Coral reefs, often called the “rainforests of the sea,” are among the most diverse and vital ecosystems on Earth. Made up of tiny organisms known as polyps, these reefs provide food, shelter, and breeding grounds for about 25% of marine life, playing a crucial role in maintaining ocean biodiversity. However, coral reefs worldwide are facing unprecedented threats and are dying at alarming rates.
Climate change, rising sea temperatures, ocean acidification, pollution, and overfishing are just a few of the factors driving coral reef degradation. Without immediate action, many coral reefs could vanish within the next few decades, leading to devastating consequences for marine ecosystems and human communities alike. Explore why coral reefs are dying and which types of reefs are on the brink of extinction.
What are coral reefs?
Coral reefs are underwater ecosystems, often referred to as the “rainforests of the sea,” because they support an extraordinary variety of marine life. These ecosystems are made up of tiny organisms called polyps that secrete calcium carbonate, creating the hard structures we recognize as coral.
They provide shelter and food for about 25% of all marine species, making them critical to marine biodiversity. However, coral reefs are in grave danger, with many facing a growing risk of extinction.
Why are coral reefs dying?
The degradation of coral reefs is happening at an alarming rate due to several factors, both natural and human-made. Some of the leading causes include:
Climate change
Rising sea temperatures are one of the biggest threats to coral reefs. Corals are highly sensitive to temperature changes, and when water becomes too warm, they expel the symbiotic algae living in their tissues (zooxanthellae). This process is known as coral bleaching. Without these algae, corals lose their primary source of food and their vibrant colours, eventually leading to their death.
Ocean acidification
The ocean absorbs about 30% of the CO2 in the atmosphere, and as CO2 levels increase due to human activities, the ocean becomes more acidic. This acidification makes it harder for corals to build their calcium carbonate skeletons, weakening them and reducing their resilience to environmental changes.
Pollution
Runoff from agricultural lands, untreated sewage, and plastic pollution damage coral reefs. Chemicals such as pesticides and fertilisers contribute to nutrient overloads, which promote harmful algal blooms. These blooms can block sunlight that corals need to thrive, while plastic waste physically damages coral structures.
Overfishing and destructive fishing practices
Practices such as dynamite fishing and the use of cyanide poison for fishing have a devastating impact on coral reefs. Overfishing also disrupts the balance of the marine ecosystem, leading to coral degradation.
Coastal development
The construction of resorts, ports, and other coastal infrastructure can directly damage reefs through physical destruction, increased sedimentation, and habitat loss.
Coral reefs on the brink of extinction
Some coral reefs are particularly vulnerable and may face extinction within a few decades if current trends continue. Here are some types of coral reefs that are on the verge of death:
Great Barrier reef (Australia)
The largest coral reef system in the world, the Great Barrier Reef has experienced significant coral bleaching events in recent years, driven primarily by warming sea temperatures. Between 2016 and 2017, about 50% of its coral cover was lost. This reef is one of the most iconic examples of the impacts of climate change on coral ecosystems.
Chagos Archipelago (Indian Ocean)
Once home to some of the healthiest coral reefs, this region has seen severe bleaching events, especially during the El Niño events. The Chagos reefs have suffered a reduction in coral cover and biodiversity.
Caribbean reefs
Coral reefs in the Caribbean have been hit hard by climate change, pollution, and overfishing. The Caribbean has lost more than half of its coral population in the last 30 years. Reefs in countries like Jamaica and the Bahamas have experienced severe degradation.
Southeast Asia’s coral triangle
Known as the global centre of marine biodiversity, the Coral Triangle covers the waters of Indonesia, Malaysia, the Philippines, Papua New Guinea, and other neighbouring areas. While it is home to some of the most diverse coral reefs, overfishing, destructive fishing practices, and coastal development have pushed many reefs in this region to the brink of collapse.
Florida Keys (United States)
Coral reefs in the Florida Keys have seen a drastic decline, with about 90% of the coral cover lost over the last 50 years. Climate change, pollution, and boating activities have all contributed to this severe loss, putting the remaining corals at significant risk.
Coral reefs of the Virgin Islands (United States)
The reefs around the U.S. Virgin Islands have experienced significant bleaching and disease outbreaks due to rising ocean temperatures and pollution.
Apo reef (Philippines)
The second-largest contiguous coral reef in the world, Apo reef faces the threats of coral bleaching, overfishing, and destructive fishing practices. It is one of the most biologically diverse but vulnerable reefs in Southeast Asia.
Yabiji (Japan)
Located in the Ryukyu Islands, Yabiji is the largest coral reef in Japan and has suffered significant bleaching events in recent years due to rising sea temperatures. Coral cover has been greatly reduced, placing it at risk.
Also read: 10 weird-looking birds in the world you might have never heard of
