As more and more climate change impacts are being witnessed – from hurricanes increasing in frequency and intensity to ice caps melting over Greenland – the world is beginning to pay more attention to climate change and realize the severity of the situation. Not only are individual species disappearing in the wild and sea levels slowly rising, but scientists have come to the realization that entire ecosystems can be lost.
This is becoming the unfortunate reality for one of the most magical underwater habitats: coral reefs. Although reefs are threatened by overfishing and sediment runoff, negative impacts on reefs are exacerbated by rising water temperatures due to climate change.
What Are Coral Reefs?
Coral reefs are ocean habitats occurring in shallow tropical waters. They contain the highest biodiversity on earth, despite only covering 0.1% of the ocean. An estimated one million species of fish, invertebrates, corals and algae can be found on or near coral reefs, and these are only the species that have been documented.
Coral reefs consist of a symbiotic relationship between photosynthetic algae and thousands of individual coral polyps, which are animals. These polyps are immobile, and depend on the algae to provide food and energy.
Why Are Corals Important To Humans?
Not only do corals provide habitat and food to a myriad of marine organisms, they are also crucially important to humans as well. In smaller tropical countries, fish are an important subsistence resource to local communities, but are also economically important through the sale of fish. These same nations often depend heavily on tourism for foreign currency, and healthy reefs are a huge driver of tourism.
Coral reefs also act as barriers to shorelines, and protect the coast from high wave energy that can erode beaches. Eroding beaches can cause expensive structural damage, as well as pose a safety risk to people. As climate change is increasing, the frequency and intensity of storm surges in tropical waters, reef protection of shorelines will become increasingly important.
The Coral Reefs Are Dying
Global warming is one of the greatest threats to coral reefs. As the ocean’s temperature rises, the corals undergo stress that results in what is known as “coral bleaching”. Bleaching occurs when sea temperatures are abnormally warm, and corals expel their symbiotic algae that provide them with their bright colors, leaving a clear polyp on a white calcium carbonate skeleton. A bleached coral is still alive and has the ability to recover, but when bleaching occurs for long periods of time, the corals die.
Time is running out for coral reefs all over the world. Since we depend on the oceans, the bad news for reefs is indeed bad news for the rest of the ocean and for humanity. According to a new report published in the journal Nature, one-third of the 3,863 reefs that make up the Great Barrier Reef — the world’s biggest and most complex reef system — died as a result of a severe heat wave in 2016. A bleaching outbreak in 2017 wreaked even more havoc on the coral, with the accumulated effects killing half of the magnificent system in just two years.
The same devastation is hitting reefs around the world. According to some estimates, similar conditions around the globe have killed off about half the world’s coral reefs in the past 30 years.
A Hypothetical World Without Coral Reefs
Less Fish in the Ocean
Coral reefs are known as “the rainforests of the sea” and provide a quarter of marine species with habitat and food. If coral reefs disappeared, essential food, shelter and spawning grounds for fish and other marine organisms would cease to exist, and biodiversity would greatly suffer as a consequence. Marine food-webs would be altered, and many economically important species would disappear.
Collapsing Fishing Industry
This will have a domino effect, as fishing industries would be adversely affected. According to the United Nations, approximately one billion people depend on coral reefs for their food and livelihoods. The absence of corals would have a catastrophic effect on hundreds of millions of people around the world, who would lose their main source of food and income. The shortage of seafood in diets would also result in more pressure on land-based farming and aquaculture industries to make up for this shortage.
No More Tourists
Coral reefs also sustain smaller economies through tourism, and attract tourists to over 00 countries. Without reefs to visit, there will be a decline in tourist numbers, which will have a knock-on effect on local businesses who depend on year-round tourists. Restaurants, hoteliers, street vendors and tour guides would all be affected.
Losing Our Coastlines
The most significant impact that would occur if coral reefs were to disappear, is the negative impact on coastlines. Shorelines will become battered by waves and extreme weather events, and become vulnerable to erosion. Erosion of the coast, combined with sea-level rise due to climate change, will push coastal communities from their homes and further inland.
Loss of Medical Research
A less well-known impact should we lose our leave is the impact on medical breakthroughs. The organisms that live within reefs provide new treatments for human diseases and ailments. By studying corals’ natural chemical defenses to predators, researchers were able to develop medicines to treat all sorts of diseases – including cancer, arthritis, Alzheimer’s, and heart disease.
Algae and Jellyfish
Some scientists have also suggested that the seafloor might become dominated by algae. As skeletal structures of limestone reefs break away, microbial life would absorb energy from the sun, producing algae. The algae will in turn attract jellyfish, who graze on the algae and microbes.
Way Less Oxygen
Approximately 50-80% of our oxygen is produced in our oceans by plankton and photosynthesizing bacteria. This oxygen is not only absorbed by marine life, but also by humans as it is expelled into the atmosphere. Coral reefs are needed for a healthy ocean, and a healthy ocean is thus needed for a healthy atmosphere.
Hope For The Future
Although the hypothetical scenario described above is becoming a real possibility due to the ongoing loss of coral reefs across the world’s oceans, all hope is not lost yet. Researchers are looking at proactively protecting corals. Corals are being grown in nurseries to repopulate damaged reefs. In the protected environment of a nursery, corals are able to grow much faster than in a high-stress ocean environment. On land there is also a big movement towards sustainable living, recycling, and consuming less fossil fuels. Corals are able to bounce back from coral bleaching, so there is hope that they will be able to bounce back from the current global situation.