Why are coral reefs dying
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Why are Coral Reefs Dying? And Actions To help Save the Reefs

Coral reefs, one of the most diverse and valuable ecosystems on Earth, are facing unprecedented challenges and are dying at an alarming rate. In addition to being incredible underwater riches, coral reefs are also crucial to the health of our world. We must strive to preserve and conserve these invaluable ecosystems, as the destruction of coral reefs has far-reaching ecological and economic consequences.

The primary reasons for their decline are rising ocean temperatures caused by climate change, ocean acidification, pollution, overfishing, and disease. 

The changing climate is causing coral bleaching, in which corals lose their vibrant colors and struggle to survive.

Ocean acidification, resulting from the absorption of carbon dioxide in the ocean, makes it difficult for corals to develop and maintain their skeletons. Human activities, such as pollution from fertilizers and sewage, overfishing, and coastal development, further affect the delicate coral reef ecosystems.

What are Coral Reefs?

Coral reef landscape
Photo by Oleksandr Sushko on Unsplash

The United States Environmental Protection Agency (EPA) describes the coral reef ecosystem as an intricate and diverse collection of species interacting with each other and the physical environment. 

Coral is a class of colonial animals related to hydroids, jellyfish, and sea anemones. The many different types of coral are found in deep and shallow waters and are renowned for the variety of species they support and their vivid hues9.

Coral reefs comprise thin layers of calcium carbonate, a substance that coral polyps produce. The polyps develop a structure that serves as the framework for the entire reef ecosystem as they expand and multiply. 

New polyps eventually settle on the reef and aid in its expansion, fostering the development of a complex and diverse community of species that co-exist peacefully. 

NOAA reported that massive corals develop slowly, expanding between 0.2 and 0.8 inches (0.5 to 2 cm) annually. However, in optimal circumstances, some species can develop as much as 4.5 cm (1.8 inches) every year (plenty of light, constant temperature, moderate wave activity).

The Importance of Coral Reefs

Coral reefs are vital to the health and balance of the marine ecosystem. They are the largest structures made by living organisms and provide habitat and food for a diverse array of marine life, making them one of the most biologically diverse ecosystems on the planet.

Reef structures serve as a foundation for an incredibly diverse range of species, providing food, shelter, and breeding grounds for various fish, mollusks, crustaceans, and other animals.

According to the National Oceanic and Atmospheric Administration, coral formations support more species per unit area than any other marine environment, including about 4,000 species of fish, 800 species of hard corals, and hundreds of other species.

Coral reefs also play a crucial role in maintaining the stability of the ocean's ecosystem by providing a physical structure that helps to shape the local environment and regulate the flow of nutrients and other materials2. Some of the major benefits of coral reefs include:

1. Coastal Protection

Coral reefs buffer shorelines and serve as a natural defense against storms and waves, lessening their effects on neighboring coastal areas. This can enhance coastal communities' general stability and help minimize erosion and flood hazards. 

Coral formations, for instance, can significantly lessen coastal flooding and erosion by dispersing as much as ninety-seven percent (97%) of incident wave energy, according to the United States Geological Survey.

The mechanism operates because the coral reefs absorb the energy of approaching waves and disperse it over a vast area, weakening the waves before they reach the coast. This is crucial in regions susceptible to extreme weather conditions, like hurricanes, typhoons, and tsunamis. 

Coral reefs not only directly protect coastal communities but also work to safeguard other crucial coastal habitats like mangrove swamps and seagrass beds, which benefit the environment by improving water quality and increasing fish and wildlife populations.

Over time, the effects of coastal construction and polluted runoff from coastal areas can harm coral reefs. To conserve delicate coral ecosystems and the organisms that live there, sustainable coastal development methods are necessary for maintaining coral reef health3.

2. Economic Benefits

Coral reefs provide economic benefits to several sectors, including tourism, fishing, pharmaceuticals, education, and research. Coral reefs are major tourist attractions, attracting millions of visitors each year who enjoy the beauty and biodiversity of these unique ecosystems. Tourism is the primary source of income for local communities in many areas, and reef structures are often a major draw for visitors. 

In a report by Mapping Ocean Wealth, models discovered that coral reefs sustain approximately 70 million journeys annually and are worth $36 billion to the global economy, making them a significant driving force behind coastal and marine tourism.

Related: 15 Best Tips For Eco-Friendly Travel & Sustainable Adventures 

Coral formations support profitable fisheries by offering habitat and food to several significant species, including lobster, shrimp, and tuna. For local communities in many places, fishing is a vital source of food and revenue, and coral reefs are crucial to the health of these sectors. 

According to NOAA, coral reefs enrich the United States economy with more than 3.4 billion dollars4. The marine fisheries services estimated the annual commercial value of U.S. fisheries from reef structures to be over $100 million annually from recreational fisheries.

3. Medical Applications

Natural substances with potential uses in the pharmaceutical and medical fields are abundant in coral reef ecosystems6. Numerous of these substances have already been turned into medicines used to treat some ailments, such as cancer, arthritis, and heart disease. 

According to projections, ecosystems will be a major source of pharmaceuticals, dietary supplements, insecticides, cosmetics, and other commercial goods.

Why are Coral Reefs Dying?

Dead bleached coral
Bleached coral photographed in the Gulf of Thailand. Photo Credit: Eco Cafe' Pranburi (CC BY-SA 2.0)

Although reef structures only make up 0.2% of the ocean floor, they are found in more than 100 countries and territories. They are essential to the survival of at least 25% of marine species and the safety, protection of coastlines, health, and economic security of hundreds of millions of people.

Amidst all these economic and ecological benefits, it is sad to have coral reefs dying due to numerous global and local threats due to human activities such as pollution, overfishing, declining water quality, climate change, and unsustainable coastal construction. 

"Why are coral reefs dying?" is a valid question, as measures to protect coral reef health in the world's oceans and prevent further deterioration of reef structures are more important than ever. The factors that disrupt the delicate balance of the coral formation ecosystem, causing the decline and death of coral species, include:

1. Climate Change

Coral reef health can be negatively impacted by climate change in a variety of ways, such as: 

  1. Coral Bleaching: As ocean temperatures rise, coral expels the symbiotic algae that coexist with them in their tissues. Coral bleaching events cause the coral to lose color and nutrients. Eventually, the coral reefs die, turning white in the process, hence the name, bleaching.
  2. Increasing Ocean Temperatures and Sea Level Changes: Rising sea temperatures, decreased sea level, and increased salinity from altered rainfall can all result from el niño weather patterns. Together these conditions can have devastating effects on a coral’s ecology. High water temperatures can cause coral to expel the symbiotic algae that provide nourishment and vibrant color for their hosts5. This coral bleaching can cause the coral to die, while rising sea levels exacerbate storms and erosive processes. Changes in ocean currents can also alter the availability of nutrients and have an impact on coral growth and survival.
  3. Change in Ocean Chemistry: The world's oceans are becoming increasingly acidic due to the surplus carbon dioxide in the atmosphere. As a result, coral's development rate slows down, and structural issues such as their inability to build a skeleton may result in increased coral breaks7

2. Overfishing

Overfishing is collecting more fish than the ocean can sustainably produce. This practice often involves destructive fishing methods resulting in the decline of important species and the instability of the coral reef ecosystem. 

The loss of reef biodiversity can have various consequences that worsen the coral's condition, eventually leading to its death. Overfishing disrupts the balance of the coral reef ecosystem in several ways.

  1. Disruption of the food chain: It can result from overfishing of predators like groupers and snapper, which can lead to an increase in parasites and herbivores that eat coral and further harm the reef.
  2. Removing key species: Overfishing of herbivores, such as parrotfish, disrupts the balance of the ecosystem by removing important species that keep coral free of algae. This allows the algae to overgrow and smother the coral, leading to its death.
  3. Destabilizing the ecosystem: Overfishing large predatory fish can increase the crown of thorns starfish that feed in coral polyps, destabilizing the ecology by lowering the number of recruits for the reef community.
  4. Increasing sedimentation: Overfishing of species like sea urchins and conchs, which aid in controlling sedimentation, can result in more sediment and less clear water, further harming the reef.
  5. New species introduction: Overfishing can leave ecological gaps that invite the establishment of invasive species that compete with native species for resources, further weakening the ecosystem of coral formations.

3. Pollution

Diver clearing plastic waste from coral reef
Photo: iStock

When coral structures are choked, harmful algae are allowed to develop more quickly, and the water quality is decreased when silt and other pollutants enter the water. In addition to impeding coral growth and reproduction and changing the food structures on the reef, pollution can render corals more vulnerable to diseases8.

When chemicals and pollutants from human activities, such as agriculture and industry, find their way into the ocean, they can alter the delicate balance of marine ecosystems.

Pollution is a significant contributor to the death of coral reefs. Chemical pollution can create toxic conditions that harm the coral, plastic pollution can entangle and suffocate the coral, and sediment pollution can reduce the amount of light that reaches the reef, inhibiting its ability to photosynthesize and survive.

In addition, rising water temperatures can cause coral reefs to bleach, a process where the coral expels the symbiotic algae within its tissues, leaving it vulnerable to disease and death.

4. Natural disasters

Natural disasters can cause significant harm to coral structures, and if these events occur frequently, they can push the reef ecosystem to the brink of collapse. Strong storms that cause physical damage to the reef structures and uproot or destroy the coral colonies include hurricanes and typhoons. This devastates the reef's internal structure and can lead to species loss and alter the ecosystem's delicate balance.

Coral reefs can also be significantly impacted by tsunamis, large ocean waves brought on by earthquakes, or volcanic eruptions. The sheer power of the water has the potential to physically destroy large portions of the reef while also causing a deposit of sediment that can suffocate and kill the coral.

Additionally, variations in water temperature, salinity, and nutrient concentrations brought on by natural disasters may have a long-term impact on the reef's health.

Coral reefs also die from diseases, physical damage, and invasive species. Diseases spread swiftly within coral colonies, resulting in widespread demise and a decline in the reef's general health.

Coral can suffer physical harm from human activities like fishing, boating, and diving. Invasive species can also outcompete native species in resource competitions, disrupt the delicate ecosystem's balance, and damage the reef's overall health.

Knowing the threats to coral reef health and marine life, mitigating these impacts, and saving coral formations for future generations is important.

5. Sunscreen

Sunscreen, which many people use to protect against harmful ultraviolet radiation, has recently emerged as a silent threat to the delicate ecosystems of coral reefs. 

Specific sunscreen components, oxybenzone, and octinoxate, harm coral reefs and marine life. When beachgoers wearing sunscreen swim in the ocean, these chemicals seep into the water and accumulate in harmful concentrations.

Research shows that oxybenzone and octinoxate stunt coral growth1, intensify coral bleaching, and cause genetic damage that weakens coral reproduction ability and survival. 

Read more: Environmental impact of sunscreen

How can we save coral reefs?

Coral reef and fish
Photo by Francesco Ungaro on Unsplash

Saving coral reefs is a critical challenge that requires a multi-faceted approach. Here are some of the key steps that can be taken to protect and conserve the world’s coral reefs:

  • Reduce pollution: Reducing the amount of pollutants that enter the ocean is one of the most important steps we can take to save coral reefs. This can be achieved by reducing plastic waste, improving wastewater treatment, and adopting better agricultural practices.
  • Prevent overfishing:  We can contribute to ensuring the long-term health of coral reefs by applying sustainable fishing techniques and safeguarding key regions through marine protected zones.
  • Manage coastal development: Increased sedimentation, nutrient pollution, and physical harm are just a few of the negative impacts that shoreline construction can have on coral formations. We can lessen the damage done to coral reefs by regulating development and implementing best practices for coastal construction into place.
  • Reduce the consequences of climate change: Due to rising ocean temperatures and increased ocean acidification, coral reefs are at serious risk from climate change, which can lead to coral bleaching and eventual death. It's essential to reduce greenhouse gas emissions contributing to global warming and work toward a more sustainable future to mitigate these effects.
  • Reef restoration: In regions where coral reefs have been harmed, restoration efforts can be performed using strategies like coral transplantation, improving natural recovery processes, and managing invasive species.
  • Public awareness:  Teaching people about the value of coral reefs and the dangers they face is a crucial first step in ensuring their survival. This can be accomplished through public involvement, outreach initiatives, and advocacy campaigns.
  • Opt for reef-safe sunscreen: A growing awareness of sunscreen's impact on coral reefs has prompted efforts to promote coral-safe sunscreen alternatives and ban harmful chemicals in tourist hotspots. Our selection of zero-waste sunscreens includes many reef-safe versions that also help to minimize waste. Check the label of your sun protection and choose those without chemicals likely to cause harm to corals. 

To ensure the survival of coral reefs and the rich diversity of species that depend on them, we must take action to reduce the threats they face and implement effective conservation and management strategies. By adopting these actions, we can protect coral reefs and ensure that these important ecosystems will continue to support a diverse range of marine wildlife in future years. 


In conclusion, the decline of coral reefs is a global issue that requires immediate attention. One of the ocean's most valuable resources is its coral reefs. These critically important and biologically varied organisms may be severely damaged without individual and societal action. 

The loss of these valuable ecosystems will have far-reaching consequences, including declining biodiversity, losing shoreline protection, and economic hardship for coastal communities. To ensure coral reef conservation, we must take immediate action to reduce pollutants, implement sustainable fishing practices, and mitigate the effects of global warming and climate change.


Downs, C. A., Kramarsky-Winter, E., Segal, R., Fauth, J., Knutson, S., Bronstein, O., Ciner, F. R., Jeger, R., Lichtenfeld, Y., Woodley, C. M., Pennington, P., Cadenas, K., Kushmaro, A., & Loya, Y. (2016). Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands. Archives of environmental contamination and toxicology70(2), 265–288.


Komyakova, V., Munday, P. L., & Jones, G. P. (2013). Relative Importance of Coral Cover, Habitat Complexity and Diversity in Determining the Structure of Reef Fish Communities. PLOS ONE, 8(12), e83178.


Nanajkar, M., De, K., & Ingole, B. (2019). Coral reef restoration-a way forward to offset the coastal development impacts on Indian coral reefsMarine Pollution Bulletin149, 110504.


Brander, L., & Beukering, P. V. (2013). The total economic value of US coral reefs: a review of the literature (pdf) NOAA.


Riegl, B., Bruckner, A., Coles, S. L., Renaud, P., & Dodge, R. E. (2009). Coral reefs: threats and conservation in an era of global change. Annals of the New York Academy of Sciences, 1162(1), 136-186.


Cooper, E. L., Hirabayashi, K., Strychar, K. B., & Sammarco, P. W. (2014). Corals and their potential applications to integrative medicine. Evidence-based complementary and alternative medicine, 2014.


Hoegh-Guldberg, O., Mumby, P. J., Hooten, A. J., Steneck, R. S., Greenfield, P., Gomez, E., ... & Hatziolos, M. (2007). Coral reefs under rapid climate change and ocean acidificationscience318(5857), 1737-1742.


Dubinsky, Z. V. Y., & Stambler, N. (1996). Marine pollution and coral reefsGlobal change biology2(6), 511-526.


Sheppard, C., Davy, S., Pilling, G., & Graham, N. (2017). The biology of coral reefs. Oxford University Press.

By Jennifer Okafor, BSc.

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

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