Why Are We Killing Coral Reefs

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Why Are We Killing Coral Reefs?

Coral reefs are likely to become the first ecosystem completely destroyed by humans, predicts Dr. Peter Sale, a leading United Nations ecologist.  His new book, Our Dying Planet, explains:

“It is not pollution, or overfishing, or mass bleaching, or climate change, or any of the other factors I have mentioned that is killing our coral reefs.  It is all of these factors together.  Or, to put it more plainly, the cause of the destruction of coral reefs is us.”

Sale's conclusion echos the immortal words of cartoonist Walt Kelly, “we have met the enemy and he is us.”  The only possible silver lining is that we still have the power to reverse course and save at least some of these magical living communities.  But, change must come quickly.

While the extinction of an entire type of ecosystem sounds terrible, what are some of the specific ramifications?  In other words, why should we care?  Well, for one thing these beautiful ocean oases teem with some of the most stunning and fascinating creatures on the planet. 

Ever hear of the reef stonefish (Synanceia verrucosa) (above left)?  It’s the mostpoisonous fish in the sea, equipped with 13 venom-filled spines.  Camouflaged to blend into the surrounding reef, the stonefish waits for its prey to unwittingly swim past and then strikes with incredible speed.  You don’t want to step on this mottled creature.  

You may have spotted a mandarinfish (Synchiropus splendidus) (above right) on a dive trip or in a fish tank.  They’re tiny creatures, measuring only an inch or two.  But, what they lack in size, they certainly make up for in beauty and charisma.  Females often congregate in groups of three to five just before sunset, as interested males come by and strut their stuff.  When a match is made, the female balances on the male’s pelvic fin and the joined pair rises in the water above the reef, climaxing in a cloud of eggs and sperm.

On the other end of the size spectrum are the giant groupers (above left), which can grow to over 800 pounds.  Check out my earlier blog on these amazing behemoths. 

Another fascinating beauty is the queen parrotfish (Scarus vetula) (above right), which change color and gender over its 20-year lifespan.  Its bedtime ritual includes coatingitself in a clear cocoon of mucus secreted from an organ in the fish’s head.  It’s believed that the bubble masks the parrotfish’s scent allowing it to sleep free of the fear of predators.  

Coral reefs are one of the most biodiverse marine ecosystem on the planet – even more than tropical rainforests.  Although they only cover about 0.2% of the world’s oceans, they’re home to about one quarter of all marine fish species.  This dense biodiversity offer a treasure trove of life-saving medicinal compounds.  The active ingredients of some recently-approved drugs were discovered from organisms living within coral reefs, including Halaven, a drug to treat breast cancer that was derived from sponges (below left) found in coral reefs off the coast of New Zealand, and the prescription pain medication Prialt, which was derived from the cone snail Conus magus (below right) found in tropical reefs worldwide. 

Around the world, an estimated 275 million people depend on coral reefs for sustenance and jobs, with estimated economic benefits ranging from $30 to $375 billion per year.  Coastal populations also depend on healthy reef structures to protect them—studies have shown that healthy coral reefs provide twice as much protection from tsunami waves as dead ones, since healthy reefs are better able to absorb pressure from the waves.  More than 90,000 miles of shoreline in 100 countries benefit from this protection. 

Despite these benefits, our addiction to fossil fuels is releasing unprecedented amounts of heat-trapping greenhouse gases like carbon dioxide (CO2) into the atmosphere, which in turn is causing temperature rises that lead heat-sensitive reefs to bleach and eventually die.  Increased CO2 in the atmosphere is being absorbed by the oceans, causing the pH balance to become more acidic than many organisms are adapted to (see more on ocean acidification here, including NRDC's award-winning film Acid Test).  Overfishing, land-based pollution, and habitat destruction are further stressing already weakened coral reefs.

So, what can we do to avert catastrophe?

The dual threats of bleaching and ocean acidification require comprehensive climate change solutions, including renewable energy policies that reduce the amount of greenhouse gases released into the atmosphere.  Here are ways you can help.  As far as overfishing goes, in U.S. waters, the Magnuson-Stevens Act now requires strict, science-based catch limits to prevent overfishing, although these provisions are also under assault (see my blog describing the threat).  Globally, overfishing in and around coral reefs is an even bigger problem.  In addition to calling for improved fisheries management, we can all take immediate action to stop eating unsustainably caught seafood (visit our sustainable seafood guide to learn more).

We need to act now so that our children aren't left without the splendor of this invaluable ecosystem.

Photo Credits (from top to bottom and left to right): 1. Orange-lined triggerfish (Balistapus undulatus), humbug damselfish (Dascyllus aruanus); and blue-green chromis (Chromis viridis) by Jan Derk, Fihalhohi, Maldives, March 2006 (Wiki Commons); 2. Reef stonefish (Synanceia verrucosa) by Richard Ling, Ribbon Reefs, Great Barrier Reef, December 2006 (Wiki Commons); 3. Mandarinfish (Synchiropus splendidus) by Luc Viatour,www.Lucnix.be, Aquarium-Muséum Liège (Belgium), March 2008 (Wiki Commons); 4. giant grouper (Epinephelus lanceolatus) by Diliff, Georgia Aquarium, January 2006 (Wiki Commons); 5. Queen parrotfish (Scarus vetula) by Laszlo Ilyes, laszlo-photo, April 2006 (Wiki Commons); 6. Sponge (Halichondria okadai), http://kanagawa-yc.jp; 7. Conus magus by Richard Parker, November 2009 (Wiki Commons).