Priceless coral reefs
Without them The Bahamas would not exist
Priceless coral reefs
Without them The Bahamas would not exist
The reason there are islands rising from the shallow waters of the Great Bahama Bank is because they were put there–designed and built–by a strange little sea creature that does not have a discernable brain.
Coral polyps are small and simple–little more than tentacles to trap food, a mouth and a stomach. They spend most of the daylight hours hiding away in a hard exoskeleton they create by converting seawater into a hard calcium carbonate shell, which they cement onto the exoskeletons of their ancestors, forming reefs.
At night, the polyps shyly emerge, like debutantes at an evening ball, to dine on plankton tidbits passed around by the restless sea. These are slim pickings. In fact, The Bahamas’ ultra-clear water is so lacking in nutrients that the polyps would soon starve to death but for the assistance of a microscopic algae, called zooxanthellae, that lives within the polyps’ tissues. When the water around a reef becomes too warm, corals may expel their zooxanthellae, leaving a white (bleached looking) skeleton.
The zooxanthellae convert water and carbon into sugars, lipids and oxygen, which keep the polyp well nourished and energized, exacting in return its own sustenance and a safe shelter. It’s a good deal for both organisms in the unforgiving environment of the open ocean.
Most corals are small, about 3mm (1⁄10th of an inch) across but there are giants of 30cm (about 12 inches). But over geologic time they produce mighty works–including thousands of archipelagic islands and atolls around the world.
It is corals, along with their associated creatures, who also create The Bahamas’ talc-like beaches, upon which tourists love to shuck their sandals and stroll barefoot.
Depending on the species of nearby marine life, the beaches range in colour from sugar white to creamy beige to–on at least one famous beach on Harbour Island, Eleuthera–pink.
It would be difficult to overstate the importance of coral reefs to The Bahamas, or to the world at large. They are crucial to the well-being of the oceans and all those who rely on the sea for their livelihood, or who love seafood–which, by extension, includes just about everyone.
Referring to them as “rainforests of the sea” is more than a figure of speech for corals rival those terrestrial ecosystems in the diversity of life forms they sustain. Although they occupy less than one per cent of the oceanic environment, marine scientists tell us reefs shelter more than 25 per cent of all marine fish species.
“Coral reefs are some of the most diverse and valuable ecosystems on Earth,” according to NOAA, the US National Oceanic and Atmospheric Administration. They “support more species per unit area than any other marine environment, including about 4,000 species of fish, 800 species of hard corals and hundreds of other species.” As well, scientists estimate that there may be another one to eight million species of organisms, as yet undiscovered, living in and around reefs.
As home to an extensive network of reefs, including the third largest barrier reef in the world, along the east coast of Andros, The Bahamas bears a responsibility to ensure that they remain healthy and productive.
Lifeblood of the islands
Reefs grow slowly–about half an inch a year on average. “The only living part of a reef is its surface,” says Casuarina McKinney-Lambert, executive director of the Bahamas Reef Environment Education Foundation (BREEF). “Coral reefs are some of the oldest structures on the planet and one of the few you can actually see from space.”
They are home to many of The Bahamas’ most loved seafoods, including grouper, lobster and snapper. They are also a huge moneymaker for the tourism industry.
Visiting a coral reef is an amazing experience because corals take many different shapes, looking like shrubs, whips, fans, feathers, fronds, horns, plates, and even the exposed surface of a human brain.
“Having a healthy coral reef benefits us in so many ways,” says McKinney-Lambert, “People come to The Bahamas to dive and snorkel and they want to see something special. Thanks to the reefs we have turtles and sharks in these waters. People want to come and see these things. It’s such an important part of our culture.”
Reefs also reduce shoreline erosion during hurricanes and lesser storms. “People don’t think about that much until a storm comes along and they realize that if the waves were not breaking on the reef, they’d be breaking on the island,” says McKinney-Lambert.
Reefs are also of great interest to pharmaceutical firms who are continually bioprospecting the natural world for new drugs and medicines. Reef-based sponges, for example, have yielded anti-leukaemic and anti-viral agents, as well as the first effective treatment against AIDS, the drug AZT. Another reef inhabitant, the tiny cone snail, produces a powerful toxin that is widely used as a painkiller. In one of the latest developments, doctors are now using coral for bone implants and skeletal repairs because it does not activate the body’s immune system and integrates itself seamlessly into new bone growth.
Reefs are indispensable to The Bahamas, and that’s a worry to scientists because coral polyps face many threats. In fact, marine biologists warn that, without a big conservation effort, coral reefs could vanish from the sea within 50 years.
“There is so much we don’t know about the reefs,” says McKinney-Lambert. “We are still discovering new species and we want to make sure we don’t lose them before we know what we have.”
Scientists believe the earliest corals began to appear about 500 million years ago, although the ancestors of most modern species may have formed about 230 million years ago. Fossilized coral is a time machine for geologists, opening a portal into conditions that prevailed when the Earth was younger.
Researchers with the Woods Hole Oceanographic Institution, led by geochronologist William G Thompson, travelled to The Bahamas in 2011 to examine fossil corals that formed about 120,000 years ago.
The team’s main finding was that sea levels varied by greater amounts in the last inter-glacial period [a warm period, like the present one, between ice ages] than previously thought– rising and falling by 4m to 6m (about 13 to 20 ft) over 4,000 years.
“If today’s ice sheets continue to melt, we may be headed for a period of ice sheet and sea-level change that is more dynamic than current observations suggest,” Thompson says. These findings add to existing concerns about global warming. If the seas were to rise significantly, that would affect a critical set of conditions that determine whether corals can survive or not.
The ultimate sink
Aside from global warming, the main threats to Bahamian corals are local land clearing, pollution, overfishing and, most recently, an invasion of voracious Indo-Pacific lionfish that feed on native reef fish.
“Coral reefs are not a stand-alone issue,” says McKinney-Lambert. “Most of the threats in The Bahamas come from land. Any garbage on land has the potential to wash into the ocean,” she says.
“The reason coral reefs grow so well in The Bahamas is because our water is clear and really low in nutrients. With sewage and garbage washing into the ocean, there’s a problem with the reef being smothered.”
The main culprit is nitrogen, which spurs plant growth in seawater just as it does on land, especially a fleshy type of algae that can spread rapidly over a reef. This growth blocks the sunlight that would otherwise reach the corals and help them grow.
Overfishing is also a big problem in The Bahamas. Fish are integral to the life of the reef, they eat algae and keep species lower down in the food chain in check.
Removing fish plays havoc with the ecological balance of the entire reef. To combat this The Bahamas has established closed seasons for some species and imposed severe restrictions on the trade of others. Nassau grouper are not fished from November to February as this is when the fish breeds. Crab and crawfish also have closed seasons to allow their populations to regroup. As well, The Bahamas is establishing a network of Marine Protected Areas.
One fish that the government is keen on eliminating however is the lionfish. This species, which was accidentally released into the Atlantic in Florida, has spread to The Bahamas and the Caribbean. With no known predator in the Atlantic, lionfish can overwhelm a reef, eating the young of other species into extinction.
“Lionfish are a relatively new threat but they are eating some of our crucially important species as well as competing with some of our native species for food,” says McKinney-Lambert.
Saving the reefs
In April 2011, the Living Oceans Foundation chose The Bahamas as the starting point for its five-year study of the world’s coral reefs, which aims to pinpoint the major threats to reefs worldwide and identify practices to safeguard the ecosystems.
BREEF’s Alannah Vellacott, a local scientific diver who assisted with the Living Ocean Foundation’s research in Cay Sal and Inagua, says the expedition found healthy reefs there that highlighted the disparity between these undisturbed sites and reefs that experienced more human interaction.
“I was very much impressed by the live reefs in Inagua,” says Vellacott. “A lot of the coral present were alive and teeming with marine life, great and small. The biodiversity there had me amazed. Comparing the heavily trafficked area in Lucaya, Grand Bahama, to remote dive sites like the Family Islands, it really goes to show the amount of impact we have on our coral reefs.”
Over the past 50 years, the earth has lost 20 per cent of its corals, according to the foundation, and the Caribbean is one of the worst-hit areas. There, 50 to 80 per cent of coral cover has been destroyed over the last two decades. That includes the near extinction of two important reef builders: elkhorn and staghorn coral.
Now, thanks largely to the efforts of the Bahamian chapter of an international environmental group, The Nature Conservancy, the country is taking action to save these two corals in Bahamian waters.
In late 2011, The Conservancy established a coral nursery on the south coast of New Providence, much as they had done earlier in Florida and the Virgin Islands. Divers glue two-inch coral shards to discs called pucks and attach them to cement blocks. The Conservancy intends to place 500 blocks at each nursery site, which should lead to 5,000 healthy corals.
“Four years ago the idea was considered highly controversial. We are essentially farming corals to repair or replace damaged reefs that are degrading for several reasons. The coral nursery project also provides an opportunity to create coral to restore reef habitats to a healthier condition,” says Eleanor Phillips, director of The Conservancy’s northern Caribbean program.
It takes four or five years for the coral to attain a size that allows them to be transplanted to a degraded reef. The nursery coral is detached from its block, placed on the reef where both the coral and the puck are gradually integrated into the body of the reef.
Having the ability to renew reefs in this way is key to their survival and Phillips is eager to start nurseries in a few other sites in 2012. At the moment, the project is confined to staghorn and elkhorn coral from Bahamian reefs.
Although the basic materials for a nursery are inexpensive, the real cost lies in the manpower and labour required to build and maintain sites. Divers must visit the nursery once a month (more frequently if there has been stormy weather) to ensure that the corals are stable and to clean algae from the puck.
Volunteer divers–including some from The Bahamas’ largest dive company, Stuart Cove’s Dive Bahamas–The Bahamas National Trust and the Department of Marine Resources are working with The Nature Conservancy to maintain the sites. Phillips would like to see more Family Island communities, and even visiting divers, become involved.
“It could be a good economic generator for a lot of the Family Island communities,” she says. Locals can go fishing and look after coral at the same time. “By getting people to care for the coral we are expanding the knowledge base and sustaining our livelihood. Healthy reefs mean healthy fisheries.
“One of our ideas for the future is also to have tourists come out on an eco-dive and help us clean the corals. In return, they get a lesson in coral ecology. There are a lot of opportunities with the nursery.”
Whether it’s divers volunteering at a coral nursery or boaters simply being careful where they drop anchor, visitors have a role in reef conservation.
Millions of visitors come to The Bahamas each year and many of them will take to the water at some point. Minimizing your footprint on the undersea world is important, says McKinney-Lambert, who cautions snorkellers to be especially careful when swimming over corals because even a slight contact can cause damage.
BREEF advises tourists that all hard coral is protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This makes it illegal to buy coral products in The Bahamas and take them home.
Growing up on Eleuthera and swimming from a young age, McKinney-Lambert is passionate about the marine environment and believes there needs to be a better balance between human interests and the reef’s wildlife.
“I do a lot of spearfishing and I see the reef as a resource that we can use but something we cannot use up,” she says. “The issue of protecting our environment is something that is really going to affect the next generation–they are going to be the beneficiaries … and those who suffer if we do not do a good job.”
Information in editorial and listings is subject to change at any time.