Defenders of Wildlife Blog

©USFWS Pacific

Dr. Nathan Kirk 
Dr. Daniel Thornhill, Coral Reef Marine Scientist

Corals are remarkable animals that build massive and complex reef structures throughout the tropical oceans. For example, the structure of Australia’s Great Barrier Reef has grown so large that it is visible from outer space! Much of the success of corals, and therefore of coral reef ecosystems, results from tiny symbiotic algae, known as Symbiodinium or zooxanthellae, that live within the coral’s cells. These symbiotic algae act like tiny plants, giving the coral energy and promoting coral growth in exchange for nutrients and a safe place to call home.

Each coral has its own symbiotic micro-algae (©Todd C LaJeunesse)

Symbiodinium are not the only organisms that make their home within corals. In fact, coral colonies contain many species, like bacteria, fungi, flat worms, annelid worms, mussels and barnacles, to name just a few. These symbiotic organisms can hurt, help or just coexist with corals. In some cases these organisms can cause corals to sicken and die, so it is important to understand how these organisms affect corals in order to protect our imperiled reefs.

One enigmatic group of microorganisms sometimes found within corals is called apicomplexans. These microbes are closely related to the Symbiodinium that help power corals and build reefs. However, unlike their algal brethren, apicomplexans are almost always parasites. The species most familiar to us is malaria (Plasmodium falciparum), which causes severe illness in people throughout the world. Apicomplexans also include the human pathogens Toxoplasma and Cryptosporidium, both of which can cause severe sickness, especially in people with weakened immune systems. Though the effects of Apicomplexans on humans and other animals are well documented, what apicomplexans are doing to corals is still anyone’s guess.

In order to better understand how common apicomplexans are within corals, researchers at Auburn University, the University of Georgia, and Defenders of Wildlife examined four different coral species in the Florida Keys and the Bahamas over several years. To our surprise, we found that nearly all coral colonies, regardless of health, were associated with apicomplexans year-round.

Bleached coral (©Oregon State University)

So what does this mean for corals that are already under stress from pollution, overfishing, ocean acidification and global climate change? In an earlier study, Drs. Steve Upton and Esther Peters found apicomplexans in corals that were undergoing partial bleaching, which can be a sign of stress. But they also found apicomplexans in healthy-looking coral tissue. Our study found something similar: we detected apicomplexans seasonally within the same coral colonies, some of which are several hundred years old and none of which showed signs of disease.

With so much wildlife depending on coral reefs – thousands of species, from fish and sponges to anemones and sea turtles – we need to know if this organism could be a threat to corals as well. We will need to learn more before we’ll know whether or not they truly are parasites of corals, and if so, how to protect coral reefs from them. This research can help us understand the threats facing coral reef wildlife, and may even help us cope with our own apicomplexan parasites.

Daniel Thornhill, Coral Reef Marine Scientist

©Richard Ling

Whether it’s polar bears losing their icy habitats in the Arctic or corals bleaching in the tropics, climate change has drastically disrupted the lives of wildlife throughout the world. As our global climate continues to warm, wildlife species will respond with a “MAAD” set of options. Some will Move to a new home where conditions are less stressful. Others will adjust the way they live to Acclimate to the new conditions. Across generations, wildlife populations may even Adapt to the changing planet through natural selection. Too often when these responses are not an option, wildlife will Die as a result of climate change.

These changes are already happening on coral reefs. Reefs are home to more species than any other marine habitat on our planet, but this diverse environment is incredibly fragile. Reef-building corals — the very foundation of these shallow ocean ecosystems — are a delicate partnership between the coral polyps and microscopic algae. When temperatures become too hot, this partnership falls apart — a problem known as coral bleaching. Bleaching causes corals to starve, sicken and eventually die. This has already caused massive die-offs of corals throughout the world, leading the National Oceanic and Atmospheric Administration to propose 66 species of corals as threatened with extinction under the Endangered Species Act.

Despite this grim forecast, death is not the only option for corals. Recently, my colleagues and I investigated how corals respond to climate change. One of our findings is that average yearly temperature determined the northern limits of a coral’s range; if temperatures were too cold, corals could not grow. This is a bit of good news for corals — as warm temperatures push coral reefs away from the equator, many coral species will be able to shift north (or south in the Southern Hemisphere) from one generation to the next. Of course, other conditions must be right in order for this to happen. There must be enough light for the corals’ microscopic algae to thrive, hard surfaces for corals to attach themselves to, currents to move coral offspring to new places, and enough of the dissolved components of seawater that corals need to build their skeletons.

©Toby Hudson

We will need to take action on many levels to address climate change, from lowering greenhouse gas emissions  to planning ahead for a warmer world. Determining where wildlife can live helps us understand both how animals will naturally respond to climate change, and how we can give them the best chance at survival in an era of rising temperatures. Our study is an initial step in understanding these responses in corals.

Coral reefs are huge, immobile structures, but the corals that build them aren’t so static from one generation to the next. If we take action on climate change and learn what reefs need to survive, we can protect corals for generations to come.

by Daniel Thornhill

Ever gone to Google maps and used the “street view” feature to check out a new restaurant?  Or to see which side of the road an address was on?  Well, get ready to use Google maps in a whole new way.  Now you can view some of the most beautiful underwater landscapes on Earth, see fish species you never knew existed, and catch sea turtles napping amid beautiful corals.

Google has launched a new virtual photo tour of the Great Barrier Reef, one of the Seven Wonders of the World and the largest coral reef on the planet, as well as reefs in Hawaii and the Philippines.  The images were gathered for the Caitlin Seaview Survey, a global study of ocean and coral reef health.  There are currently 15,000 images, and by the time the mapping project ends in December, there’ll be about 50,000 available to view!

It used to be that only researchers like me had the opportunity to view and learn about so many different coral habitats and the species that depend on them.  Not anymore: now anyone with an internet connection can go to Google maps for an up-close and personal look at reef life in a growing collection of 360-degree panoramas. This is an unprecedented opportunity for conservation organizations like Defenders of Wildlife, to bring coral reef issues to the fore.

This reef at Dry Tortugas in the Florida Keys includes many different coral species and supports a myriad of fish, invertebrates and other animals. Photo courtesy of the National Park Service.

As a coral reef biologist, I’ve often needed to present the problems reefs face in an engaging way.  Visually documenting reefs is crucial to connecting them to the public.  While national parks and forests are accessible to everyone, coral reefs usually can only be seen in person by scuba divers.  The photos of the Great Barrier Reef and others are a “time-capsule” of the reef’s health.  Coral advocates can use them to educate people around the world, hopefully inspiring them to learn and care about coral reefs.

And coral conservation is more important than ever: climate change, pollution and other stressors are taking a toll on our planet’s reefs, as shown in these incredible “then and now” shots from Double Exposure, a photography site dedicated to showing how climate change alters our environment.  All too often, coral gardens that were vibrant and thriving 20 or 30 years ago are now pale and sparse.  Images are attention-grabbers, drawing viewers in and prompting the questions we researchers ask through our work every day: “how did this happen?” and “how can it be stopped?”

United States reefs in particular are suffering from major issues like overfishing, climate change, and nutrient pollution, which occurs when excess nutrients from waste water or agricultural runoff cause out-of-control algae growth, turning reefs into fields of seaweeds.  I saw first-hand how extreme frigid water temperatures in the winter of 2010 decimated reefs in the Florida Keys, killing corals that had survived for 300 years.  Lionfish, an invasive species that has made its way to the Atlantic coast, voraciously gobble reef-dwelling fish vital to coral ecosystems.  And the international coral trade for aquariums and curios has degraded reefs around the world, including our own.

The challenges that face our coral reefs are great.  But this project is a valuable new gateway to raising awareness about the plight of global coral reefs, and educating the public about how to stop the damage.

Defenders conservation scientist Dan Thornhill was the lead author of a study examining the effects of climate change on coral reefs in the Florida Keys last year- you can read it here.

Any scuba diver will tell you that the world’s coral reefs today are a far cry from what they once were. Climate change is leaving a permanent mark on these underwater jungles, a problem that only promises to get worse with time. Warmer water temperatures cause coral bleaching, a sudden death that occurs when corals expel the algae that normally live inside them, providing them with food and bright coloration. Warmer oceans also make corals more susceptible to bacterial and fungal infection, such as black band disease and purple blotch disease.

Rising temperatures aren’t the only threat facing reefs today. Overfishing, the explosion of invasive species, and an unsustainable aquarium trade all threaten the survival of these biological marvels, as well as the economies that rely on them. With the odds stacked against them, is there anything we can do to save coral reefs before it’s too late?

Wildlife biologist and Defenders’ board member Jeff Corwin, along with the Georgia Aquarium, is determined to find out.  Watch a sneak preview of his show, “Ocean Mysteries“ below and join Jeff as he explores one of the world’s majestic reefs, and what hope they have for the future.

Learn more: 

Hear more from Defenders’ board member Jeff Corwin as he talks about the world’s coral reefs – and how climate change is slowly killing these magnificent hotspots of biodiversity.

Defenders is working with other conservation and humane advocates to make sure the international trade in coral reef animals is done is a safe, sustainable way. Stay tuned for more on our efforts to protect the world’s reefs and the array of wildlife who call them home.

Ocean Mysteries with Jeff Corwin airs on Saturdays at 11am. Check your local ABC listings for more details.

A weekly homage to endangered species, large and small.

Photo courtesy of NOAA

Coral reefs are the ocean’s jungles, teeming with biodiversity unlike anywhere else on the planet. Warm tropical waters create ideal living conditions for coral polyps, the tiny creatures that secrete limestone and thus build the world’s coral reefs. These coral systems are extremely rare, occupying less than one tenth of one percent of Earth’s oceans, yet they contain an estimated 25 percent of all marine species (see wiki citation).

That’s why the rapid decline in health of the world’s coral reefs is so devastating. For example, elkhorn and staghorn corals have declined by 90 percent just in the last 30 years, landing both species on the endangered species list in 2006. And another 82 species are likely to be considered for federal protection under the ESA in the next year. These coral species have been wiped out by disease which has been aggravated by hurricanes, predation, bleaching and the increasingly damaging effects of global warming, which is both raising the temperature and acidity of our oceans.

The loss of coral reefs is not just a conservation concern, however. Hundreds, if not thousands, of businesses on Florida’s southern coast benefit from coral-related tourism. Each year, tourists flock to southern Florida for fishing, diving, snorkeling and boating tours along the coral reefs that add more than $4 billion to the region’s economy. This boom provides an estimated 70,000 jobs with a total payroll of more than $1 billion. (See NOAA report, Socioeconomic Study of Reefs in Southeast Florida)

Healthy coral reefs are the basis of a sustainable fishing industry. Photo courtesy of Krista Schlyer/Defenders of Wildlife

Coral reefs also provide a number of ecosystem services that we are only beginning to fully appreciate. The value of fisheries alone has been estimated to be worth between $15,000 and $150,000 per square kilometer, depending on the type of fish available (see pg. 12 of coral reef management sourcebook). Harder to quantify are the value of storm protection, erosion control and sand replenishment, all provided by coral reefs essentially free of charge. (See UNEP report, In the front line: shoreline protection and other ecosystem services from mangroves and coral reefs.) Without healthy reefs along the coast to dissipate waves and create more sand, the costs of storm damage, beach cleanup and finding more sand would all skyrocket.

The biodiversity along coral reefs is so high that they are also a promising place for pharmaceutical development. These hotbeds of sea life force creatures to eke out a living in close proximity to each other, where the ongoing battle for survival is almost always won by chemical weaponry, creating just the kind of proving ground biochemists dream of. This relatively new field of research is already producing results with the discovery of a potential replacement for the popular cancer drug Taxol—which coincidentally comes from another endangered species, the Pacific yew tree.

Protecting coral reefs ensures that we can continue to probe its makeshift laboratory for miracle cures, provide food and jobs for our families, and maintain our first line of defense against storm damage. Now that’s getting a lot of bang for our buck.

Learn more about the value of coral reefs in Defenders’ report, Conservation Pays: How protecting Endangered and Threatened Species Makes Good Business Sense.

Defenders' coral scientist Dan Thornhill in action

Whether you’re loading up a scuba tank or slipping on a snorkel mask, if you’re touring a coral reef, chances are you’re entering tropical waters. But what happens when suddenly those waves aren’t so warm? According to new research, it isn’t only rising temperatures that pose a threat to undersea ecosystems–a plunging thermometer could have serious consequences for corals as well.

Last year was an unusually frigid time for Floridians. In fact, January and February of 2010 saw temperatures on inshore reefs in the upper Florida Keys fall below 54 degrees F (12 C), and remain below 64 degrees F (18 C) for two weeks. The negative effects were felt by wildlife throughout Florida waters, and corals were no exception. Just three weeks after the cold snap, a team of researchers (including coral scientist and soon-to-be-Defender Dan Thornhill) headed down to the Florida Keys. They knew such a low drop would have an impact on corals found in the area’s reefs, but had no idea what they were in for. The results were chilling.

Corals from Admiral Reef before and after the cold-water event. Credit: Dustin Kemp, University of Georgia

Key Largo’s Admiral Reef was dead. “It was the saddest thing I’ve ever seen,” said University of Georgia researcher Dustin Kemp. “The large, reef-building corals were gone. Some were estimated to be 200 to 300 years old and had survived other catastrophic events, such as the 1998 El Niño bleaching event. The severe cold water appeared to kill the corals quite rapidly.” How had the cold hit them so hard, so quickly?

After comparing coral samples from those that had survived, the researchers determined that the key element was Symbiodinium, a type of symbiotic algae that lives inside corals and provides them with nutrition. Cold waters restrict the algae’s ability to photosynthesize (the same way excessively warm waters do). Without that vital energy, neither algae or corals can survive. And without corals, an entire ecosystem hangs in the balance.

“The corals provide the framework for the entire reef ecosystem,” Kemp said. “The lobster, shrimp, clams, fish — all the creatures that depend on the reef — were affected too. The potential consequences for coral ecosystems are extremely alarming.”

Learn more:

Cold temperatures join a growing list of threats to coral reefs around the world today. See how Defenders is working to protect protect the health and unique beauty of coral reefs by reforming the the unsustainable aquarium trade.

Dan Thornhill and his team of researchers are also working to process data gathered a mile below the surface before, during and after the BP Deepwater Horizon oil disaster to see how deep-sea animals and ecosystems fared after exposure to massive amounts of oil and chemical dispersants.

Feeling the Heat: See Defenders’ board member Jeff Corwin talk about the world’s coral reefs – and how climate change is slowly killing these magnificent hotspots of biodiversity.