What is the Great Barrier Reef?
At approximately 133,000 square miles, the Great Barrier Reef, located in the Coral Sea off the coast of Queensland, Australia, is the largest living structure on Earth--so large, it can be seen from space. Not only does it contribute more than $6.4 billion a year to the Australian economy today, but it has also been a part of Australian culture for nearly 60,000 years. Hosting 10% of the coral reef ecosystems globally and proudly holding the title of the “most complex natural system on Earth” according to the Australian government, it is also home to a vast array of marine wildlife (2).
Thirty species of whales call the reef their home; 133 kinds of sharks and rays do as well. There are also over 1600 types of fish, 500 species of worms, and even 3000 varieties of mollusks (2). And, to answer your question, yes. This is where Nemo, Marlin, and Dory live. The Great Barrier Reef, while massive, is one stunning example of the world’s coral reefs and the complex ecosystem within them.
The Fascinating World and Benefits of Coral
When it comes to just how many creatures live in the Great Barrier Reef, one of the most recognizable creatures is one that you may not have thought was alive--coral. Often looking like a collection of large flower vases on the ocean floor, coral is frequently mistaken for being some kind of plant. Think of coral as a large marine LEGO set--at the beginning, there is only one piece. Then you add another piece, then another, and another until, eventually, there is a finished model. Most coral is made of hundreds of thousands of tiny soft-bodied organisms called polyps stacked on top of one another like LEGOS.
Every polyp has an exoskeleton made of calcium carbonate and sodium, and they use it to attach to various marine objects, like rocks and even dead polyps, which creates coral. When polyps die, their exoskeleton stays, allowing other polyps to make a home on top of the dead polyp. The cycle is repeated for decades, centuries, and even millennia. Zooxanthellae (zo-UH-zan-thuh-lay), tiny marine creatures, also make homes of the dead polyps and make their food through photosynthesis with the aid of metabolic waste released by the coral (3).
Some species of coral, determined by what kind of zooxanthellae calls it home, can be as large as a two-story house, while others can be the size of a chicken egg. From table coral to foliose corals to Mushroom corals, they all play an essential role in the world both below and above the surface (6). While coral reefs only make up about 1% of the ocean floor, on average, they host over 1 million marine species, meaning they support an estimated 25% of all marine life. Coral reefs even protect shorelines and coastal populations worldwide from large storms like hurricanes and tsunamis. Their density acts as a buffer against the immense wave energy below the surface (4).
In addition, coral reefs are very beneficial in terms of tourism that supports billions of dollars and millions of jobs worldwide. It is estimated that coral reefs provide over 1 billion people with food supported by fishing. Furthermore, thanks to their incredible biodiversity, it is thought that many different species of coral are capable of providing humans with life-saving medicines and treatments against the most potent illnesses on earth (4). All these factors put a monetary value on the world’s coral reefs of about $172 billion (but, of course, they are priceless relics of our planet) (5).
From pink to blue and from yellow to red, these amazing corals come in a vast array of colors, based on what kind of zooxanthellae is present. However, a newer color has become more and more present all around the ocean--white.
Overfishing
Fish, of course, play an essential role in the coral reef system. Even as fish feed off the coral, possibly damaging it, there is a natural balance in the marine circle of life. This means that significant threats occur when fish are taken away due to overfishing. When older fish are taken from the ocean, their potential offspring leave, as well; when fish young and old are taken from their natural habitats, fish populations decrease over time. Even when new fish are born, they can still become entangled in shallow shore nets. When the population of young fish decreases more and more by the day, it becomes impossible to sustain their population. When there are fewer herbivorous fish due to nets and traps, there are fewer fish able to eat algae and other similar organs that, if out of control, cause the natural balance to dwindle, too. Then, the impact is felt on the shore. The fewer fish there are, it becomes more difficult for anglers to catch fish, sell fish, and help local economies (8).
Dredging and Development
With one-third of the world living in coastal areas, there is a high need for development and infrastructure near coral reefs. When waterways, ports, and harbors are created, coral reefs may get buried or entirely removed due to the high levels of turbidity as water loses its transparency due to how many particles are present until they settle (9). Dredging, or the “process of excavating sediment deposits, trash, and other debris from the harbor floor and disposing of them elsewhere,” is a leading cause of these microparticles suspended in the water. And while dredging does prevent floods, removes contaminants, and restores some ocean health, the impacts of people trying to solve pollution from the past are causing the coral reefs of today to die (10).
Particulates in the water form large clouds that block sunlight. Less sunlight then leads to less photosynthesis which leads to difficult living conditions for zooxanthellae. This can then lead to less coral which, in time, leads to less food for marine creatures. The ships used for dredging can also scrape against reefs, causing the coral to break and die (9).
Plastic Soup
But then, of course, dredging wouldn’t be needed if it weren’t for an overabundance of plastic material, this overabundance having the nickname “Plastic Soup,” and being present all over the ocean and coral reefs. There is such an enormous plastic soup issue present that there are five garbage patches in the ocean, the most famous being the pacific garbage patch which stretches from the California coast to the Hawaiian Islands. With the patch being influenced by winds and currents, it is nearly impossible for scientists and researchers to pinpoint just how large the patch is and just how many pieces of debris are present. In fact, with such a variety of plastics, some portions of the patch contain large items like water bottles and fishing nets, and some areas look empty but are filled with microplastics and items that have been dragged under the surface.
A four-year diving study that saw scientists and researchers diving into 159 pacific ocean reefs in Australia, Thailand, Indonesia, and Myanmar proved one thing--plastics are a reef’s worst nightmare. Not only was it discovered that the chance for disease in coral reefs jumps from 4% to 89% when plastic is present but also that there are four individual coral diseases present when plastic comes into contact with reefs. The causes of the diseases are unclear, making them very unpredictable. Where plastics cause disease, they also cause abraded or ripped, coral. Plastic clings to the coral, and it “basically tear[s] open the skin of the coral, and that can allow an infection from anywhere to start,” due to the number of bacteria and harmful microorganisms, which coral was originally protected from, now being allowed to conquer the coral (11).
These factors play key roles in coral bleaching, with climate change and global warming being the leading causes.
Coral Bleaching and Its Impacts
The above issues cause the zooxanthellae living on the coral to disburse, leaving only the coral’s white, dead exoskeleton behind. Keep in mind just how essential coral is to the marine ecosystem; it not only provides food but shelter to various organisms, including at-risk species near extinction (12). Bleaching not only impacts corals but all animals or plants that need microscopic algae to survive. Take, for example, the sea anemone, the most vital part of the life of a clownfish. From October 2015 to December 2016, research was conducted on clownfish in French Polynesia.
It was discovered that clownfish living in bleached anemones had an immense amount of cortisol, the stress hormone, in their blood which caused a decrease in sex hormones and the fertility of the clownfish as well as a 73% reduction in egg production. It is important to note that the research was conducted during El Nino, the recurring and natural warming of the ocean, as irregular natural warming can cause bleaching as well. Still, it is important to think about how much worse the ongoing effects of human interaction and global warming will be in the future.
“It’s very confronting to see the scale of the bleaching, and to know that you’re going to lose a lot of corals on the heavily bleached reefs,” stated Terry Hughes, director of the ARC Centre for Coral Reef Studies at James Cook University in Australia (13). It was recently reported that the Great Barrier Reef saw coral bleaching present from the Torres Straits to the Bundaberg--about 2,000 km or 1,250 miles. Since 1995, the Great Barrier Reef has lost half of its corals, and, as of now, scientists and researchers are unsure what to expect in the future. It is very difficult for corals to recover from bleaching… but what about the animals? Will the stress seen in clownfish and many other creatures help them adapt to a new ocean phase if coral bleaching and ocean pollution continue? Or will marine extinction become a much more common occurrence?
How Can We Protect Coral Reefs?
Luckily--in the worst way possible--coral bleaching can be seen, causing it to be better believed than other phenomena like global warming. This has produced more direct action. In fact, scientists in Australia have developed ways to help the Great Barrier Reef’s bleached areas. One way to do so is to collect bleached coral structures and move them to an underwater nursery then move them back to their natural habitats once they have grown to a suitable size. Some coral structures are put into large horse-trough-like tubs that circulate the water to and fro inside, simulating the coral’s natural habitat and allowing beneficial particles to be fed on by the corals. These two methods are very beneficial as, while bleaching continues to be an issue and coral structures continue to die, there is already a population of corals ready to take their places. However, these recycling plans can easily be thwarted if things continue to get worse and worse (15).
One way YOU can help slow the bleaching is by ensuring the fish you eat or keep as pets were collected sustainably, limiting overfishing. You can always check if the company you are purchasing your fish from has a Marine Stewardship Council, a complicated certificate to earn that proves the fish were caught sustainably. You can even check nutritional facts as fish distributed from farms will be exposed to fewer chemicals and, thus, far healthier (14). When it comes to plastic soup, make sure that you are recycling as much as possible. As for the trash that cannot be recycled, make sure you are disposing of it properly in bins, lowering the chance for plastic to be blown into waterways and the ocean.
You can also minimize your use of fertilizers, which are often washed away and brought to the sea. Next, you can make sure you are using as little electricity at home as possible, causing less of a need for power plants to produce as much as they do. This will result in industries dispelling less CO2 into the atmosphere and contributing less to global warming; driving less and even investing in an eco-friendly car will reduce CO2 emissions, as well. Of course, above all else, educate your friends, family, teachers, and even mortal enemies about the ongoing effects of these impacts.
Humans need the ocean to live. And while many negative things have happened to the ocean, there is still time to act, change, and advocate before it is too late.
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