Coral Reef and Tropical Fish (Shutterstock www.shutterstock.com)
2023/04/07
MIAMI — On a coral reef, white is the color of death.
So when researchers see a flash of bone white amid the riot of colorful corals, fish and sea creatures, they know something is wrong. If it’s all white, the coral likely bleached to death in the steamy hot seas. But if it’s a patch of white surrounded by the raggedy brown edges of living coral tissue, they know the most devastating coral disease in the Caribbean has likely struck.
Stony coral tissue loss disease is a new and deadly disease affecting reefs throughout the Caribbean. Unlike other coral diseases, it affects more than 20 species, and it kills fast — sometimes within a matter of days.
But after nearly a decade of devastating losses, scientists finally have some good news. They have found at least one way to fight back, and they’re already testing it on Florida’s reefs.
A new paper published in the journal Communications Biology found that applying probiotic bacteria — yes, similar to the kind in your yogurt — to corals could prevent the disease, or even reverse some of its symptoms.
“We think about probiotics for our food, but this is probiotics for the reef,” said Julie Meyer, an assistant professor at the University of Florida’s department of soil, water and ecosystem sciences and one of the authors of the study, published Thursday.
One healthy coral leads to more
Scientists first discovered the beneficial bacteria a few years back during an experiment where researchers tried to infect healthy corals with the disease to understand how it spread. But one coral just wouldn’t get sick.
Bacteria cultured off of that one coral eventually turned into whole tanks of bacteria, which scientists turned into a paste and started smearing on sick corals. It worked.
Next up were field trials in corals off the coast of Fort Lauderdale and Marathon, in the Keys. Scientists used two methods, sticking the paste on individual corals or dropping a big weighted bag over the colony, pumping in liquid bacterial cultures, and letting the whole thing marinate for a few hours.
Both methods worked, Meyer said, just not as well as they did in the lab.
“In the lab, it’s very effective. In the environment, it’s harder to say because there’s so many variables going on,” she said.
However, scaling up this solution may prove difficult. Florida has hundreds of miles of reef tract, spotted with tens of thousands of sick corals. Tending to each one with a tub of paste, or even the weighted bag, is slow work.
“It’s manpower limitation. It’s a lot of work to go out there and hand-apply this stuff,” she said.
Still, Meyer said her research team is excited at the possibilities shown in this research. For nearly a decade, researchers have been throwing everything they could at these corals — even, she said, essential oils.
So far, the most promising advance has come from antibiotics. Scientists have been successfully using amoxicillin (the same stuff humans get for bacterial infections) to treat sick corals for a few years.
But scientists are worried that using too many antibiotics could create an antibiotic-resistant strain of the disease, and they’re trying to move away from using medicines that humans rely on.
“We don’t want to build that resistance when we need to use it ourselves,” Meyer said.
Born in Miami
While much about the disease is still a mystery, scientists are sure of a few things.
They know it was first spotted off Virginia Key in 2014 and quickly raced around the Caribbean. It was devastating. Research from Nova Southeastern University found that at least four species of coral in Florida lost 98% or more of their living tissue to the disease.
Die-off from this disease peaked in Florida around 2016, but it’s still on the move.
In 2021, stony coral tissue loss disease reached the final untouched pocket of Florida: the Dry Tortugas in the Keys. And just this week, scientists recorded a sighting of a sick coral all the way across the Caribbean, in Curacao.
While research hasn’t fingered a specific culprit for the spread of the disease, one of the leading theories is contaminated ballast water from cruise and cargo ships. Miami is the busiest cruise port in the world, and the spread of the disease throughout the Caribbean reflects popular cruising routes.
“When it arrives in a new location it’s around the port areas, and it doesn’t follow ocean currents or anything,” Meyer said.
But so far, no government has asked cruise or cargo ships to alter their behavior to potentially slow the spread of the disease.
And while this new research represents some success in the fight against the spread of stony coral tissue loss disease, researchers said that saving Florida’s beleaguered coral reefs requires hitting all of the problems they’re facing at once, like coral bleaching, ocean acidification and wastewater spills, which are all worsened by climate change.
That’s because each of those factors makes coral weaker and more stressed out, Meyer said, and more susceptible to disease.
“In general, we kind of have to diminish all the stresses on corals in Florida,” she said.
© Miami Herald
Newly discovered probiotic could protect Caribbean corals threatened by deadly, devastating disease
New treatment offers an alternative to antibiotic treatment, reducing risk of resistant pathogenic bacteria
Peer-Reviewed PublicationIMAGE: A CLOSE-UP OF EXTENDED POLYPS OF AN APPARENTLY HEALTHY GREAT STAR CORAL COLONY (MONTASTRAEA CAVERNOSA) ON A REEF NEAR FORT LAUDERDALE, FLORIDA. THE TENTACLES SURROUNDING THE MOUTH OF EACH POLYP HELP TRAP FOOD PARTICLES FOR THE CORAL TO EAT. THE BROWN COLORATION IS FROM THE SYMBIOTIC MICROALGAE (SYMBIODINIACEAE) THAT LIVE IN THE CORAL TISSUES. RESEARCHERS WITH THE SMITHSONIAN’S NATIONAL MUSEUM OF NATURAL HISTORY HAVE DISCOVERED THE FIRST EFFECTIVE BACTERIAL PROBIOTIC FOR TREATING AND PREVENTING STONY CORAL TISSUE LOSS DISEASE (SCTLD), A MYSTERIOUS AILMENT THAT HAS DEVASTATED FLORIDA’S CORAL REEFS SINCE 2014 AND IS RAPIDLY SPREADING THROUGHOUT THE CARIBBEAN. THE PROBIOTIC TREATMENT, DESCRIBED IN A PAPER PUBLISHED TODAY IN COMMUNICATIONS BIOLOGY, PROVIDES AN ALTERNATIVE TO THE USE OF THE BROAD-SPECTRUM ANTIBIOTIC AMOXICILLIN, WHICH HAS SO FAR BEEN THE ONLY PROVEN TREATMENT FOR THE DISEASE BUT WHICH RUNS THE RISK OF PROMOTING ANTIBIOTIC-RESISTANT BACTERIA. view more
CREDIT: VALERIE PAUL
Researchers with the Smithsonian’s National Museum of Natural History have discovered the first effective bacterial probiotic for treating and preventing stony coral tissue loss disease (SCTLD), a mysterious ailment that has devastated Florida’s coral reefs since 2014 and is rapidly spreading throughout the Caribbean.
The probiotic treatment, described in a paper published today in Communications Biology, provides an alternative to the use of the broad-spectrum antibiotic amoxicillin, which has so far been the only proven treatment for the disease but which runs the risk of promoting antibiotic-resistant bacteria.
SCTLD afflicts at least two dozen species of so-called hard corals, which provide essential habitat for innumerable fishes and marine animals of economic and intrinsic value while also helping to defend coastlines from storm damage. Since its discovery in Florida in 2014, cases of SCTLD have been confirmed in at least 20 countries. The precise cause of the malady remains unknown but once a coral is infected, its colony of polyps can die within weeks.
“It just eats the coral tissue away,” said Valerie Paul, head scientist at the Smithsonian Marine Station at Fort Pierce, Florida, and senior author of the study. “The living tissue sloughs off and what is left behind is just a white calcium carbonate skeleton.”
Paul has been studying coral reefs for decades, but she said she decided to go “all in” on SCTLD in 2017 because it was so deadly, so poorly understood and spreading so fast.
While probing how the disease is spread, Paul and a team including researchers from the University of Florida discovered that some fragments of great star coral (Montastraea cavernosa) swiftly developed SCTLD’s characteristic lesions and died, but other pieces never got sick at all.
Though the precise cause of SCTLD is unknown, the efficacy of antibiotics as a treatment suggested pathogenic bacteria were somehow involved in the progression of the disease.
For this reason, the researchers collected samples of the naturally occurring, non-pathogenic bacteria present on a pair of disease-resistant great star coral fragments for further testing. With these samples, the research team aimed to identify what, if any, naturally occurring microorganisms were protecting some great star corals from SCTLD.
First, the team tested the 222 bacterial strains from the disease-resistant corals for antibacterial properties using three strains of harmful bacteria previously isolated from corals infected with SCTLD. Paul and Blake Ushijima, lead author of the study and an assistant professor at the University of North Carolina Wilmington who was formerly a George Burch Fellow at Smithsonian Marine Station, found 83 strains with some antimicrobial activity, but one in particular, McH1-7, stood out.
The team then conducted chemical and genetic analyses to discover the compounds behind McH1-7’s antibiotic properties and the genes behind those compounds’ production. Finally, the researchers tested McH1-7 with live pieces of great star coral. These lab trials provided the final bit of decisive proof: McH1-7 stopped or slowed the progression of the disease in 68.2% of 22 infected coral fragments and even more notably prevented the sickness from spreading in all 12 transmission experiments, something antibiotics are unable to do.
Going forward, Paul said there is a need to work on improved delivery mechanisms if this probiotic is going to be used at scale in the field. Currently, the primary method of applying this coral probiotic is to essentially wrap the coral in a plastic bag to create a mini aquarium and then inject the helpful bacteria. Perhaps even more importantly, Paul said it remains to be seen whether the bacterial strain isolated from the great star coral will have the same curative and prophylactic effects for other species of coral.
The potential of this newly identified probiotic to help Florida’s embattled corals without the danger of inadvertently spawning antibiotic resistant bacteria represents some urgently needed good news, Paul said.
“Between ocean acidification, coral bleaching, pollution and disease there are a lot of ways to kill coral,” Paul said. “We need to do everything we can to help them so they don’t disappear.”
This interdisciplinary research is part of the museum’s new Ocean Science Center, which aims to consolidate museum’s marine research expertise and vast collections into a collaborative center to expand understanding of the world’s oceans and enhance their conservation.
This research was supported by funding from the Smithsonian, the Florida Department of Environmental Protection, the National Science Foundation, the National Oceanic and Atmospheric Administration and the National Institutes of Health.
The remaining live tissue on this great star coral colony (Montastraea cavernosa) in Florida is being destroyed by stony coral tissue loss disease (SCTLD). The bright white margin surrounding the dark brown, living coral tissue is where the coral is bleaching and dying due to the disease. SCTLD afflicts at least two dozen species of so-called hard corals, which provide essential habitat for innumerable fishes and marine animals of economic and intrinsic value while also helping to defend coastlines from storm damage. Since its discovery in Florida in 2014, cases of SCTLD have been confirmed in at least 20 countries. The precise cause of the malady remains unknown but once a coral is infected, its colony of polyps can die within weeks. Researchers with the Smithsonian’s National Museum of Natural History have discovered the first effective bacterial probiotic for treating and preventing SCTLD, a mysterious ailment that has devastated Florida’s coral reefs since 2014 and is rapidly spreading throughout the Caribbean.
A close look at a piece of diseased great star coral (Montastraea cavernosa) that is cut and ready for testing and treatment in an aquarium. The white coral skeleton on the left shows where two coral polyps have already died from stony coral tissue loss disease (SCLTD). Researchers with the Smithsonian’s National Museum of Natural History have discovered the first effective bacterial probiotic for treating and preventing SCTLD, a mysterious ailment that has devastated Florida’s coral reefs since 2014 and is rapidly spreading throughout the Caribbean. While probing how the disease is spread, the research team discovered that some fragments of great star coral swiftly developed SCTLD’s characteristic lesions and died, but other pieces never got sick at all. Though the precise cause of SCTLD is unknown, the efficacy of antibiotics as a treatment suggested pathogenic bacteria were somehow involved in the progression of the disease. For this reason, the researchers collected samples of the naturally occurring, non-pathogenic bacteria present on a pair of disease-resistant great star coral fragments for testing. With these samples, the research team aimed to identify what, if any, naturally occurring microorganisms were protecting some great star corals from SCTLD.
CREDIT
Kelly Pitts
JOURNAL
Communications Biology
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Chemical and genomic characterization of a potential probiotic treatment for stony coral tissue loss disease
ARTICLE PUBLICATION DATE
6-Apr-2023
Tools for coral gardening at the landscape scale
VIDEO: LEARN HOW KAUST MARINE SCIENTISTS ARE HELPING TO RESTORE CORAL REEFS. view more
CREDIT: © 2023 KAUST.
A toolkit for environmentally friendly and cost-effective coral restoration could accelerate the recovery of degraded reefs along the coast of Saudi Arabia and beyond.
Coral reefs support around 30 percent of marine wildlife and provide invaluable ecosystem services, such as fishing, tourism and coastal protection. But these vital habitats are rapidly disappearing.
Despite international climate agreements to reduce carbon emissions and limit global warming, scientists fear that coral reefs have passed a tipping point and will continue declining even under the most optimistic climate scenarios. “We have lost roughly one-third of global coral cover in the last 50 years,” says marine scientist Sebastian Schmidt-Roach, “and we urgently need active measures to mitigate further decline.”
Coral restoration could now be the best line of defense, but progress has been limited by the cost and labor intensity of working in marine environments. Current restoration and coral gardening, or “reefscaping,” projects tend to be small, covering just 500 square meters on average. “We need to target areas of thousands of square kilometers,” says evolutionary biologist Manuel Aranda. “One way to do this is through selective breeding of more resilient corals so that we do not have to restore every reef ourselves, but rather leave some resilient colonies to do the job for us.”
To help achieve industrial-scale coral restoration, the Coral Hub team, including Carlos Duarte and Charlotte Hauser, have created MaritechtureTM – a suite of tools for transporting selectively bred corals from the lab to the reef[1].
The patented system includes tiles that act as a substrate for growing corals: stackable crates to which the tiles can be attached, and MaritechtureTM Reef Nails that will not enable quick attachment of the tiles to natural reef substrates. For reef surfaces where nails won’t work, they created MaritechtureTM Coral Pods – freestanding limestone structures consisting of two plates that interlink to create a four-legged “pod” with a large surface area for attaching tiles or coral fragments.
The researchers calculate that a team of six divers could deploy 90 pods, creating up to 250 square meters of reefscape in half a day. The coral tiles are microchipped so researchers can see what works where and what does not. “Interestingly, our structures have already attracted a lot of natural coral settlement,” adds Schmidt-Roach, a promising sign that these artificial reefs could self-colonize.
Designed in collaboration with artist Julian Charrière, the objects are inspired by the 20th century German Bauhaus style of simple yet functional shapes and rational materials. “Their simple design enables flexibility and low-cost and easy application across different habitats, including in developing nations” says Schmidt-Roach.
“We have tried to minimize the use of plastics and metals. Limestone is a natural reef-like material with significantly less carbon emissions than conventional steel- or cement-based solutions,” Schmidt-Roach explains. Where necessary, the team uses acrylonitrile butadiene styrene, a nontoxic and recyclable plastic that does not degrade in water.
KAUST has announced that MaritechtureTM technologies will provide the backbone of their ambitious Reefscape Restoration Project at Shushah, which Schmidt-Roach’s team initially planned and won funding for. At 100 hectares, this is the world’s largest restoration project to date. MaritechtureTM will soon be commercialized by the team’s start-up Ocean Revive. “We are continually exploring new sustainable materials and nature-based solutions at the interface between science, art and technology,” adds Schmidt-Roach.
JOURNAL
Frontiers in Marine Science
ARTICLE TITLE
Novel infrastructure for coral gardening and reefscaping
Sebastian Schmidt-Roach (left) and Professor Manuel Aranda (right) inspect the health of their sample coralspecimens growing on their patented Maritechture structure.
The different components needed for building the Maritechture structure, including acrylonitrile butadiene styrene, a nontoxic and recyclable plastic that does not degrade in water.
CREDIT
© 2023 KAUST; Eliza Mkhitaryan.
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