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  • Writer's pictureKaitlynaMac

Vanishing Reefs

I'm sure that most people have dreamed of being able to either snorkel or scuba in one of the Earth's most colourful and diverse environments. If you haven't dreamed of this yourself, then you probably at least know someone who has, or you've seen one of thousands of advertisements for this very activity multiple times in your life. The sad thing is, this dream is becoming more and more of an impossibility. Due to climate change and pollution, the oceans' coral reefs are disappearing, which is a travesty for more than just your vacation plans. Today we want to talk about the coral reefs: What's happening to them, their importance, and how they can be saved.

Photo courtesy of "Coral Reef Alliance"

Coral reefs like the one featured above are actually quite rare and make up only about 1% of the ocean floor (However, only about 20% of the ocean floor has been explored, so there might be mysterious coral reefs out there! Or deep-sea reefs with glowing coral, who knows!). If we combined all the reefs in the world, the resulting mass would only cover an area about the size of Nevada. Over the past 10 years alone, climate change and pollution have caused the deaths of about 14%, or close to 11,700 square kilometres of coral reefs. The main culprits include acidification, pollution and harmful fishing practices, but global warming is believed to be the worst offender.

Acidification of the ocean is caused by the absorption of carbon dioxide in larger than tolerable amounts. The ocean is one of Earth's greatest 'carbon sinks', and scientists had estimated that the ocean absorbed about 25% of all CO2 created by humans and their activities. However, a recent study suggests that that percentage could actually be a lot higher. CO2 dissolves into the surface of water, which then "sinks" and becomes trapped in those briny depths for hundreds of years before eventually cycling back into the atmosphere. The ocean was originally 'carbon neutral', but since atmospheric CO2 has been increasing steadily since the industrial revolution, it has been absorbing more and more CO2, beyond the limits of its capacity. This trend affects coral by inhibiting their ability to produce their calcium carbonate exoskeletons which protects them from harsh environments and predators.

Pollution is a huge problem the world over, and I'm sure you've heard about that trash island floating around in the Pacific. Though sometimes the biggest aggressors are the ones that we can't see, as opposed to those we can. In the case of corals, the biggest threats in terms of pollution are chemical and sedimentary. Things like agricultural runoff (herbicides and pesticides), oil and gas spills (please see our blog post about the oil industry for more information), untreated sewage discharge and sediment from erosion create a toxic environment that ANYTHING, let alone sensitive corals, would find hard to survive in.

Harmful fishing practices affect more than just fish stocks. I know, when I heard this one I was also a little perplexed at first, but it turns out that some fishers will do anything to maximize their catches. One such practice is 'cyanide fishing', where cyanide is sprayed into the water to stun fish in order to capture them alive. This practice is fueled by foodie culture, where restaurant-goers demand to eat only the freshest of fish; ones that they can see swimming around in dining room tanks. A high-quality live fish fetches a higher price than a dead one, and more fish can be caught more easily with cyanide... so you can guess what happens. Of course, spraying tonnes of poison into water around coral reefs is going to have a deadly effect.

Photo courtesy of "Alaska Tsunami"

Other ways that fishing can harm reefs are through 'blast fishing' and trawling. Blast fishing is exactly what you would expect: Using explosives to stun or kill fish in order to 'scoop' them up more easily. The vibrations and the silt that this inevitably stirs up molests the corals and causes them to wither and die. Trawling, as I'm sure you're aware, involves dragging gear across the ocean floor, kicking up dust and destroying whatever was trying to grow/live there. Terrible. Global warming is one of the symptoms of climate change. As ocean temperatures increase, coral polyps will actually evacuate their symbiotic algae called zooxanthellae, that they depend on for food, and whose chlorophyll create the vibrant pigments that we so love and enjoy, and ocean animals rely on for camouflage. This is responsible for the phenomenon called "coral bleaching". Once all the algae is gone, the corals turn white. And no algae, means no food for the corals, so they eventually die. Coral bleaching is considered to be the number one cause of coral reef deaths amongst all the previously listed issues.

Photo courtesy of ""

Why are Coral reefs important?

Coral reefs are often compared to rainforests, both for their beauty and wealth of biodiversity, not to mention their economic earning potential. Scientists guess that around 4000 fish species depend on the reefs for shelter and food, though this number could be considerably higher. About 25% of the ocean's total marine life rely on reefs at one point or another during their existence. Whether it be to mate, lay eggs or give birth, hunt, scavenge, or escape predators, coral reefs lend to the survival of many other plants and animals. If the reefs disappear, then much of that biodiversity will disappear as well. Humans benefit from coral reefs by using them to reap cold, hard cash. Worldwide, food collection, commercial fishing, and tourism are estimated to generate about $2.7 trillion annually. The reef system in the Florida keys is estimated to provide about $100 million to local fisheries alone. Clearly humans have an economic, as well as moral, incentive to halt the destruction and return the corals' habitats to livable conditions. But at this point, is it possible?

Photo courtesy of "The Travel"

can reefs be saved?

A study on reefs conducted by the Global Coral Reef Monitoring Network observed that 2% of the dead or dying reefs they studied in 2019 were able to bounce back, proving that reefs can be and are hardy and resilient when those harmful factors are removed from their environment. Most experts agree that the only way to absolutely solve this issue and save the corals is to stop, and hopefully reverse, climate change. Corals evolved into existence about 400 million years ago and have survived many changes in temperature and climate over the eons since, but never have they had to adapt as quickly as they have had to do during the last few decades. Through the fossil record, scientists know that there have been at least 6 coral mass extinctions in the past, though once gone, it will take tens of thousands of years for them to return, provided that the amount of CO2 which caused the extinction has abated. Another interesting solution is being explored in the Florida Keys. One research center is selectively breeding corals that are resilient to rising temperatures. Erinn Muller, the science director at the Elizabeth Moore International Center for Coral Reef research and Restoration, and her team collect specimens that seem to be surviving well in the warmer waters and then breed them by hand. Later, when the corals are mature, the scientists reattach them to the reef. On average the center has around 46,000 corals growing in its laboratory. They have grown over 70,000 corals from five different species to date. Other scientists are studying so-called "super reefs" that grow in naturally warmer waters. Their goals are to identify the specific genes responsible for heat resilience and hopefully use that information to bolster reefs and to figure out if there is a "cap" to corals' adaptability.

However, even with all of these promising endeavors yielding positive results, ultimately the best way to save all of the reefs is to reduce emissions, runoff, pollution, etc. And return the oceans to a state where every creature can flourish.

Photo courtesy of "Science"


Gibbens, Sarah. “The World’s Coral Reefs Are Dying—Here’s How Scientists Plan to Save Them.” Science, National Geographic, 4 June 2020,

“How Much Carbon Does the Ocean Absorb? | World Economic Forum.” World Economic Forum,,world’s%20largest%20’carbon%20sinks’. Accessed 13 Feb. 2022.

Ross, Rachel. “What Are Coral Reefs? | Live Science.” Livescience.Com, Live Science, 24 Sept. 2018,

“Scientists Pinpoint How Ocean Acidification Weakens Coral Reefs.” Woods Hole Oceanographic Institution,,-Topics%3A%20Coral%20%2F%20Ocean&text=The%20rising%20acidity%20of%20the,corals%20to%20build%20their%20skeletons.&text=Corals%20grow%20their%20skeletons%20upward,thicken%20them%20to%20reinforce%20them. Accessed 13 Feb. 2022.

Welle, Deutsche. “Climate Change Killed 14% of the World′s Coral Reefs in 10 Years: Study | News | DW | 05.10.2021.” DW.COM, Deutsche Welle (,

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