Stony Coral Tissue Loss Disease – Investigating Possible Pathogens and Transmission Mechanisms
Stony Coral Tissue Loss Disease
Coral disease was first documented on Florida reefs in the 1970s. Since then, outbreaks of diseases have increased, and disease is now one major reason why coral reefs worldwide are in decline. Although what causes most coral diseases is not known, the few with known causes have been linked to microorganisms, highlighting the need for studies of microbes associated with diseased corals.
What Is Stony Coral Tissue Loss Disease (SCTLD)?
In 2014, a new coral disease known as stony coral tissue loss disease, or SCTLD, appeared off the coast of Miami, Florida. This highly devastating disease is characterized by rapidly progressing lesions that can result in full coral colony mortality in a matter of weeks if corals don’t receive treatment. More than 20 different species of stony corals (those with hard skeletons) are known to be susceptible to this disease, including numerous species listed as threatened under the U.S. Endangered Species Act and important reef-builders. Today, the disease has spread throughout the entire Florida Reef Tract and across the Caribbean, leaving a trail of devastation in its wake -- on some reefs, some of the most vulnerable coral species have lost more than 95% of their pre-SCTLD populations.
![two photos of same coral. Left coral mostly covered in live tissue, with dead section. Right photo: dead coral covered in algae](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/thumbnails/image/B%2BA_SCTLD.png?itok=0uzZSC-u)
What Causes SCTLD?
Although the causative agent(s) of SCTLD remains unknown, scientists suspect microbes are involved. One complication is that corals, even healthy ones, naturally host complex and highly diverse microbial communities. This creates complicating “background noise” when trying to pinpoint a microbial cause of a disease. To overcome this complication, we have developed a different method to narrow down the “suspect pool” of possible causes of SCTLD.
Scientists have demonstrated that SCTLD can spread from infected corals to healthy corals placed in the same water (“waterborne transmission”), indicating that the causative agent is shed by the infected corals into the surrounding environment. By placing SCTLD-infected corals in mesocosms (small experimental environments) containing sterilized seawater (seawater treated to remove most microorganisms), any microbes later found in this water will be those that have been shed by the infected coral, including SCTLD’s causative agent(s).
![Two pieces of coral sit in separate buckets with seawater. The left coral is healthy. The right coral has a tissue lesion.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/media/images/sctld.png?itok=EQ3Dg7NR)
We also do not know how much of the causative agent(s) a healthy coral must be exposed to before they become sick – this is called the infectious dose. To overcome this unknown, our method uses tangential flow filtration, or TFF, a method of filtering which essentially removes the water from the mesocosms, leaving behind a highly concentrated version of the microbial community that we can analyze.
![A woman wearing purple gloves sits on a cooler with a hose and a white bucket in a laboratory](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/Seminar_Poster_Kellogg-11-15-2021.jpg?itok=Ddj7SteA)
Because different types of microorganisms (for example, bacteria, viruses, etc) generally have different sizes, following TFF-concentration, our method next utilizes size fractionation – passing the TFF-concentrated coral mesocosm microbial communities through a sequential series of filters with different size openings (“pores”) to separate out these different-sized microbial groups.
![Three funnels, each containing a filter and seawater, rest in a manifold](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/filtration.jpg?itok=LhIksU5a)
As an extension of our method, to help determine which microbial group is responsible for SCTLD, we have also tested attaching these filters to healthy coral fragments and monitoring for the appearance of SCTLD symptoms.
![A diagram with arrows depicting the movement of microbes through tangential flow filtration and sequential filtration steps.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/method.jpeg?itok=WoBy0av-)
How Has SCTLD Spread?
In addition to the identity of the causative agent(s), other unknowns surrounding SCTLD include how the disease has managed to spread so rapidly and so sporadically. In the Caribbean, for example, SCTLD outbreaks often popped up in seemingly random locations, suggesting the disease was not spreading via movement of natural water currents. Instead, these outbreaks often occurred near major ports, suggesting that ships may serve as vectors for the disease. However, the mechanisms by which this may occur remain unclear. One possibility is that SCTLD pathogen(s) may enter new areas attached to ships as biofilms (complex communities of microorganisms that form on submerged surfaces). Our work with Project MERMAID. revealed that biofilms formed on stainless steel in association with SCTLD-infected corals carried microbial signatures of the disease.
Coral Microbial Ecology
Measuring Coral Growth to Help Restore Reefs
Coral Disease
Prokaryotic Communities Shed by Diseased and Healthy Coral (Diploria labyrinthiformis, Pseudodiploria strigosa, Montastraea cavernosa, Colpophyllia natans, and Orbicella faveolata) into Filtered Seawater Mesocosms - Raw and Processed Data
The files in this data release are those referenced in the journal article by Evans and others (2023) entitled 'Investigating microbial size classes associated with the transmission of stony coral tissue loss disease (SCTLD)'. The files contain an amplicon sequence variant (ASV) table and the raw 16S rRNA gene amplicon files from fifty-six 0.22-micrometer (µm) pore size filters, as well as six rea
Prokaryotic Communities From Marine Biofilms Formed on Stainless Steel Plates in Coral Mesocosms - Raw and Processed Data
The files in this data release are those referenced in the journal article by Evans and others (2022) entitled "Ship Biofilms as Potential Reservoirs of Stony Coral Tissue Loss Disease." They contain an amplicon sequence variant (ASV) table and the raw 16S ribosomal ribonucleic acid (rRNA) gene amplicon deoxyribonucleic acid (DNA) sequence files from 15 microbial communities (sample names: CnD16B,
Bacterial Communities Shed by Montastraea cavernosa Coral Fragments into Filtered Seawater Mesocosms-Raw Data
Investigating microbial size classes associated with the transmission of stony coral tissue loss disease (SCTLD)
Effective treatment and prevention of any disease necessitates knowledge of the causative agent, yet the causative agents of most coral diseases remain unknown, in part due to the difficulty of distinguishing the pathogenic microbe(s) among the complex microbial backdrop of coral hosts. Stony coral tissue loss disease (SCTLD) is a particularly destructive disease of unknown etiology, capable of tr
Rapid prototyping for quantifying belief weights of competing hypotheses about emergent diseases
A meta-analysis of the stony coral tissue loss disease microbiome finds key bacteria in unaffected and lesion tissue in diseased colonies
Stony coral tissue loss disease (SCTLD) has been causing significant whole colony mortality on reefs in Florida and the Caribbean. The cause of SCTLD remains unknown, with the limited concurrence of SCTLD-associated bacteria among studies. We conducted a meta-analysis of 16S ribosomal RNA gene datasets generated by 16 field and laboratory SCTLD studies to find consistent bacteria associated with S
Biofilms as potential reservoirs of stony coral tissue loss disease
Since 2014, corals throughout Florida’s Coral Reef have been plagued by an epizootic of unknown etiology, colloquially termed stony coral tissue loss disease (SCTLD). Although in Florida the movement of this waterborne coral disease has been consistent with natural transport via water currents, outbreaks in the Caribbean have been more sporadic, with infections occurring in locations inconsistent
Combining tangential flow filtration and size fractionation of mesocosm water as a method for the investigation of waterborne coral diseases
Coral disease was first documented on Florida reefs in the 1970s. Since then, outbreaks of diseases have increased, and disease is now one major reason why coral reefs worldwide are in decline. Although what causes most coral diseases is not known, the few with known causes have been linked to microorganisms, highlighting the need for studies of microbes associated with diseased corals.
What Is Stony Coral Tissue Loss Disease (SCTLD)?
In 2014, a new coral disease known as stony coral tissue loss disease, or SCTLD, appeared off the coast of Miami, Florida. This highly devastating disease is characterized by rapidly progressing lesions that can result in full coral colony mortality in a matter of weeks if corals don’t receive treatment. More than 20 different species of stony corals (those with hard skeletons) are known to be susceptible to this disease, including numerous species listed as threatened under the U.S. Endangered Species Act and important reef-builders. Today, the disease has spread throughout the entire Florida Reef Tract and across the Caribbean, leaving a trail of devastation in its wake -- on some reefs, some of the most vulnerable coral species have lost more than 95% of their pre-SCTLD populations.
![two photos of same coral. Left coral mostly covered in live tissue, with dead section. Right photo: dead coral covered in algae](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/thumbnails/image/B%2BA_SCTLD.png?itok=0uzZSC-u)
What Causes SCTLD?
Although the causative agent(s) of SCTLD remains unknown, scientists suspect microbes are involved. One complication is that corals, even healthy ones, naturally host complex and highly diverse microbial communities. This creates complicating “background noise” when trying to pinpoint a microbial cause of a disease. To overcome this complication, we have developed a different method to narrow down the “suspect pool” of possible causes of SCTLD.
Scientists have demonstrated that SCTLD can spread from infected corals to healthy corals placed in the same water (“waterborne transmission”), indicating that the causative agent is shed by the infected corals into the surrounding environment. By placing SCTLD-infected corals in mesocosms (small experimental environments) containing sterilized seawater (seawater treated to remove most microorganisms), any microbes later found in this water will be those that have been shed by the infected coral, including SCTLD’s causative agent(s).
![Two pieces of coral sit in separate buckets with seawater. The left coral is healthy. The right coral has a tissue lesion.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/media/images/sctld.png?itok=EQ3Dg7NR)
We also do not know how much of the causative agent(s) a healthy coral must be exposed to before they become sick – this is called the infectious dose. To overcome this unknown, our method uses tangential flow filtration, or TFF, a method of filtering which essentially removes the water from the mesocosms, leaving behind a highly concentrated version of the microbial community that we can analyze.
![A woman wearing purple gloves sits on a cooler with a hose and a white bucket in a laboratory](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/Seminar_Poster_Kellogg-11-15-2021.jpg?itok=Ddj7SteA)
Because different types of microorganisms (for example, bacteria, viruses, etc) generally have different sizes, following TFF-concentration, our method next utilizes size fractionation – passing the TFF-concentrated coral mesocosm microbial communities through a sequential series of filters with different size openings (“pores”) to separate out these different-sized microbial groups.
![Three funnels, each containing a filter and seawater, rest in a manifold](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/filtration.jpg?itok=LhIksU5a)
As an extension of our method, to help determine which microbial group is responsible for SCTLD, we have also tested attaching these filters to healthy coral fragments and monitoring for the appearance of SCTLD symptoms.
![A diagram with arrows depicting the movement of microbes through tangential flow filtration and sequential filtration steps.](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/half_width/public/media/images/method.jpeg?itok=WoBy0av-)
How Has SCTLD Spread?
In addition to the identity of the causative agent(s), other unknowns surrounding SCTLD include how the disease has managed to spread so rapidly and so sporadically. In the Caribbean, for example, SCTLD outbreaks often popped up in seemingly random locations, suggesting the disease was not spreading via movement of natural water currents. Instead, these outbreaks often occurred near major ports, suggesting that ships may serve as vectors for the disease. However, the mechanisms by which this may occur remain unclear. One possibility is that SCTLD pathogen(s) may enter new areas attached to ships as biofilms (complex communities of microorganisms that form on submerged surfaces). Our work with Project MERMAID. revealed that biofilms formed on stainless steel in association with SCTLD-infected corals carried microbial signatures of the disease.
Coral Microbial Ecology
Measuring Coral Growth to Help Restore Reefs
Coral Disease
Prokaryotic Communities Shed by Diseased and Healthy Coral (Diploria labyrinthiformis, Pseudodiploria strigosa, Montastraea cavernosa, Colpophyllia natans, and Orbicella faveolata) into Filtered Seawater Mesocosms - Raw and Processed Data
The files in this data release are those referenced in the journal article by Evans and others (2023) entitled 'Investigating microbial size classes associated with the transmission of stony coral tissue loss disease (SCTLD)'. The files contain an amplicon sequence variant (ASV) table and the raw 16S rRNA gene amplicon files from fifty-six 0.22-micrometer (µm) pore size filters, as well as six rea
Prokaryotic Communities From Marine Biofilms Formed on Stainless Steel Plates in Coral Mesocosms - Raw and Processed Data
The files in this data release are those referenced in the journal article by Evans and others (2022) entitled "Ship Biofilms as Potential Reservoirs of Stony Coral Tissue Loss Disease." They contain an amplicon sequence variant (ASV) table and the raw 16S ribosomal ribonucleic acid (rRNA) gene amplicon deoxyribonucleic acid (DNA) sequence files from 15 microbial communities (sample names: CnD16B,
Bacterial Communities Shed by Montastraea cavernosa Coral Fragments into Filtered Seawater Mesocosms-Raw Data
Investigating microbial size classes associated with the transmission of stony coral tissue loss disease (SCTLD)
Effective treatment and prevention of any disease necessitates knowledge of the causative agent, yet the causative agents of most coral diseases remain unknown, in part due to the difficulty of distinguishing the pathogenic microbe(s) among the complex microbial backdrop of coral hosts. Stony coral tissue loss disease (SCTLD) is a particularly destructive disease of unknown etiology, capable of tr
Rapid prototyping for quantifying belief weights of competing hypotheses about emergent diseases
A meta-analysis of the stony coral tissue loss disease microbiome finds key bacteria in unaffected and lesion tissue in diseased colonies
Stony coral tissue loss disease (SCTLD) has been causing significant whole colony mortality on reefs in Florida and the Caribbean. The cause of SCTLD remains unknown, with the limited concurrence of SCTLD-associated bacteria among studies. We conducted a meta-analysis of 16S ribosomal RNA gene datasets generated by 16 field and laboratory SCTLD studies to find consistent bacteria associated with S
Biofilms as potential reservoirs of stony coral tissue loss disease
Since 2014, corals throughout Florida’s Coral Reef have been plagued by an epizootic of unknown etiology, colloquially termed stony coral tissue loss disease (SCTLD). Although in Florida the movement of this waterborne coral disease has been consistent with natural transport via water currents, outbreaks in the Caribbean have been more sporadic, with infections occurring in locations inconsistent