Coral Reefs Could Adapt to Rising Ocean Temperatures
“Fortune is not satisfied with inflicting one calamity” - Publilius Syrus - a Roman slave from the 1st century
BCE
On Thursday evening, in my capacity as a reporter for the Island Sand Paper, I had the privilege of attending a lecture given by coral reef scientist Dr. Andrew C. Baker. Dr. Baker holds a PhD in Marine Biology and is currently an assistant professor at the University of Miami. He was recently awarded the 2008 Pew Fellowship in Marine Conservation for his work in helping to protect corals against climate change. During his lecture Thursday at the NCH Healthcare System in Naples, Dr. Baker shared his latest research exploring innovative new ways to help corals adapt to increases in temperature and carbon dioxide in the world’s oceans. Dr. Baker’s friendly manner and ease of delivery made the fascinating subject matter easy to understand and the packed audience at the Garden of Hope and Courage all learned a great deal about corals and how Baker’s breakthrough research just may save them.
Dr. Baker began by showing charts illustrating how the carbon dioxide in the atmosphere has been steadily rising and is predicted to continue to do so. The carbon dioxide acts like a blanket and warms the oceans, too, with some predictions having the seas becoming 2 – 7 degrees Fahrenheit warmer by the end of the century. Dr. Baker explained that the reason that it’s happening doesn’t matter – the important thing is that it is happening.
“Corals are simple animals that thrive within a narrow temperature range,” said Dr. Baker, explaining a little bit about the life cycle of corals. “They depend on partnerships with microscopic algae to help them thrive in shallow tropical seas. These symbiotic algae live inside the corals and provide them with energy from photosynthesis, allowing corals to build their slow-growing limestone skeletons. In turn, the corals protect the algae by allowing them to live inside their bodies, preventing them from being consumed.” He described the mutual benefit being as if we humans were to cover ourselves with solar panels. The algae are also responsible for the bright colors that the corals exhibit.
One of the drawbacks to this relationship, however, is coral bleaching. Bleaching occurs when temperatures rise, causing the algae to get heat stress and produce oxygen radicals which are harmful to the coral. The coral than spit the algae out, resulting in the loss of their color - the coral actually turn white. The coral cannot survive without the algae, however, and usually die within a few weeks.
“In 1997-1998, an El Nino event caused a huge pool of warm water to sit in the East Indian Ocean. 95 % of the coral died from bleaching.”
Another problem with climate change that is negatively impacting coral is the acidity of our oceans. “As we pump carbon dioxide into the atmosphere, some dissolves into the ocean, with the result being that the ocean gets more acidic,” said Dr. Baker. “In fact, thirty percent of the total global carbon dioxide emissions since the year 1800 -118 billion metric tons- have been absorbed by the ocean through a slow chemical exchange between the atmosphere and sea surface,” he told the crowd. “As we acidify the oceans, it makes it more difficult for corals to build their skeletons, and by centuries’ end, corals will be growing only about half as fast,” he explained. “This is a real double whammy for corals.”
Dr. Baker then presented a chart showing that, by the year 2100, climate change will have rearranged our ecosystems to the point where species will be living in odd combinations- known as ‘no analog’ communities to scientists - nothing like them exists in the present world. “These combinations will not have occurred for 50 million years and we have no idea what is going to happen,” said Dr. Baker.
Now the doctor turned to what he called ‘a pessimistic’ climate model – one that showed a temperature threshold in the graph that, in relation to corals, is a horizontal line. “Looking at this chart, it appears that coral will be hit with bleaching events - on a par with the 1998 El Nino – every year and that by 2050, we will have lost the world’s coral reefs.” Dr. Baker told the now-horrified audience that he disagrees with that, and explained that finding a way to save the corals is what his research has been centered on.
“What if that line was able to go up – I mean, what if corals could adapt to the changes in temperature?” he said. Dr. Baker has spent much of his career looking at climate change impacts on corals and believes he has a solution. Along with fellow scientist Dr. Chris Langdon, he has created a lab at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science that allows them to test the vigor of coral reefs under environmental stress - in the first-ever simulated climate change laboratory for corals. This research project earned him the Pew Fellowship.
“The idea is based on the fact that all of these symbiotic algae are not the same species. In fact, their DNA is so different that, from a scientific viewpoint, there is more diversity than exists in mammals. The corals ‘decide’ which algae to host depending on their environmental conditions. As you move deeper on the reef, the same corals will have totally different algae as their symbiotic partners. Even one big individual coral head will have ‘sun-loving’ algae present in the coral animals on the top, and shade tolerant algae present towards the bottom.”
The big question, says Dr. Baker, is – ‘Is there a heat tolerant algae?’
Dr. Baker has traveled all over the world and collected 12,000 samples of coral, including species from the Persian Gulf, where, in waters warmer than the temperatures that normally cause bleaching, exist 50 species of coral. These coral are dominated by heat tolerant algae. He also looked at a bleaching event that occurred on the Panama Reef where some corals were able to survive by actually switching to more heat-tolerant algae. His paper that detailed this initial breakthrough discovery – that corals may be able to withstand climate change by switching algal partners – was published in the journal Nature and was subsequently hailed by Discover magazine as one of the “Top 100 Science Stories of 2001”. Having discovered this, his research now focuses on the bigger question – ‘Can we get coral to accept these heat-tolerant algae before a bleaching event occurs?’
“Unfortunately, these highly heat-tolerant algae aren’t all that common,” said Dr. Baker. “I’m wondering if we can’t culture more of them in the lab and introduce them to the coral and, if we do, will they switch.” Dr. Baker says he’s not proposing we go out to the world’s reefs with “teams of syringe-bearing divers” but rather either partner with reef restoration attempts already in progress or “go out during a bleaching event and choose the biggest and oldest coral colonies, which produce most of the structure and reproductive output of the reefs. If we can save the ‘big mamas’ it all seems worthwhile.”
In his lab, Dr. Baker plans to find out whether by raising baby coral under different temperatures and introducing the heat-tolerant algae will change the coral’s tolerance for warmer water. He also plans to see if existing coral pieces will switch to the more heat-resistant algae on a regular basis if the algae are available and the water warms enough.
He cautions, however, against getting too optimistic about his research. “Just because we might be able to get them to adapt doesn’t mean that the problem is solved,” he told the group. “If a virus was unleashed on the planet, and people discovered that they could survive it by running a 102 degree temperature, that doesn’t make for a healthy planet.”
There are other, seemingly ‘easier to fix’ problems that threaten corals’ existence almost as much as bleaching, Dr. Baker said. “For coral to have the best chance at survival means that we all need to be doing the best we can by trying to minimize all the other things that we’re constantly hitting them with.”
Those things include over-fishing, nutrient pollution and habitat destruction – where they actually dynamite the reef to kill fish. “By removing too many fish species, we increase the amount of seaweed on the reef,” he explained. “All of us are very comfortable about the idea of not shooting bears in Yellowstone National Park, but we go to an underwater national park and say, “What a great place to fish!”. We can cut greenhouse gasses all we want, but people’s attitudes have still got to change.”
Dr. Baker talked about our reef system here in Florida, which stretches from the Dry Tortugas, roughly sixty-seven miles west of Key West, all the way to the Palm Beaches. “The coral reefs of the Florida Keys are the only true coral reefs in the continental waters of the United States,” he said, “And the dominant coral species used to be Elkhorn and Staghorn coral. Those species have gone down 97% without a single bleaching event.”
This reporter recalls diving in places like Bonaire and Belize, and seeing Elkhorn and Staghorn coral so thick it was impossible to swim through – something I have never witnessed in the Florida Keys. “They’re also the fastest growing corals on the reef – with an average growth rate of 10-20cm a year for Staghorn and 5-10cm a year for Elkhorn,” Dr. Baker told us.
Dr. Baker said that the dire situation was finally officially recognized when both coral species were listed on the Endangered Species List in October of 2006, ensuring that they’ll receive better protection. Now, before any activity can begin, the possible negative impact on the coral must be assessed. He went on to say that NOAH has identified a 5,000 square mile area that includes the Florida Keys, Puerto Rico and the Virgin Islands as a critical habitat for corals.
“The bad thing is there had to be a lawsuit – brought by the Center For Biological Diversity - in order to get the coral listed,” Dr. Baker said, beginning to wrap up his presentation. “The current administration has listed fewer species total than any other previous administration did in one year, and they have all only been added as the result of lawsuits.”
With that, Dr. Baker opened the lecture up to questions from the audience. The questions ranged from concerns about the possibility of genetically engineering the structure of the corals to be more resistant to climate change – “No one has tried, plus it would bring up a host of environmental concerns” - to the possibility of the reefs completely relocating to warmer regions – “That is a possibility but it would take hundreds of years and be limited to certain areas with hard sea bottoms,” he responded.
Dr. Baker encouraged everyone to become more informed and to educate others, especially lawmakers, about the concerns corals face.
“Coral reefs are vital to a flourishing economy,” he said, pointing out that reefs contribute some 300 billion dollars to the worldwide economy each year, with four billion dollars a year in Florida alone. “They are crucial in establishing fisheries, and act as buffers against the effects of powerful storms and hurricanes. Their loss would mean tremendous economic hardships worldwide.”
Keri Hendry - published in the Island Sand Paper April 11, 2008
