by Michael Marshall
Three bacteria seem to be responsible for a disease that has killed most of the Caribbean's reef-building corals.
White band disease causes the outer layer of corals to turn white and peel off. First noticed in the 1970s, it has swept through the Caribbean's staghornand elkhorn corals. Both are now critically endangered. They are the region's only branched corals, creating most of the complex habitat that animals like fish rely on, so their loss has depleted the entire ecosystem.
"This disease has taken out the key ecosystem architects," says David Smith of the University of Essex in Colchester, UK.
Now some likely culprits for white band disease have been identified. Michael Sweet of the University of Derby in the UK and colleagues treated diseased corals with antibiotics and tracked whether they recovered. They also monitored changes in the microorganisms present. If an antibiotic killed a microbe, but the coral did not recover, that microbe was not responsible for the disease.
Three suspectsThree bacteria were consistently present in diseased corals, but not healthy ones: Vibrio charchariae – a long-suspected offender – Lactobacillus suebicus and an unidentified species of Bacillus. One or more seems to be responsible for white band disease.
Other bacteria have been tentatively identified in earlier studies, and Smith says they might also trigger the disease. "The likelihood is that at different times, different bacteria cause an infection," he says.
The team also found that the tissue damage that gives the disease its name is caused by a single-celled organism called a ciliate. Killing the ciliate did not stop the disease, but it reduced the tissue damage, suggesting the ciliate was taking advantage of the bacterial infection.
Both the bacteria and the ciliate seem to be essential to create white band disease. "You wouldn't get a disease without the bacteria," says Sweet. "But without the ciliate, you get a different disease."
Smoking gunCould the discovery help save the staghorn and elkhorn corals? Possibly. "Getting this smoking gun really provides you with conservation options," says Smith. It might be possible to identify where the bacteria are coming from and target the site – human activity, such as sewage dumping, may have boosted the bacteria, for example.
Tempting as it might be, we can't treat white band disease with antibiotics, at least not in the wild, says Smith. For one thing, there is already a global epidemic of antibiotic-resistant bacteria, and spraying reefs with antibiotics would only make it worse. Also, corals are home to "good" bacteria and cannot survive without them. "Antibiotics could knock out the bacteria that are required by the coral," says Smith.
However, Sweet wants to try boosting the coral's good bacteria, which help it fight off infections. "We could dose it with the coral's natural microflora," he says, and see if that boosts the coral's immune response. He calls this approach "Yakult for coral".
By CB Online Staff firstname.lastname@example.org; email@example.com
International insurer Catlin Group Limited is underwriting a massive expansion of its study of coral reefs with a new campaign in the Caribbean and Bermuda. The Catlin Seaview Survey program – which will significantly widen opportunities for ocean, coral and climate scientists to understand the changes that are occurring within the region – starts in Belize, Mexico, Bermuda, St. Vincent, Guadeloupe, Turks and Caicos and the Bahamas.
Coral reefs in the Caribbean, like elsewhere, are under growing environmental stress. Being highly sensitive to environmental change, corals are considered the “canary in the coal mine” when it comes to impacts of climate change and ocean acidification. Exploitation, pollution, warming waters and increased storms linked with climate change has caused the massive loss of corals across the Caribbean Sea over the last 50 years.
Caribbean economies given their dependence on coral reefs and other marine ecosystems for goods, services and economic welfare. According to the World Resources Institute, the value of shoreline protection services provided by Caribbean reefs is between $700 million and $2.2 billion per year. Within the next 50 years, continuing coral degradation and death could lead to losses totaling $140 million to $420 million annually.
“We are committed to understanding the future risks posed by climate change,” said Catlin Group CEO Stephen Catlin. “It is not only important that scientists have access to this valuable data, but companies such as ours must understand the impact that significant changes to our environment will have on local economies.”
A scientific race against time
Coral reefs globally are in an unprecedented state of decline due to pollution, overfishing and climate change. The U.S. National Oceanic &d Atmospheric Administration (NOAA) predict increasing frequency and severity of mass bleaching events over the coming years. As the Catlin Seaview Survey embarks on a race against time to survey the coral reefs of the world, the Caribbean serves as an ideal launching point to take the campaign global because of the stress already experienced by its reefs.
“The Caribbean was chosen to launch the global mission because it is at the frontline of risk. Over the last 50 years, 80 percent of the corals in many places in the Caribbean have disappeared because of coastal development and pollution. They now are also threatened by invasive species, climate change and ocean acidification – it’s the perfect storm,” said Richard Vevers, project director for the Catlin Seaview Survey.
Coral reefs pump some $483 million annually into the U.S. economy tied to tourism and water sports, according to a study. NOAA says reef-based U.S. fisheries represent another $100 million in commercial activity every year.
An international conservation organization painted a grim picture of the Caribbean’s iconic coral reefs in a recent report.
The International Union for Conservation of Nature said in September that the Caribbean’s reefs are in sharp decline. The report pointed to Puerto Rico and the U.S. Virgin Islands among the hardest-hit in the region.
The causes include overfishing, pollution, disease and bleaching caused by rising global temperatures.
Scientists say record amounts of coral have died off in the Caribbean from pollution, sedimentation and rising sea temperatures since the late 1990s and reefs in Puerto Rico are still under stress from an unprecedented bleaching event and die off that began in 2005. Puerto Rico’s reefs have shown some signs of recovering from the catastrophic bleaching event of 2005, which took a huge toll on vital coral populations.
When corals are exposed to very warm water, they either expel or consume the colorful algae they host, which leads to the bleached color. If the stress is not too severe and decreases in time, the affected corals can regain their symbiotic algae. But if the stress is prolonged and the algae populations do not recover, the coral host eventually dies.
In 2005, up to 90 percent of corals in parts of the eastern Caribbean suffered bleaching, and more than half died, according to previous research.
Tourism-dependent islands worry about the effect that bleaching will have on their economies. A rapid decline in the world’s coral reefs could damage economies that rely on underwater sea life for tourism revenue, researchers say. After the 2005 bleaching, the World Resources Institute estimated Caribbean reef degradation would cause between $350 million to $870 million in economic losses a year, according to a 2006 NOAA statement.
Pollution, habitat destruction, improper fishing and overfishing have contributed to the problem and corals in the eastern Caribbean have been hit hardest.
Survey focused on four main scientific goals
It is expected the state of the Caribbean reefs will provide insights into the future prospects for coral reefs in other regions of the world. Specifically, the new survey will focus on four major scientific goals:
– Change detection (creating a Caribbean-wide ecological baseline): Accurate measurements of the current state of the coral reefs in the Caribbean are crucial to support timely decisions about their management.
– Understand stress within the Caribbean – when, where and how much?: The survey team will use direct measurements as well as information from NOAA and NASA satellite systems to understand how patterns in the health of coral reefs (e.g. coral cover, reef complexity) are influenced by local and global stressors such as changes in sea temperature, coastal pollution, fishing intensity, and exposure to wave stress and storms. This will fill in critical gaps in our understanding of why coral reefs have been in decline over the past 50 years.
– Understanding climate change vulnerability: Develop deeper insights into mesophotic (deep-water) coral reef communities: The Catlin Seaview Survey’s work during 2012 on the Great Barrier Reef has revealed that mesophotic coral reefs may play an essential role in regenerating shallow water reef systems. The Survey will gather a more comprehensive understanding of the threat of climate change to coral reefs in the Caribbean by using similar techniques and technologies to map mesophotic coral reefs in the region and to investigate the genetic connectedness of those reefs to shallow water reef systems.
– Produce new tools for understanding changes in tropical reef systems: Rapid, semi-automated and rigorous surveys of coral reefs are essential for developing an understanding of the rates of change, vulnerability and priorities for management intervention. To aid in the Survey’s campaign, a new camera has been developed; the SVII-S is a lighter-weight version of the main SVII camera that can be operated by a single diver, allowing dive team members to cover extra survey areas
Climate change and implications for the insurance industry
500 million people worldwide rely on coral reefs for food, tourism, economic stability and shoreline protection. When reefs are harmed or destroyed due to climate change and regional drivers, the effects can be devastating and far-reaching. There is a shift in the insurance industry; evaluating and helping clients minimize risk is critical to business, the assessment of the impact of climate change is a natural extension for the future of the insurance industry.
The Geneva Association, the international association for the study of insurance economics, recently released a report, Warming of the Oceans and Implications for the (Re) Insurance Industry, highlighting how climate change has effected the warming of oceans and the correlating effect on the insurance industry’s risk assessment strategies. The report highlights three main drivers of change:
– Greater volumes of water = greater risk: Not only do rising sea levels increase the risk of flooding or the potential impact of storm surges, but they also decrease the protective lifespan of coastal infrastructure. While the probability of a storm is not increased, the damage caused by one is.
– Warmer ocean = more water in the atmosphere: A warmer atmosphere contains more water and therefore more energy. This has the potential to increase the intensity of extreme events and associated precipitation. This greater intensity increases the loss potential of natural catastrophes.
– Effect on large-scale climate patterns: The warming of the oceans is also likely to affect large-scale climate patterns such as El Niño, various monsoon systems or the North Atlantic Oscillation.
The Catlin Seaview Survey has teamed up with the Global Change Institute at The University of Queensland in Australia and Davey Kline, a project scientist at Scripps Institution of Oceanography at the University of California-San Diego. Kline and other Scripps collaborators are working with the Global Change Institute to develop autonomous assessments of the hundreds of thousands panoramic images taken of the reefs within the Caribbean using their sophisticated semi-automated image recognition software to analyse the percent coverage of the main benthic organisms (e.g. corals, algae, other invertebrates) in the photographs. Analysis of such a large data set of photographs would not be possible without a semi-automated computer analysis system.
These relationships are essential to the success of the research program,” said professor Ove Hoegh-Guldberg, chief scientist of the Catlin Seaview Survey. “By collecting and analyzing images in a semi-autonomous fashion, the research project can cover huge distances. This has never been done before.”
Catlin Group Limited is a global specialty property/casualty insurer and reinsurer operating worldwide through six underwriting hubs: London/UK, Bermuda, the United States, Asia Pacific, Europe and Canada.
Coral reef in Florida. (Credit: Florida Keys National Marine Sanctuary staff)
To prevent coral reefs around the world from dying off, deep cuts in carbon dioxide emissions are required, says a new study from Carnegie's Katharine Ricke and Ken Caldeira. They find that all existing coral reefs will be engulfed in inhospitable ocean chemistry conditions by the end of the century if civilization continues along its current emissions trajectory.
Coral reefs are havens for marine biodiversity and underpin the economies of many coastal communities. But they are very sensitive to changes in ocean chemistry resulting from greenhouse gas emissions, as well as to coastal pollution, warming waters, overdevelopment, and overfishing.
Ricke and Caldeira, along with colleagues from Institut Pierre Simon Laplace and Stanford University, focused on the acidification of open ocean water surrounding coral reefs and how it affects a reef's ability to survive.
Coral reefs use a mineral called aragonite to make their skeletons. It is a naturally occurring form of calcium carbonate, CaCO3. When carbon dioxide, CO2, from the atmosphere is absorbed by the ocean, it forms carbonic acid (the same thing that makes soda fizz), making the ocean more acidic and decreasing the ocean's pH. This increase in acidity makes it more difficult for many marine organisms to grow their shells and skeletons, and threatens coral reefs the world over.
Using results from simulations conducted using an ensemble of sophisticated models, Ricke, Caldeira, and their co-authors calculated ocean chemical conditions that would occur under different future scenarios and determined whether these chemical conditions could sustain coral reef growth.
Ricke said: "Our results show that if we continue on our current emissions path, by the end of the century there will be no water left in the ocean with the chemical properties that have supported coral reef growth in the past. We can't say with 100% certainty that all shallow-water coral reefs will die, but it is a pretty good bet."
Deep cuts in emissions are necessary in order to save even a fraction of existing reefs, according to the team's results. Chemical conditions that can support coral reef growth can be sustained only with very aggressive cuts in carbon dioxide emissions.
"To save coral reefs, we need to transform our energy system into one that does not use the atmosphere and oceans as waste dumps for carbon dioxide pollution. The decisions we make in the next years and decades are likely to determine whether or not coral reefs survive the rest of this century," Caldeira said.
By: Bernd F. Laeschke
Southampton (global-adventures.us): Increased levels of nutrients in the water column can increase the susceptibility of corals to fall victim to bleaching, research conducted at University of Southampton’s Coral Reef Laboratory shows. Corals are marine animals that have a mutually beneficial, or ‘symbiotic’, relationship with algae that live in their tissue. Studies have shown that when water temperatures rise beyond a certain threshold, the corals expel the algae, which can increase mortality of the host and turns the corals white.
“The increasing influx of nutrients in coastal waters due to human activities represents a pressing problem for coral reefs,” says Dr. Joerg Wiedenmann, head of the Coral Reef Laboratory. “A better understanding of the links between disturbed nutrient levels and coral bleaching is vital to develop marine and coastal management strategies, whichhelp to ensure future health of coral reefs.”
Wiedenmann’s project ‘Incorals’ has been recognized by the European Research Council’s Starting Grant competition by granting a 1.29 million Euros award. The project will build on the initial findings and investigate the detailed mechanisms that underlie the responses of corals and their symbiotic algae to nutrient stress.
The ‘Starting Grant’ scheme is a program aimed at early-career researchers, supporting a new generation of top scientists in Europe. Funding is provided to set up research teams and to develop the best ideas at the frontiers of knowledge. The 2012 competition attracted 4,741 applications competing for a share of the 800 million euro budget.
A YouTube video explaining the research undertaken at the universities coral reef lab facility is available here. Current science suggests that coral bleaching is promoted by global warming, eventually threatening to wipe out coral reefs around the world.
Coral colonies are symbiotic marine animals susceptible to rising water temperatures and increased nutrient levels. Approximately 10 percent of the world’s coral reefs are dead, and 60 percent are at risks due to human activity. Some dead corals are washed up on beaches around the world.
The Caribbean’s coral reefs have collapsed, mostly due to overfishing and climate change, according to a new report released by the International Union for Conservation of Nature (IUCN).
In the most comprehensive study yet of Caribbean coral reefs, scientists have discovered that the 50 to 60 percent coral cover present in the 1970s has plummeted to less than 10 percent.
“I’m sad to tell you it’s a dire picture,” Carl Gustaf Lundin, director of IUCN’s Global Marine and Polar Programme, said at a news briefing Friday at the World Conservation Congress in Jeju Island, South Korea.
Called “Nature’s Olympics,” the conference will explore five environmental themes over five days. Today’s theme is Nature+ Climate, which focuses on how to combat global warming.
Much of the decline is caused by a massive die-off of sea urchins in the 1970s—possibly due to disease. Without these reef grazers—the “cows in the field” that keep vegetation in check—the number of algae and grasses have skyrocketed, dominating reefs and pushing corals aside, Lundin said.
What’s more, overfishing of grazer species such as parrotfish or surgeonfish is allowing more algae to take over and outcompete the coral, said Ameer Abdulla, IUCN senior advisor on Marine Biodiversity and Conservation Science.
“Coral reef communities are just like human communities—there are different roles that are fundamental to keeping the system going,” Abdulla said.
For example, if all the engineers were taken out of a human society, that would affect how the society functions.
The same phenomenon is happening with the loss of the Caribbean’s grazers, he said.
Global Warming Also at Play
The scientists also said that warmer water—often caused by hurricanes blowing through—have harmed reefs. When the water gets too hot, algae that live inside coral, called zooxanthellae—abandon their hosts, causing the coral themselves to bleach and eventually die.
Though some reefs can bounce back from such periods of warmer water, notably in the Indian Ocean, ”We have heating happening with much higher frequency and for longer duration,” Lundin told National Geographic News.
For instance, some 500-to-a-thousand-year-old corals in the Indian Ocean have died due to warmer water.
“We know with some certainty we haven’t had this happen for a thousand years, that’s a clear indication that something’s afoot,” Lundin said.
“For those that are very skeptical of what’s happening with climate change, I would say reality is not in their favor.”
Caribbean Collapse a First—Others May Follow
Corals are vital for many reasons, from boosting tourism dollars to local communities and even buffeting islands themselves from powerful storm surges, Lundin said.
The good news is that there are ways to protect the remaining 10 percent of Caribbean corals.
“The urgency of improving management is certainly there—our message is we need to encourage the people who are the custodians of the resources to take charge. We do know a lot about what one can do,” said Lundin.
For instance, putting in place marine protected areas can reduce the pressure of overfishing. Governments can also work with local fishers to maintain their livelihoods, for instance by raising the value of individual fish so that the fishers catch fewer animals.
The bottom line, Abdulla said, is that “the Caribbean system is one of first systems to experience collapse—it’s something that will happen across the globe if human use of coral reefs continues as it is.”
Christine Dell’Amore, environment writer-editor for National Geographic News, is reporting from the IUCN World Conservation Congress in Jeju Island, South Korea.