Left: What a healthy staghorn coral looks (photo: flickr). Right: Bleached staghorn coral (photo: Wikipedia)

Why we can’t have nice things: Great Barrier Reef edition

The Great Barrier Reef, which some consider to be the greatest natural wonder on Earth, is in serious trouble. Occupying an area close to the size of Italy, scientists are reporting widespread bleaching in the northernmost sector of what is considered the largest living structure in the world. This is particularly alarming because after bleaching events in 1998 and 2002 hit the central and southern portions of the reef, the northern sector was considered one of the last pristine areas for coral in Australia.

What is coral bleaching and why is this happening?

Coral is two different species working together for their mutual benefit – what biologists call a symbiosis. This symbiosis consists of a polyp,a tiny animal that looks like an upside down jellyfish, and a single celled algae called a zooxanthelle. Together, they make great roommates: the algae provides a source of food and oxygen for the polyp through photosynthesis and in return the polyp gives the algae carbon dioxide and a place to live. It’s why reefs grow in clear, shallow water. The algae need sunshine for photosynthesis. Each piece of coral that we see is actually a colony of thousands of these pairs living together.

zooxathanthae
Coral polyps with their green, photosynthetic zooxanthellae living inside. Photo Credit: International Union for the Conservation of Nature

The Earth’s temperature has been increasing steadily over the past 80 years. Of the several resulting problems, coral bleaching is one. Like in many chemical reactions, increasing the temperature will increase the rate that reaction occurs. Since ocean temperatures have increased across the world, the algae that live within coral reefs are performing their photosynthesis at faster rate, producing more oxygen. The problem with this is that while oxygen is essential for polyps to live, excess oxygen is toxic. So as ocean temperatures have gotten warmer, the polyps have been kicking out the algae to keep from being poisoned by the excess oxygen. When this happens, not only do the corals lose their brilliant colors and become bleached and white, the polyps lose an important food source, making them much more susceptible to disease.

The newest study by the National Coral Bleaching Taskforce showed that of over 900 reefs surveyed, only 68 were healthy. In addition to the 93% of coral on the Great Barrier Reef being bleached, nearly half of the coral is either dead or dying.  Terry Hughes, director for the ARC Centre of Excellence for Coral Reef Studies at James Cook University called his latest aerial survey “the saddest research trip of my life“.

coral bleaching.png
Photo Credit: Science Over Everything

That’s so sad! How does this effect me?

The Great Barrier Reef is home to a huge amount of biodiversity.  Occupying less than one percent of the ocean floor, coral reefs are home to more than twenty-five percent of marine life. There are literally thousands of different species that call this amazing place home, including nearly 1,500 different species of fish, 411 types of hard coral, 134 species of sharks and rays, 3,000 mollusks, 630 species of echinoderms (starfish and sea urchins), 6 species of marine turtles, 215 species of bird, thousands of different sponges, worms and crustaceans, and more than 30 species of marine mammals. Additionally, the Great Barrier Reef brings in about $5 billion USD a year in tourism revenue to Australia. The industry as a whole is about 2.5% of Australia’s GDP. A fatally damaged reef would be a huge blow to their economy.

To put some of those numbers in perspective, the Great Barrier Reef provides a habitat for about 10% of the total marine fish species and one third of all soft coral species in the world.  Losing that level of biodiversity goes beyond the extinction of a few species. Many ocean species call the Great Barrier Reef home for a only a few months out of the year, then move on to other parts of the world to breed or hunt. A collapse of the reef would have devastating effects across the entire ocean food web. If the Great Barrier Reef were to vanish, one could only guess at the repercussions.

If you are looking to help save these amazing habitats, there a couple easy things that you can do to help protect coral reefs, even if you don’t live anywhere near them. By leaving your car at home and taking a bike or a bus to work just two days a week, you can reduce your greenhouse emissions by 1,590 lbs a year. Reducing water consumption, recycling, buying local food and goods are all great ways to cut down waste and carbon emissions. If you’d like to get even more involved, there are also several groups that organize reef clean ups and Nature Conservancy has an adopt a reef program. But perhaps the most important thing you can do is spread the world. Creating awareness of these beautiful environments and how dangerously close we are to losing them, is the only way to make broad policy changes.

Leave a Reply

Your email address will not be published.


*