The Great Barrier Reef: What You Need to Know About Coral Bleaching

July 12, 2016

Stretching over 2,300 kilometers along the Queensland coastline, Australia’s iconic Great Barrier Reef – the largest coral reef system in the world – is at stake. According to a report from Australia’s National Coral Bleaching Task Force, which has just completed an aerial survey of the more than 500 individual reefs from Cairns north to Papua New Guinea, 95% of coral reefs is suffering from severe bleaching, with around 50 percent of the coral already dead or dying. The Great Barrier Reef- one of the seven wonders of the natural world -is on the brink of extinction.

The Great Barrier Reef is a World Heritage Site

The Great Barrier Reef comprises roughly three thousand individual reefs and one thousand islands and cays, and covers an area of about 348,000 square kilometers, making it larger than the United Kingdom, Holland and Switzerland combined. In fact, this natural icon is so large and vast that it is visible from outer space – for decades, many scientists have spent their lifetime exploring the reef, but none of them is able to view it all.

The Great Barrier Reef is also unique as a center of marine diversity. The reef contains 600 types of soft and hard corals, more than 100 species of jellyfish, 3000 varieties of mollusks, 500 species of worms, 1625 types of fish, 133 varieties of sharks and rays, and more than 30 species of whales and dolphins, which make the reef one of the most complex natural ecosystems in the world.

Worst-ever Coral Bleaching

Coral bleaching is caused by warming ocean temperature. The survival of corals depends on the photosynthetic microalgae (zooxanthellae) living within their tissues, which provide corals with nutrients and incredible colors. When corals are under stress due to increased ocean temperature or pollution, corals will expel the zooxanthellae and turn to a lighter or completely white appearance, hence the term “bleached”. The process does not kill the coral immediately, but leaves it in a vulnerable and stressed state: If the balance is restored, the bleached corals can bring in new zooxanthellae and recover (but it can take decades!); if the stress condition persists, the corals will be overwhelmed by brown-green algae and other organisms and will die eventually.

The current massive bleaching event is the worst ever been in the history. The Great Barrier Reef has experienced two major bleaching episode in recent decades, with 42 percent and 54 percent of corals being affected by bleaching in 1998 and 2002, respectively. Nevertheless, the extent of the bleaching during these summers is no match to this year’s record.

Effects of Climate Change

The strong El Nino weather that has swept across the Pacific Ocean Region last year is partly to blame for the massive coral bleaching, but the major culprit is global warming. Coral bleaching is considered “the most widespread and conspicuous impact of climate change”, according to the U.N.’s Intergovernmental Panel on Climate Change (IPCC). As climate change raises ocean temperature and causes ocean acidification, now more than ever the Great Barrier Reef is under the threats of stress-induced coral bleaching.

Also, the future is bound to be even riskier for the Great Barrier Reef, as IPCC’s climate change projection models indicate. If global emission of greenhouse gas continues to grow at its present rate, the concentration of carbon dioxide in the atmosphere will exceed 600 ppm by the end of the century – approximately 2 degrees Celsius increase in ocean temperature. The steady rise in ocean temperatures projected for the next few decades is lethal to the Great Barrier Reef, as the thermal stress exceed the corals’ tolerance threshold. In fact, IPCC predicted that the Great Barrier Reef will be “functionally extinct” by 2050.

Coral destruction has great impacts on the region’s biodiversity and economy. Coral reefs are important habitats for a magnificent diversity of species, including tropical fishes, mammals, reptiles, and birds. As corals die off, the number of species that relies on the coral reefs declines, diminishing biodiversity. In addition, continued bleaching events in the Great Barrier Reef can significantly harm the local economy, especially fishery and tourism. Great Barrier Reef Park contributes about AU$6.9 billion (around U.S. $6.4 billion) annually to the Australian economy. Without mitigation measures, Australia could be losing billions of dollars in potential revenue from the Great Barrier Reef.

Steps to Help Protect Coral Reefs

Want to know how to protect the Great Reef Barrier? Here is the right place! As the world heritage site, Great Reef Barrier is the richest, most spectacular marine ecosystem on the planet, and we are all entrusted with the responsibility to take care it.  Check out these eight simple steps to help preserve the precious coral reefs system and the species that depend on it. You can make a difference!

  1. Use less plastic: Plastic pollution is one of the biggest threats to the marine ecosystem. Switch to reusable shopping bags instead.
  2. Reduce your carbon footprint: Walk, bike or use public transportation. Greenhouse gas emissions from cars and industry contribute to global warming, which ultimately causes mass bleaching of corals.
  3. Dispose of your trash properly: Don’t leave things like unwanted fishing lines or nets in the water or on the beach. Littering can smother the corals and kills the fish that populate coral reefs.
  4. Support reef-friendly businesses: Be an informed customer. Make sure your dive shop, boating store, tour operators, hotel and other coastal businesses are caring for the living reef ecosystem and ask whether they have made any effort to save the coral reefs.
  5. Diving and snorkeling responsively: Keep your hands, fins and other gear away from the coral. Corals are extremely delicate. Even a single touch can damage or kill live corals.
  6. Volunteer for a coral reef cleanup: participate in local beach clean-ups and reef clean up programs. You can find volunteer opportunities on websites such as Heal the bayBlue Ventures and Oceans Watch.
  7. Use mooring buoys: do not anchor on the reefs. If you are boating near a reef, use mooring buoy systems when available.
  8. Spread the word: Educate your family and friends about the importance of coral reefs. Share your excitement and encourage others to get involved.


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