By on August 31, 2012 in Africa, Environmental, Wildlife

No Grief on this Reef

Coral reefs have become synonymous with environmental disaster since a global warming caused bleaching event wiped out over 10 percent of the world’s reefs in 1998.  Now the good news: Super reefs off Kenya’s coast have shown resistance to bleaching and may hold answers for reversing reef decline globally.

In 2009, Dr. Tim McClanahan, a marine biologist working for the Wildlife Conservation Society, published his Africa super reef thesis, creating a stir in the marine biology community.  After 30 years of studying reefs throughout the Indian Ocean, McClanahan and his Kenyan marine biologist wife, Dr. Nyawira Muthiga, found that reefs off the southern Kenyan and northern Tanzanian coasts were showing resistance to bleaching by recovering much quicker than other reefs around the world.  The 1998 bleaching event destroyed around 45 percent of the Tanz-Kenyan reefs, but these African waters have highly variable current flows and water temperatures that allow the elevated reefs to adapt to sudden changes in acidity and warmer ocean temperatures.  In less than a decade, these reefs have made a strong comeback.

An important defensive characteristic of the Tanz-Kenyan reefs was a well-managed fishing industry through government regulations and enforcement.  Educational forums and tourism also play a role in protecting these reefs.  Dr. Muthiga’s years of establishing Kenya’s marine programs have played a big part in safeguarding the reefs.  A healthy fish population is critical to the reef’s survival.  The multi-hued reefs off Kenya’s southern coast are brimming with parrot, sturgeon, and rudder fish that munch excess algae that could choke reefs.  A dangerous imbalance occurs when there is an abundance of sea urchins and a lack of key algae eating fish, but these super reefs have fewer urchins than less healthy reefs.

There are 250 species of fish in these waters and over 100 species of coral on a single reef.  While highly diverse, the most biodiverse reefs in the world are located north of the Great Barrier Reef in the Philippines and Papua New Guinea; but bleaching and coral mining have taken a heavier toll there than the Tanz-Kenyan super reefs.

Not All Reefs are Alike 

Since McClanahan’s 2009 super reef discovery, he has been surveying the seas from South Africa to the Maldives looking for patterns and seeing how his super reef theory has been holding up.

“The southern reefs are doing pretty well and have actually recovered more in the last two years.  Conditions there are more like they were historically.  The northern reefs in Kenya, the Seychelles, Maldives, and Madagascar took the biggest hits from bleaching and have shown spotty recovery,” McClanahan said during a phone interview with Tusker Geografica. “The biggest hope is we can replicate positive environmental conditions and keep the fishery in good shape.”

McClanahan’s research shows temperature ranges of 24 to 30 degrees centigrade during a tidal cycle on the super reefs, enabling them to be resistant to bleaching that is caused by sudden ocean temperature rises and increased acidity.  Reefs lose their color and turn a ghostly white during bleaching events that kill these living corals.  Reefs that sit in waters where there is little temperature change are more vulnerable to bleaching.

His research shows that reefs that are closest to villages are often fished heaviest and have the least healthy reefs.  “Our offshore gradient pattern research shows the reefs further offshore, 30 kilometers out, are doing better than reefs 7 to 9 kilometers from shore.  McClanhan fears the African international waters are being heavily fished by foreign trawlers, and he is watchful.

“I see the distant lights well offshore, and I suspect there has been more government contracts to allow trawlers. But a lot of that information is not public. It’s an ongoing problem.”  Reefs are typically closer to shore.

Kiseti: Super, Super

To see a super reef in all its kaleidoscopic color and liquid life, visit Kiseti Marine Park in Kenya.  Above the reef, rare humpback dolphins slice through the water with their young.  European migrants, roseate terns, and crab plovers fly above the four small islands that surround the reef, ever alert to dive on small fish and crabs.  In the water, reef sharks, manta rays, and giant sea turtles are singular sensations, while schools of red and yellow tuna are a piscatorial parade feeding in small schools on the reef.

And then there is the coral garden.  Brain, staghorn, and mushroom corals are of interest for their shapes, but the lilac blue and lavender corals can bring a joyful tear and mist inside the diver’s mask who has an ascetic sense for these global treasures.

Declared part of Kenya’s Park Service in 1978, these reefs have benefited from a combination of government oversight, tourism, and the continuing interest of NGOs such as Wildlife Conservation Society.  The park is located 75 miles south of Mombasa, just six kilometers offshore and has no hotels or fresh water.  Campers arrive by community dhow and haul their own gear.  A few small local companies arrange day tours, but the park is among Kenya’s most spectacular and least visited.  Many tourists come to Kenya to bag the big five and leave it at that, but they miss a lot by not snorkeling or diving on a super reef.

McClanahan has been part of Kiseti’s success for three decades.  “Kiseti was disturbed by the 1998 bleaching episode but bounced back quickly, and its status today is good.  There is no fishing there, and the government patrols it every day.  A ranger is posted on the island and sleeps there.  This keeps the park from being poached.”

Fish Forums and Sperm Banks

McClanahan and Muthiga have worked to integrate the local communities with marine conservation.  It’s been a two-decade project, and McClanahan said the tide has turned.  For the last 17 years, McClanahan has held forums with fishing leaders trying to reduce fishing and change the way fisherman work around the reefs.

“They used to be aggressive and argumentative about the concept of conservation, but now the concept has sunk in.  They have tried our suggestions, and there is a positive feeling they are willing to participate in conservation,” McClanahan said.

In looking across the Indian Ocean, McClanahan has highest hopes for Reunion’s reefs to rebound.  These reefs have been hammered by too much tourism and a deadly flow of shore sedimentation that has hurt the corals there.  Reunion is a French held island and the furthest outpost in the European Union.  McClanahan said that the French have imposed monitoring programs and established protected marine sanctuaries since 2007 in an effort to return these reefs to their formal colorful glory.

Elsewhere around the globe, reef restoration projects are taking high-tech approaches that offer hope that less biologically adaptable reefs can survive future bleaching assaults.  Coral sperm is being frozen at the Hawaii Institute of Marine Biology where Dr. Mary Hagedorn is building the world’s first coral sperm bank.  Hagedorn’s bank contains a trillion coral sperm gathered from the Pacific, the Caribbean, and Australia.  She hopes someday to use this frozen sperm to rebuild damaged reefs around the world.


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