased corals. These bioindicator ASVs were additionally recovered in near‐coral seawater (<5 cm of coral surface), a potential reservoir for pathogens. Phylogenetic analysis of microbial bioindicators with sequences from the Coral Microbiome Database revealed thatVibrio,Arcobacter, Rhizobiaceae and Rhodobacteraceae sequences were related to disease‐associated coral bacteria and lineages novel to corals. Additionally, four ASVs (Algicola,Cohaesibacter,ThalassobiusandVibrio) were matches to microbes previously associated with SCTLD that should be targets for future research. Overall, this work suggests that a rapid sequencing framework paired with specialized databases facilitates identification of microbial disease bioindicators.
more »
« less
- Award ID(s):
- 1946412
- PAR ID:
- 10379329
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Environmental Microbiology
- Volume:
- 24
- Issue:
- 3
- ISSN:
- 1462-2912
- Format(s):
- Medium: X Size: p. 1166-1182
- Size(s):
- p. 1166-1182
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Coral diseases contribute to the rapid decline in coral reefs worldwide, and yet coral bacterial pathogens have proved difficult to identify because 16S rRNA gene surveys typically identify tens to hundreds of disease‐associate bacteria as putative pathogens. An example is white band disease (WBD), which has killed up to 95% of the now‐endangered CaribbeanAcroporacorals since 1979, yet the pathogen is still unknown. The 16S rRNA gene surveys have identified hundreds of WBD‐associated bacterial amplicon sequencing variants (ASVs) from at least nine bacterial families with little consensus across studies. We conducted a multi‐year, multi‐site 16S rRNA gene sequencing comparison of 269 healthy and 143 WBD‐infectedAcropora cervicornisand used machine learning modelling to accurately predict disease outcomes and identify the top ASVs contributing to disease. Our ensemble ML models accurately predicted disease with greater than 97% accuracy and identified 19 disease‐associated ASVs and five healthy‐associated ASVs that were consistently differentially abundant across sampling periods. Using a tank‐based transmission experiment, we tested whether the 19 disease‐associated ASVs met the assumption of a pathogen and identified two pathogenic candidate ASVs—ASV25Cysteiniphilum litoraleand ASV8Vibriosp. to target for future isolation, cultivation, and confirmation of Henle‐Koch's postulate via transmission assays.more » « less
-
Abstract Coral diseases have increased in frequency and intensity around the tropics worldwide. However, in many cases, little is known about their etiology.Montiporawhite syndrome (MWS) is a common disease affecting the coralMontipora capitata, a major reef builder in Hawai'i. ChronicMontiporawhite syndrome (cMWS) is a slow‐moving form of the disease that affectsM. capitatathroughout the year. The effects of this chronic disease on coral immunology and microbiology are currently unknown. In this study, we use prophenoloxidase immune assays and 16S rRNA gene amplicon sequencing to characterize the microbiome and immunological response associated with cMWS. Our results show that immunological and microbiological responses are highly localized. Relative to diseased samples, apparently healthy portions of cMWS corals differed in immune activity and in the relative abundance of microbial taxa. Coral tissues with cMWS showed decreased tyrosinase‐type catecholase and tyrosinase‐type cresolase activity and increased laccase‐type activity. Catecholase and cresolase activity were negatively correlated across all tissue types with microbiome richness. The localized effect of cMWS on coral microbiology and immunology is probably an important reason for the slow progression of the disease. This local confinement may facilitate interventions that focus on localized treatments on tissue types. This study provides an important baseline to understand the interplay between the microbiome and immune system and the mechanisms used by corals to manage chronic microbial perturbations associated with white syndrome.more » « less
-
Summary Coral‐associated microorganisms are thought to play a fundamental role in the health and ecology of corals, but understanding of specific coral–microbial interactions are lacking. In order to create a framework to examine coral–microbial specificity, we integrated and phylogenetically compared 21,100 SSU rRNA gene Sanger‐produced sequences from bacteria and archaea associated with corals from previous studies, and accompanying host, location and publication metadata, to produce the Coral Microbiome Database. From this database, we identified 39 described and candidate phyla of Bacteria and two Archaea phyla associated with corals, demonstrating that corals are one of the most phylogenetically diverse animal microbiomes. Secondly, this new phylogenetic resource shows that certain microorganisms are indeed specific to corals, including evolutionary distinct hosts. Specifically, we identified 2–37 putative monophyletic, coral‐specific sequence clusters within bacterial genera associated with the greatest number of coral species (Vibrio,EndozoicomonasandRuegeria) as well as functionally relevant microbial taxa (“CandidatusAmoebophilus”, “CandidatusNitrosopumilus” and under recognized cyanobacteria). This phylogenetic resource provides a framework for more targeted studies of corals and their specific microbial associates, which is timely given the escalated need to understand the role of the coral microbiome and its adaptability to changing ocean and reef conditions.more » « less
-
Diseases have caused unprecedent mortality in Caribbean coral communities. White band disease (WBD) has killed up to 95% of all endangered Caribbean Acroporids since it was first observed in 1979. Despite the devastating impacts of WBD, its etiology is currently unknown although recent research identified two bacterial strains – ASVs classified as aCysteiniphilum litoraleand aVibriosp., as the most likely pathogens. To better understand the disease etiology of WBD, we pretreated corals with antibiotics to determine how prophylactic use of antibiotics impacts the transmission of WBD in a replicated tank-based experiment. We found the prophylactic use of antibiotics led to significantly reduced infection rates in disease exposed corals with a 30-percentage point decrease in the infection rate. Analyses of 16S rRNA amplicon gene sequencing data in the disease exposed corals demonstrated that antibiotic pretreatment resulted in coral microbiomes which were less speciose and contained relatively fewerVibriospp. than untreated corals, indicating that the benefit of the antibiotic pretreatment was its ability to reduce the relative abundance of intrinsic secondary opportunists and/or opportunistic pathogens suggesting their likely importance to the etiology of WBD. We propose two distinct etiologies involving either an extrinsic keystone pathogen (Cysteiniphilum litorale) or overgrowth of intrinsic opportunistic pathogens (Vibriospp.). Future research should isolate these strains to confirm the etiology of white band disease.more » « less
